diff --git a/creusot/tests/should_succeed/100doors/why3session.xml b/creusot/tests/should_succeed/100doors/why3session.xml
index 6688971c2..60fe04907 100644
--- a/creusot/tests/should_succeed/100doors/why3session.xml
+++ b/creusot/tests/should_succeed/100doors/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="100doors.mlcfg"/>
 <theory name="C100doors_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.327048" steps="945633"/></proof>
+ <proof prover="0"><result status="valid" time="0.122415" steps="658174"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/100doors/why3shapes.gz b/creusot/tests/should_succeed/100doors/why3shapes.gz
index 1b88a2a40..ba4a74b36 100644
Binary files a/creusot/tests/should_succeed/100doors/why3shapes.gz and b/creusot/tests/should_succeed/100doors/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/all_zero/why3session.xml b/creusot/tests/should_succeed/all_zero/why3session.xml
index d2ba41cbc..d01bdef72 100644
--- a/creusot/tests/should_succeed/all_zero/why3session.xml
+++ b/creusot/tests/should_succeed/all_zero/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="all_zero.mlcfg"/>
 <theory name="AllZero_AllZero" proved="true">
  <goal name="all_zero&#39;vc" expl="VC for all_zero" proved="true">
- <proof prover="1"><result status="valid" time="0.038573" steps="808"/></proof>
+ <proof prover="0"><result status="valid" time="0.038573" steps="806"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bdd/why3session.xml b/creusot/tests/should_succeed/bdd/why3session.xml
index 73f9d9820..a3650a77f 100644
--- a/creusot/tests/should_succeed/bdd/why3session.xml
+++ b/creusot/tests/should_succeed/bdd/why3session.xml
@@ -2,9 +2,7 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="CVC4" version="1.8" timelimit="5" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.5.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="4" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="6" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
@@ -17,7 +15,7 @@
 </theory>
 <theory name="Bdd_Impl7_Eq" proved="true">
  <goal name="eq&#39;vc" expl="VC for eq" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="808"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.003136" steps="539"/></proof>
  </goal>
 </theory>
 <theory name="Bdd_Impl14_Eq" proved="true">
@@ -27,7 +25,7 @@
 </theory>
 <theory name="Bdd_Impl0_Clone" proved="true">
  <goal name="clone&#39;&#39;vc" expl="VC for clone&#39;" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="641"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.002978" steps="427"/></proof>
  </goal>
 </theory>
 <theory name="Bdd_Impl15_Clone" proved="true">
@@ -42,12 +40,12 @@
 </theory>
 <theory name="Bdd_Impl2_Hash" proved="true">
  <goal name="hash&#39;vc" expl="VC for hash" proved="true">
- <proof prover="0"><result status="valid" time="0.020000" steps="761"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.003323" steps="513"/></proof>
  </goal>
 </theory>
 <theory name="Bdd_Impl8_Size_Impl" proved="true">
  <goal name="size&#39;vc" expl="VC for size" proved="true">
- <proof prover="0"><result status="valid" time="0.020000" steps="1203"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.005392" steps="905"/></proof>
  </goal>
 </theory>
 <theory name="Bdd_Impl10_GrowsIsValidBdd_Impl" proved="true">
@@ -537,7 +535,7 @@
   <proof prover="6"><result status="valid" time="0.085307" steps="5854"/></proof>
   </goal>
   <goal name="and&#39;vc.29" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.067880" steps="258665"/></proof>
+  <proof prover="4"><result status="valid" time="0.067819" steps="251609"/></proof>
   </goal>
   <goal name="and&#39;vc.30" expl="precondition" proved="true">
   <proof prover="6"><result status="valid" time="0.091440" steps="8389"/></proof>
@@ -551,13 +549,13 @@
      <goal name="and&#39;vc.31.0.0.0" expl="precondition" proved="true">
      <transf name="split_vc" proved="true" >
       <goal name="and&#39;vc.31.0.0.0.0" expl="precondition" proved="true">
-      <proof prover="2"><result status="valid" time="0.084472" steps="395875"/></proof>
+      <proof prover="4"><result status="valid" time="0.112833" steps="544049"/></proof>
       </goal>
       <goal name="and&#39;vc.31.0.0.0.1" expl="precondition" proved="true">
-      <proof prover="2"><result status="valid" time="0.209960" steps="532284"/></proof>
+      <proof prover="4"><result status="valid" time="0.050164" steps="216783"/></proof>
       </goal>
       <goal name="and&#39;vc.31.0.0.0.2" expl="precondition" proved="true">
-      <proof prover="2"><result status="valid" time="0.104813" steps="458944"/></proof>
+      <proof prover="4"><result status="valid" time="0.101796" steps="451427"/></proof>
       </goal>
      </transf>
      </goal>
@@ -575,10 +573,10 @@
       <proof prover="6"><result status="valid" time="0.252434" steps="42233"/></proof>
       </goal>
       <goal name="and&#39;vc.31.1.0.0.1" expl="precondition" proved="true">
-      <proof prover="2"><result status="valid" time="0.086875" steps="396721"/></proof>
+      <proof prover="4"><result status="valid" time="0.064557" steps="280230"/></proof>
       </goal>
       <goal name="and&#39;vc.31.1.0.0.2" expl="precondition" proved="true">
-      <proof prover="2"><result status="valid" time="0.120648" steps="541351"/></proof>
+      <proof prover="4"><result status="valid" time="0.109090" steps="462414"/></proof>
       </goal>
      </transf>
      </goal>
@@ -589,7 +587,7 @@
   </transf>
   </goal>
   <goal name="and&#39;vc.32" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.116839" steps="146074"/></proof>
+  <proof prover="4"><result status="valid" time="0.034477" steps="140173"/></proof>
   </goal>
   <goal name="and&#39;vc.33" expl="precondition" proved="true">
   <proof prover="3"><result status="valid" time="0.029470" steps="43"/></proof>
@@ -666,10 +664,10 @@
   </transf>
   </goal>
   <goal name="and&#39;vc.37" expl="postcondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.148957" steps="549303"/></proof>
+  <proof prover="4"><result status="valid" time="0.160674" steps="533439"/></proof>
   </goal>
   <goal name="and&#39;vc.38" expl="postcondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.211103" steps="1215556"/></proof>
+  <proof prover="4"><result status="valid" time="0.073766" steps="268860"/></proof>
   </goal>
   <goal name="and&#39;vc.39" expl="postcondition" proved="true">
   <transf name="split_vc" proved="true" >
@@ -681,10 +679,10 @@
     <goal name="and&#39;vc.39.0.1" expl="postcondition" proved="true">
     <transf name="split_vc" proved="true" >
      <goal name="and&#39;vc.39.0.1.0" expl="postcondition" proved="true">
-     <proof prover="2"><result status="valid" time="0.041714" steps="199045"/></proof>
+     <proof prover="4"><result status="valid" time="0.045110" steps="188866"/></proof>
      </goal>
      <goal name="and&#39;vc.39.0.1.1" expl="postcondition" proved="true">
-     <proof prover="2"><result status="valid" time="0.192811" steps="822121"/></proof>
+     <proof prover="4"><result status="valid" time="0.127787" steps="511952"/></proof>
      </goal>
      <goal name="and&#39;vc.39.0.1.2" expl="postcondition" proved="true">
      <proof prover="3"><result status="valid" time="0.057312" steps="80"/></proof>
@@ -696,7 +694,7 @@
    <goal name="and&#39;vc.39.1" expl="postcondition" proved="true">
    <transf name="split_vc" proved="true" >
     <goal name="and&#39;vc.39.1.0" expl="postcondition" proved="true">
-    <proof prover="2"><result status="valid" time="0.034327" steps="178213"/></proof>
+    <proof prover="4"><result status="valid" time="0.062736" steps="265170"/></proof>
     </goal>
     <goal name="and&#39;vc.39.1.1" expl="postcondition" proved="true">
     <transf name="split_vc" proved="true" >
@@ -704,7 +702,7 @@
      <proof prover="6"><result status="valid" time="0.088131" steps="12579"/></proof>
      </goal>
      <goal name="and&#39;vc.39.1.1.1" expl="postcondition" proved="true">
-     <proof prover="2"><result status="valid" time="0.206378" steps="406000"/></proof>
+     <proof prover="4"><result status="valid" time="0.094909" steps="398138"/></proof>
      </goal>
      <goal name="and&#39;vc.39.1.1.2" expl="postcondition" proved="true">
      <proof prover="3"><result status="valid" time="0.052401" steps="80"/></proof>
@@ -716,7 +714,7 @@
    <goal name="and&#39;vc.39.2" expl="postcondition" proved="true">
    <transf name="split_vc" proved="true" >
     <goal name="and&#39;vc.39.2.0" expl="postcondition" proved="true">
-    <proof prover="2"><result status="valid" time="0.058120" steps="263688"/></proof>
+    <proof prover="4"><result status="valid" time="0.063540" steps="273966"/></proof>
     </goal>
     <goal name="and&#39;vc.39.2.1" expl="postcondition" proved="true">
     <transf name="split_vc" proved="true" >
@@ -742,7 +740,7 @@
   <goal name="and&#39;vc.40" expl="postcondition" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="and&#39;vc.40.0" expl="postcondition" proved="true">
-   <proof prover="2"><result status="valid" time="0.050306" steps="231721"/></proof>
+   <proof prover="4"><result status="valid" time="0.103712" steps="424427"/></proof>
    </goal>
    <goal name="and&#39;vc.40.1" expl="postcondition" proved="true">
    <proof prover="6"><result status="valid" time="0.119851" steps="30502"/></proof>
@@ -754,22 +752,22 @@
 </theory>
 <theory name="Bdd_Hashmap_Impl2" proved="true">
  <goal name="hash_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="747"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.003279" steps="461"/></proof>
  </goal>
 </theory>
 <theory name="Bdd_Impl1" proved="true">
  <goal name="hash_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="2366"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.008572" steps="1734"/></proof>
  </goal>
 </theory>
 <theory name="Bdd_Impl2" proved="true">
  <goal name="hash_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="662"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.003589" steps="439"/></proof>
  </goal>
 </theory>
 <theory name="Bdd_Impl13" proved="true">
  <goal name="assert_receiver_is_total_eq_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="20"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.002133" steps="27"/></proof>
  </goal>
 </theory>
 <theory name="Bdd_Impl19" proved="true">
@@ -779,12 +777,12 @@
 </theory>
 <theory name="Bdd_Impl14" proved="true">
  <goal name="eq_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="661"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.003799" steps="437"/></proof>
  </goal>
 </theory>
 <theory name="Bdd_Impl7" proved="true">
  <goal name="eq_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="662"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.003839" steps="439"/></proof>
  </goal>
 </theory>
 <theory name="Bdd_Impl15" proved="true">
@@ -794,7 +792,7 @@
 </theory>
 <theory name="Bdd_Impl0" proved="true">
  <goal name="clone&#39;_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="912"/></proof>
+ <proof prover="6" timelimit="5"><result status="valid" time="0.005105" steps="679"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/binary_search/why3session.xml b/creusot/tests/should_succeed/binary_search/why3session.xml
index a8a0859d3..7ab8b6421 100644
--- a/creusot/tests/should_succeed/binary_search/why3session.xml
+++ b/creusot/tests/should_succeed/binary_search/why3session.xml
@@ -2,95 +2,95 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="binary_search.mlcfg"/>
 <theory name="BinarySearch_Impl0_LenLogic_Impl" proved="true">
  <goal name="len_logic&#39;vc" expl="VC for len_logic" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="27"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="27"/></proof>
  </goal>
 </theory>
 <theory name="BinarySearch_Impl0_Index" proved="true">
  <goal name="index&#39;vc" expl="VC for index" proved="true">
- <proof prover="1"><result status="valid" time="0.030000" steps="163"/></proof>
+ <proof prover="0"><result status="valid" time="0.030000" steps="162"/></proof>
  </goal>
 </theory>
 <theory name="BinarySearch_Impl0_Len" proved="true">
  <goal name="len&#39;vc" expl="VC for len" proved="true">
- <proof prover="1"><result status="valid" time="0.020000" steps="164"/></proof>
+ <proof prover="0"><result status="valid" time="0.020000" steps="155"/></proof>
  </goal>
 </theory>
 <theory name="BinarySearch_BinarySearch" proved="true">
  <goal name="binary_search&#39;vc" expl="VC for binary_search" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="binary_search&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="10"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="10"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.006300" steps="13"/></proof>
+  <proof prover="0"><result status="valid" time="0.006300" steps="13"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="24"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="24"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.008696" steps="29"/></proof>
+  <proof prover="0"><result status="valid" time="0.008696" steps="29"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="34"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="34"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.5" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="65"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="64"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.6" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.070000" steps="48"/></proof>
+  <proof prover="0"><result status="valid" time="0.070000" steps="48"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.7" expl="division by zero" proved="true">
-  <proof prover="1"><result status="valid" time="0.020000" steps="51"/></proof>
+  <proof prover="0"><result status="valid" time="0.020000" steps="51"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.8" expl="division by zero" proved="true">
-  <proof prover="1"><result status="valid" time="0.050000" steps="53"/></proof>
+  <proof prover="0"><result status="valid" time="0.050000" steps="53"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.9" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.030000" steps="115"/></proof>
+  <proof prover="0"><result status="valid" time="0.030000" steps="114"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.10" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.040000" steps="562"/></proof>
+  <proof prover="0"><result status="valid" time="0.040000" steps="560"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.030000" steps="149"/></proof>
+  <proof prover="0"><result status="valid" time="0.030000" steps="149"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.12" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.025913" steps="127"/></proof>
+  <proof prover="0"><result status="valid" time="0.025913" steps="127"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.13" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.020000" steps="50"/></proof>
+  <proof prover="0"><result status="valid" time="0.020000" steps="50"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.015004" steps="65"/></proof>
+  <proof prover="0"><result status="valid" time="0.015004" steps="65"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.15" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.060000" steps="87"/></proof>
+  <proof prover="0"><result status="valid" time="0.060000" steps="87"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.16" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.120000" steps="705"/></proof>
+  <proof prover="0"><result status="valid" time="0.120000" steps="694"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.17" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.030000" steps="304"/></proof>
+  <proof prover="0"><result status="valid" time="0.030000" steps="301"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.18" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.120000" steps="1066"/></proof>
+  <proof prover="0"><result status="valid" time="0.120000" steps="1081"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.19" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.161160" steps="2422"/></proof>
+  <proof prover="0"><result status="valid" time="0.161160" steps="2351"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.20" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.090000" steps="777"/></proof>
+  <proof prover="0"><result status="valid" time="0.090000" steps="775"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.21" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.331323" steps="6726"/></proof>
+  <proof prover="0"><result status="valid" time="0.331323" steps="7090"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.22" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.511725" steps="10470"/></proof>
+  <proof prover="0"><result status="valid" time="0.511725" steps="11133"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/bug/173/why3session.xml b/creusot/tests/should_succeed/bug/173/why3session.xml
index 59a9756fe..e8330ec9e 100644
--- a/creusot/tests/should_succeed/bug/173/why3session.xml
+++ b/creusot/tests/should_succeed/bug/173/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="173.mlcfg"/>
 <theory name="C173_Test233" proved="true">
  <goal name="test_233&#39;vc" expl="VC for test_233" proved="true">
- <proof prover="1"><result status="valid" time="0.006587" steps="6"/></proof>
+ <proof prover="0"><result status="valid" time="0.006587" steps="6"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/206/why3session.xml b/creusot/tests/should_succeed/bug/206/why3session.xml
index ed9cac8dd..ffa6864da 100644
--- a/creusot/tests/should_succeed/bug/206/why3session.xml
+++ b/creusot/tests/should_succeed/bug/206/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="206.mlcfg"/>
 <theory name="C206_U2_Impl" proved="true">
  <goal name="u2&#39;vc" expl="VC for u2" proved="true">
- <proof prover="1"><result status="valid" time="0.006573" steps="3"/></proof>
+ <proof prover="0"><result status="valid" time="0.006573" steps="2"/></proof>
  </goal>
 </theory>
 <theory name="C206_Ex" proved="true">
  <goal name="ex&#39;vc" expl="VC for ex" proved="true">
- <proof prover="1"><result status="valid" time="0.006735" steps="3"/></proof>
+ <proof prover="0"><result status="valid" time="0.006735" steps="2"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/206/why3shapes.gz b/creusot/tests/should_succeed/bug/206/why3shapes.gz
index 8f5cb41b3..6bd50039a 100644
Binary files a/creusot/tests/should_succeed/bug/206/why3shapes.gz and b/creusot/tests/should_succeed/bug/206/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/bug/217/why3session.xml b/creusot/tests/should_succeed/bug/217/why3session.xml
index 84cd5ba6f..626a388c9 100644
--- a/creusot/tests/should_succeed/bug/217/why3session.xml
+++ b/creusot/tests/should_succeed/bug/217/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="217.mlcfg"/>
 <theory name="C217_Ex_Impl" proved="true">
  <goal name="ex&#39;vc" expl="VC for ex" proved="true">
- <proof prover="1"><result status="valid" time="0.007474" steps="17"/></proof>
+ <proof prover="0"><result status="valid" time="0.007474" steps="17"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/217/why3shapes.gz b/creusot/tests/should_succeed/bug/217/why3shapes.gz
index e3e9d69c2..9ade06dda 100644
Binary files a/creusot/tests/should_succeed/bug/217/why3shapes.gz and b/creusot/tests/should_succeed/bug/217/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/bug/235/why3session.xml b/creusot/tests/should_succeed/bug/235/why3session.xml
index ce6959ec8..b9ec902f1 100644
--- a/creusot/tests/should_succeed/bug/235/why3session.xml
+++ b/creusot/tests/should_succeed/bug/235/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="235.mlcfg"/>
 <theory name="C235_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.005625" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.005625" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/273/why3session.xml b/creusot/tests/should_succeed/bug/273/why3session.xml
index 0ec6d430e..58a649c88 100644
--- a/creusot/tests/should_succeed/bug/273/why3session.xml
+++ b/creusot/tests/should_succeed/bug/273/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="273.mlcfg"/>
 <theory name="C273_Ex" proved="true">
  <goal name="ex&#39;vc" expl="VC for ex" proved="true">
- <proof prover="1"><result status="valid" time="0.005180" steps="8"/></proof>
+ <proof prover="0"><result status="valid" time="0.005180" steps="8"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/395/why3session.xml b/creusot/tests/should_succeed/bug/395/why3session.xml
index 3ee736c29..947eb7e8f 100644
--- a/creusot/tests/should_succeed/bug/395/why3session.xml
+++ b/creusot/tests/should_succeed/bug/395/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="395.mlcfg"/>
 <theory name="C395_SignedDivision" proved="true">
  <goal name="signed_division&#39;vc" expl="VC for signed_division" proved="true">
- <proof prover="1"><result status="valid" time="0.014763" steps="403"/></proof>
+ <proof prover="0"><result status="valid" time="0.014763" steps="404"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/463/why3session.xml b/creusot/tests/should_succeed/bug/463/why3session.xml
index be56cb995..5cab4bbae 100644
--- a/creusot/tests/should_succeed/bug/463/why3session.xml
+++ b/creusot/tests/should_succeed/bug/463/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="463.mlcfg"/>
 <theory name="C463_Test_Closure0" proved="true">
  <goal name="c463_Test_Closure0&#39;vc" expl="VC for c463_Test_Closure0" proved="true">
- <proof prover="1"><result status="valid" time="0.005976" steps="9"/></proof>
+ <proof prover="0"><result status="valid" time="0.005976" steps="9"/></proof>
  </goal>
 </theory>
 <theory name="C463_Test" proved="true">
  <goal name="test&#39;vc" expl="VC for test" proved="true">
- <proof prover="1"><result status="valid" time="0.007604" steps="6"/></proof>
+ <proof prover="0"><result status="valid" time="0.007604" steps="6"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/545/why3session.xml b/creusot/tests/should_succeed/bug/545/why3session.xml
index cbf628359..3e92c6a07 100644
--- a/creusot/tests/should_succeed/bug/545/why3session.xml
+++ b/creusot/tests/should_succeed/bug/545/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="545.mlcfg"/>
 <theory name="C545_NegativeIsNegative" proved="true">
  <goal name="negative_is_negative&#39;vc" expl="VC for negative_is_negative" proved="true">
- <proof prover="1"><result status="valid" time="0.005532" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.005532" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/552/why3session.xml b/creusot/tests/should_succeed/bug/552/why3session.xml
index 5afa7e31c..bba975ab4 100644
--- a/creusot/tests/should_succeed/bug/552/why3session.xml
+++ b/creusot/tests/should_succeed/bug/552/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="552.mlcfg"/>
 <theory name="C552_Impl0_Step" proved="true">
  <goal name="step&#39;vc" expl="VC for step" proved="true">
- <proof prover="1"><result status="valid" time="0.004359" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.004359" steps="0"/></proof>
  </goal>
 </theory>
 <theory name="C552_Impl0" proved="true">
  <goal name="step_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.004977" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.004977" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/682/why3session.xml b/creusot/tests/should_succeed/bug/682/why3session.xml
index 112c4a975..243670953 100644
--- a/creusot/tests/should_succeed/bug/682/why3session.xml
+++ b/creusot/tests/should_succeed/bug/682/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="682.mlcfg"/>
 <theory name="C682_AddSome" proved="true">
  <goal name="add_some&#39;vc" expl="VC for add_some" proved="true">
- <proof prover="1"><result status="valid" time="0.012416" steps="196"/></proof>
+ <proof prover="0"><result status="valid" time="0.012416" steps="196"/></proof>
  </goal>
 </theory>
 <theory name="C682_Foo" proved="true">
  <goal name="foo&#39;vc" expl="VC for foo" proved="true">
- <proof prover="1"><result status="valid" time="0.018181" steps="436"/></proof>
+ <proof prover="0"><result status="valid" time="0.018181" steps="442"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/874/why3session.xml b/creusot/tests/should_succeed/bug/874/why3session.xml
index 507eab598..d01aeea11 100644
--- a/creusot/tests/should_succeed/bug/874/why3session.xml
+++ b/creusot/tests/should_succeed/bug/874/why3session.xml
@@ -2,33 +2,37 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Z3" version="4.12.2" timelimit="30" steplimit="0" memlimit="4000"/>
+<prover id="2" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="874.mlcfg"/>
 <theory name="C874_CanExtend" proved="true">
  <goal name="can_extend&#39;vc" expl="VC for can_extend" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="can_extend&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.013083" steps="18"/></proof>
+  <proof prover="2"><result status="valid" time="0.013083" steps="18"/></proof>
   </goal>
   <goal name="can_extend&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.012574" steps="40"/></proof>
+  <proof prover="2"><result status="valid" time="0.012574" steps="40"/></proof>
   </goal>
   <goal name="can_extend&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.009609" steps="30"/></proof>
+  <proof prover="2"><result status="valid" time="0.009609" steps="30"/></proof>
   </goal>
   <goal name="can_extend&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010590" steps="48"/></proof>
+  <proof prover="2"><result status="valid" time="0.010590" steps="48"/></proof>
   </goal>
   <goal name="can_extend&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.008144" steps="32"/></proof>
+  <proof prover="2"><result status="valid" time="0.008144" steps="32"/></proof>
   </goal>
   <goal name="can_extend&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010587" steps="63"/></proof>
+  <proof prover="2"><result status="valid" time="0.010587" steps="63"/></proof>
   </goal>
   <goal name="can_extend&#39;vc.6" expl="assertion" proved="true">
-  <proof prover="0"><result status="valid" time="0.060098" steps="292335"/></proof>
+  <transf name="split_vc" proved="true" >
+   <goal name="can_extend&#39;vc.6.0" expl="assertion" proved="true">
+   <proof prover="1"><result status="valid" time="9.175014" steps="29143030"/></proof>
+   </goal>
+  </transf>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/bug/874/why3shapes.gz b/creusot/tests/should_succeed/bug/874/why3shapes.gz
index 4d962f2ae..f409e6a0a 100644
Binary files a/creusot/tests/should_succeed/bug/874/why3shapes.gz and b/creusot/tests/should_succeed/bug/874/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/bug/eq_panic/why3session.xml b/creusot/tests/should_succeed/bug/eq_panic/why3session.xml
index 907d1302e..b36230b2b 100644
--- a/creusot/tests/should_succeed/bug/eq_panic/why3session.xml
+++ b/creusot/tests/should_succeed/bug/eq_panic/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="eq_panic.mlcfg"/>
 <theory name="EqPanic_Omg" proved="true">
  <goal name="omg&#39;vc" expl="VC for omg" proved="true">
- <proof prover="0"><result status="valid" time="0.005170" steps="11"/></proof>
+ <proof prover="1"><result status="valid" time="0.005170" steps="11"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/minus_assoc/why3session.xml b/creusot/tests/should_succeed/bug/minus_assoc/why3session.xml
index 00ca672f4..51a7a8ca2 100644
--- a/creusot/tests/should_succeed/bug/minus_assoc/why3session.xml
+++ b/creusot/tests/should_succeed/bug/minus_assoc/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="minus_assoc.mlcfg"/>
 <theory name="MinusAssoc_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.007153" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.007153" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/pure_neq/why3session.xml b/creusot/tests/should_succeed/bug/pure_neq/why3session.xml
index c3d6179cd..58a8feb93 100644
--- a/creusot/tests/should_succeed/bug/pure_neq/why3session.xml
+++ b/creusot/tests/should_succeed/bug/pure_neq/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="pure_neq.mlcfg"/>
 <theory name="PureNeq_F_Impl" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.006019" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.006019" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/two_phase/why3session.xml b/creusot/tests/should_succeed/bug/two_phase/why3session.xml
index 21d4f35d6..310ef881c 100644
--- a/creusot/tests/should_succeed/bug/two_phase/why3session.xml
+++ b/creusot/tests/should_succeed/bug/two_phase/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="two_phase.mlcfg"/>
 <theory name="TwoPhase_Test" proved="true">
  <goal name="test&#39;vc" expl="VC for test" proved="true">
- <proof prover="1"><result status="valid" time="0.019451" steps="125"/></proof>
+ <proof prover="0"><result status="valid" time="0.019451" steps="125"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/bug/two_phase/why3shapes.gz b/creusot/tests/should_succeed/bug/two_phase/why3shapes.gz
index 78e58f241..83a203c16 100644
Binary files a/creusot/tests/should_succeed/bug/two_phase/why3shapes.gz and b/creusot/tests/should_succeed/bug/two_phase/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/cell/01/why3session.xml b/creusot/tests/should_succeed/cell/01/why3session.xml
index 2cef2f2d4..ae42d1aaa 100644
--- a/creusot/tests/should_succeed/cell/01/why3session.xml
+++ b/creusot/tests/should_succeed/cell/01/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="01.mlcfg"/>
 <theory name="C01_AddsTwo" proved="true">
  <goal name="adds_two&#39;vc" expl="VC for adds_two" proved="true">
- <proof prover="1"><result status="valid" time="0.033868" steps="717"/></proof>
+ <proof prover="0"><result status="valid" time="0.033868" steps="692"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/cell/02/why3session.xml b/creusot/tests/should_succeed/cell/02/why3session.xml
index f12072433..a7ff0749c 100644
--- a/creusot/tests/should_succeed/cell/02/why3session.xml
+++ b/creusot/tests/should_succeed/cell/02/why3session.xml
@@ -2,65 +2,64 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="3" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="4" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="5" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="02.mlcfg"/>
 <theory name="C02_Fib_Impl" proved="true">
  <goal name="fib&#39;vc" expl="VC for fib" proved="true">
- <proof prover="0"><result status="valid" time="0.008370" steps="451"/></proof>
+ <proof prover="4"><result status="valid" time="0.008499" steps="428"/></proof>
  </goal>
 </theory>
 <theory name="C02_LemmaFibBound_Impl" proved="true">
  <goal name="lemma_fib_bound&#39;vc" expl="VC for lemma_fib_bound" proved="true">
- <proof prover="0"><result status="valid" time="0.012781" steps="9637"/></proof>
+ <proof prover="4"><result status="valid" time="0.010987" steps="9016"/></proof>
  </goal>
 </theory>
 <theory name="C02_FibMemo" proved="true">
  <goal name="fib_memo&#39;vc" expl="VC for fib_memo" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="fib_memo&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.008535" steps="10"/></proof>
+  <proof prover="5"><result status="valid" time="0.008535" steps="10"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.015501" steps="23"/></proof>
-  <proof prover="3"><result status="valid" time="0.064765" steps="70754"/></proof>
+  <proof prover="4"><result status="valid" time="0.064765" steps="71155"/></proof>
+  <proof prover="5"><result status="valid" time="0.015501" steps="22"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.012298" steps="25"/></proof>
-  <proof prover="3"><result status="valid" time="0.021326" steps="70817"/></proof>
+  <proof prover="4"><result status="valid" time="0.021326" steps="71218"/></proof>
+  <proof prover="5"><result status="valid" time="0.012298" steps="23"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.008697" steps="14"/></proof>
+  <proof prover="5"><result status="valid" time="0.008697" steps="14"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.4" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.010993" steps="51"/></proof>
+  <proof prover="5"><result status="valid" time="0.010993" steps="51"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009887" steps="34"/></proof>
+  <proof prover="5"><result status="valid" time="0.009887" steps="34"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009296" steps="34"/></proof>
+  <proof prover="5"><result status="valid" time="0.009296" steps="34"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009368" steps="35"/></proof>
+  <proof prover="5"><result status="valid" time="0.009368" steps="35"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.8" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.011951" steps="76"/></proof>
+  <proof prover="5"><result status="valid" time="0.011951" steps="75"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009451" steps="38"/></proof>
+  <proof prover="5"><result status="valid" time="0.009451" steps="38"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009582" steps="38"/></proof>
+  <proof prover="5"><result status="valid" time="0.009582" steps="38"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009606" steps="39"/></proof>
+  <proof prover="5"><result status="valid" time="0.009606" steps="39"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.12" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.103941" steps="1037"/></proof>
+  <proof prover="5"><result status="valid" time="0.103941" steps="1036"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.13" expl="assertion" proved="true">
   <transf name="split_vc" proved="true" >
@@ -69,7 +68,7 @@
     <goal name="fib_memo&#39;vc.13.0.0" expl="assertion" proved="true">
     <transf name="split_vc" proved="true" >
      <goal name="fib_memo&#39;vc.13.0.0.0" expl="assertion" proved="true">
-     <proof prover="3"><result status="valid" time="0.024054" steps="89767"/></proof>
+     <proof prover="4"><result status="valid" time="0.024054" steps="92696"/></proof>
      </goal>
     </transf>
     </goal>
@@ -80,10 +79,10 @@
     <goal name="fib_memo&#39;vc.13.1.0" expl="assertion" proved="true">
     <transf name="split_vc" proved="true" >
      <goal name="fib_memo&#39;vc.13.1.0.0" expl="assertion" proved="true">
-     <proof prover="2"><result status="valid" time="0.212541" steps="1838"/></proof>
+     <proof prover="5"><result status="valid" time="0.212541" steps="1837"/></proof>
      </goal>
      <goal name="fib_memo&#39;vc.13.1.0.1" expl="assertion" proved="true">
-     <proof prover="2"><result status="valid" time="0.043215" steps="247"/></proof>
+     <proof prover="5"><result status="valid" time="0.043215" steps="246"/></proof>
      </goal>
     </transf>
     </goal>
@@ -92,28 +91,28 @@
   </transf>
   </goal>
   <goal name="fib_memo&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.028068" steps="18"/></proof>
-  <proof prover="3"><result status="valid" time="0.011911" steps="8451"/></proof>
+  <proof prover="4"><result status="valid" time="0.011911" steps="8814"/></proof>
+  <proof prover="5"><result status="valid" time="0.028068" steps="18"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009702" steps="55"/></proof>
+  <proof prover="5"><result status="valid" time="0.009702" steps="55"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.068972" steps="13959"/></proof>
-  <proof prover="2"><result status="valid" time="0.029729" steps="57"/></proof>
+  <proof prover="1"><result status="valid" time="0.068972" steps="13689"/></proof>
+  <proof prover="5"><result status="valid" time="0.029729" steps="56"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.17" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.029642" steps="334"/></proof>
+  <proof prover="5"><result status="valid" time="0.029642" steps="333"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.18" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.117430" steps="23"/></proof>
+  <proof prover="5"><result status="valid" time="0.117430" steps="23"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.19" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.022739" steps="61"/></proof>
-  <proof prover="3"><result status="valid" time="0.023987" steps="87147"/></proof>
+  <proof prover="4"><result status="valid" time="0.023987" steps="89729"/></proof>
+  <proof prover="5"><result status="valid" time="0.022739" steps="59"/></proof>
   </goal>
   <goal name="fib_memo&#39;vc.20" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.107580" steps="16561"/></proof>
+  <proof prover="1"><result status="valid" time="0.107580" steps="16279"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/cell/02/why3shapes.gz b/creusot/tests/should_succeed/cell/02/why3shapes.gz
index bb2b0a24c..74d9335ca 100644
Binary files a/creusot/tests/should_succeed/cell/02/why3shapes.gz and b/creusot/tests/should_succeed/cell/02/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/checked_ops/why3session.xml b/creusot/tests/should_succeed/checked_ops/why3session.xml
index 08b8b7fdc..ac3172c6f 100644
--- a/creusot/tests/should_succeed/checked_ops/why3session.xml
+++ b/creusot/tests/should_succeed/checked_ops/why3session.xml
@@ -2,7 +2,7 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="4" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
@@ -64,12 +64,12 @@
 </theory>
 <theory name="CheckedOps_TestU8DivExample" proved="true">
  <goal name="test_u8_div_example&#39;vc" expl="VC for test_u8_div_example" proved="true">
- <proof prover="1"><result status="valid" time="0.016545" steps="23295"/></proof>
+ <proof prover="0"><result status="valid" time="0.013333" steps="19296"/></proof>
  </goal>
 </theory>
 <theory name="CheckedOps_TestU8DivNoOverflow" proved="true">
  <goal name="test_u8_div_no_overflow&#39;vc" expl="VC for test_u8_div_no_overflow" proved="true">
- <proof prover="1"><result status="valid" time="0.020213" steps="32863"/></proof>
+ <proof prover="0"><result status="valid" time="0.019153" steps="34198"/></proof>
  </goal>
 </theory>
 <theory name="CheckedOps_TestU8DivZero" proved="true">
@@ -144,12 +144,12 @@
 </theory>
 <theory name="CheckedOps_TestI8DivExample" proved="true">
  <goal name="test_i8_div_example&#39;vc" expl="VC for test_i8_div_example" proved="true">
- <proof prover="1"><result status="valid" time="0.022312" steps="61042"/></proof>
+ <proof prover="0"><result status="valid" time="0.023227" steps="46438"/></proof>
  </goal>
 </theory>
 <theory name="CheckedOps_TestI8DivNoOverflow" proved="true">
  <goal name="test_i8_div_no_overflow&#39;vc" expl="VC for test_i8_div_no_overflow" proved="true">
- <proof prover="1"><result status="valid" time="0.019614" steps="45419"/></proof>
+ <proof prover="0"><result status="valid" time="0.024961" steps="45642"/></proof>
  </goal>
 </theory>
 <theory name="CheckedOps_TestI8DivZero" proved="true">
diff --git a/creusot/tests/should_succeed/clones/02/why3session.xml b/creusot/tests/should_succeed/clones/02/why3session.xml
index f9de16def..4234c5f14 100644
--- a/creusot/tests/should_succeed/clones/02/why3session.xml
+++ b/creusot/tests/should_succeed/clones/02/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="02.mlcfg"/>
 <theory name="C02_Program" proved="true">
  <goal name="program&#39;vc" expl="VC for program" proved="true">
- <proof prover="1"><result status="valid" time="0.004615" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.004615" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/clones/03/why3session.xml b/creusot/tests/should_succeed/clones/03/why3session.xml
index f49407661..694690e97 100644
--- a/creusot/tests/should_succeed/clones/03/why3session.xml
+++ b/creusot/tests/should_succeed/clones/03/why3session.xml
@@ -2,13 +2,13 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="03.mlcfg"/>
 <theory name="C03_Prog" proved="true">
  <goal name="prog&#39;vc" expl="VC for prog" proved="true">
- <proof prover="0"><result status="valid" time="0.007321" steps="15"/></proof>
+ <proof prover="2"><result status="valid" time="0.010906" steps="15"/></proof>
  </goal>
 </theory>
 <theory name="C03_Prog2" proved="true">
diff --git a/creusot/tests/should_succeed/closures/06_fn_specs/why3session.xml b/creusot/tests/should_succeed/closures/06_fn_specs/why3session.xml
index 2596febb8..980623ad9 100644
--- a/creusot/tests/should_succeed/closures/06_fn_specs/why3session.xml
+++ b/creusot/tests/should_succeed/closures/06_fn_specs/why3session.xml
@@ -3,7 +3,7 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="06_fn_specs.mlcfg"/>
 <theory name="C06FnSpecs_Weaken3" proved="true">
@@ -18,7 +18,7 @@
 </theory>
 <theory name="C06FnSpecs_Weaken" proved="true">
  <goal name="weaken&#39;vc" expl="VC for weaken" proved="true">
- <proof prover="1"><result status="valid" time="0.011105" steps="7988"/></proof>
+ <proof prover="2"><result status="valid" time="0.012255" steps="7305"/></proof>
  </goal>
 </theory>
 <theory name="C06FnSpecs_Weaken3Std" proved="true">
@@ -33,7 +33,7 @@
 </theory>
 <theory name="C06FnSpecs_WeakenStd" proved="true">
  <goal name="weaken_std&#39;vc" expl="VC for weaken_std" proved="true">
- <proof prover="1"><result status="valid" time="0.009444" steps="7988"/></proof>
+ <proof prover="2"><result status="valid" time="0.012917" steps="7305"/></proof>
  </goal>
 </theory>
 <theory name="C06FnSpecs_FnOnceUser" proved="true">
diff --git a/creusot/tests/should_succeed/closures/07_mutable_capture/why3session.xml b/creusot/tests/should_succeed/closures/07_mutable_capture/why3session.xml
index 279be367c..50360b73d 100644
--- a/creusot/tests/should_succeed/closures/07_mutable_capture/why3session.xml
+++ b/creusot/tests/should_succeed/closures/07_mutable_capture/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="07_mutable_capture.mlcfg"/>
 <theory name="C07MutableCapture_TestFnmut_Closure1" proved="true">
  <goal name="c07MutableCapture_TestFnmut_Closure1&#39;vc" expl="VC for c07MutableCapture_TestFnmut_Closure1" proved="true">
- <proof prover="0"><result status="valid" time="0.010494" steps="132"/></proof>
+ <proof prover="1"><result status="valid" time="0.010494" steps="132"/></proof>
  </goal>
 </theory>
 <theory name="C07MutableCapture_TestFnmut" proved="true">
  <goal name="test_fnmut&#39;vc" expl="VC for test_fnmut" proved="true">
- <proof prover="0"><result status="valid" time="0.011714" steps="110"/></proof>
+ <proof prover="1"><result status="valid" time="0.011714" steps="110"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/constrained_types/why3session.xml b/creusot/tests/should_succeed/constrained_types/why3session.xml
index 9472fd004..039941142 100644
--- a/creusot/tests/should_succeed/constrained_types/why3session.xml
+++ b/creusot/tests/should_succeed/constrained_types/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="constrained_types.mlcfg"/>
 <theory name="ConstrainedTypes_UsesConcreteInstance" proved="true">
  <goal name="uses_concrete_instance&#39;vc" expl="VC for uses_concrete_instance" proved="true">
- <proof prover="0"><result status="valid" time="0.006904" steps="7"/></proof>
+ <proof prover="1"><result status="valid" time="0.006904" steps="7"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/drop_pair/why3session.xml b/creusot/tests/should_succeed/drop_pair/why3session.xml
index d12ee4a34..b1e6a301c 100644
--- a/creusot/tests/should_succeed/drop_pair/why3session.xml
+++ b/creusot/tests/should_succeed/drop_pair/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="drop_pair.mlcfg"/>
 <theory name="DropPair_DropPair" proved="true">
  <goal name="drop_pair&#39;vc" expl="VC for drop_pair" proved="true">
- <proof prover="1"><result status="valid" time="0.006029" steps="17"/></proof>
+ <proof prover="0"><result status="valid" time="0.006029" steps="17"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/filter_positive/why3session.xml b/creusot/tests/should_succeed/filter_positive/why3session.xml
index 8b6befada..436d60ab3 100644
--- a/creusot/tests/should_succeed/filter_positive/why3session.xml
+++ b/creusot/tests/should_succeed/filter_positive/why3session.xml
@@ -2,29 +2,28 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="4" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="filter_positive.mlcfg"/>
 <theory name="FilterPositive_NumOfPos_Impl" proved="true">
  <goal name="num_of_pos&#39;vc" expl="VC for num_of_pos" proved="true">
- <proof prover="1"><result status="valid" time="0.006805" steps="2"/></proof>
+ <proof prover="4"><result status="valid" time="0.006805" steps="2"/></proof>
  </goal>
 </theory>
 <theory name="FilterPositive_LemmaNumOfPosIncreasing_Impl" proved="true">
  <goal name="lemma_num_of_pos_increasing&#39;vc" expl="VC for lemma_num_of_pos_increasing" proved="true">
- <proof prover="0"><result status="valid" time="0.015949" steps="37401"/></proof>
+ <proof prover="3"><result status="valid" time="0.015897" steps="39467"/></proof>
  </goal>
 </theory>
 <theory name="FilterPositive_LemmaNumOfPosStrictlyIncreasing_Impl" proved="true">
  <goal name="lemma_num_of_pos_strictly_increasing&#39;vc" expl="VC for lemma_num_of_pos_strictly_increasing" proved="true">
- <proof prover="1"><result status="valid" time="0.008797" steps="45"/></proof>
+ <proof prover="4"><result status="valid" time="0.008797" steps="32"/></proof>
  </goal>
 </theory>
 <theory name="FilterPositive_M" proved="true">
  <goal name="m&#39;vc" expl="VC for m" proved="true">
- <proof prover="2"><result status="valid" time="0.034295" steps="125855"/></proof>
+ <proof prover="3"><result status="valid" time="0.034295" steps="113940"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/filter_positive/why3shapes.gz b/creusot/tests/should_succeed/filter_positive/why3shapes.gz
index 71e53ebdb..8154971b2 100644
Binary files a/creusot/tests/should_succeed/filter_positive/why3shapes.gz and b/creusot/tests/should_succeed/filter_positive/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/hashmap/why3session.xml b/creusot/tests/should_succeed/hashmap/why3session.xml
index b4e5cd3df..67686ec0b 100644
--- a/creusot/tests/should_succeed/hashmap/why3session.xml
+++ b/creusot/tests/should_succeed/hashmap/why3session.xml
@@ -2,73 +2,71 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="3" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="6" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="hashmap.mlcfg"/>
 <theory name="Hashmap_Impl2_Hash" proved="true">
  <goal name="hash&#39;vc" expl="VC for hash" proved="true">
- <proof prover="6"><result status="valid" time="0.000000" steps="16"/></proof>
+ <proof prover="3"><result status="valid" time="0.000000" steps="16"/></proof>
  </goal>
 </theory>
 <theory name="Hashmap_Impl5_New" proved="true">
  <goal name="new&#39;vc" expl="VC for new" proved="true">
- <proof prover="6"><result status="valid" time="0.020000" steps="337"/></proof>
+ <proof prover="3"><result status="valid" time="0.020000" steps="336"/></proof>
  </goal>
 </theory>
 <theory name="Hashmap_Impl5_Add" proved="true">
  <goal name="add&#39;vc" expl="VC for add" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="add&#39;vc.0" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.017641" steps="16"/></proof>
+  <proof prover="3"><result status="valid" time="0.017641" steps="16"/></proof>
   </goal>
   <goal name="add&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.014111" steps="20"/></proof>
+  <proof prover="3"><result status="valid" time="0.014111" steps="20"/></proof>
   </goal>
   <goal name="add&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.013861" steps="22"/></proof>
+  <proof prover="3"><result status="valid" time="0.013861" steps="22"/></proof>
   </goal>
   <goal name="add&#39;vc.3" expl="remainder by zero" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="45"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="45"/></proof>
   </goal>
   <goal name="add&#39;vc.4" expl="integer overflow" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="41"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="39"/></proof>
   </goal>
   <goal name="add&#39;vc.5" expl="division by zero" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="34"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="34"/></proof>
   </goal>
   <goal name="add&#39;vc.6" expl="integer overflow" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="253"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="252"/></proof>
   </goal>
   <goal name="add&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.020000" steps="346"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="345"/></proof>
   </goal>
   <goal name="add&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.023065" steps="83"/></proof>
+  <proof prover="3"><result status="valid" time="0.023065" steps="82"/></proof>
   </goal>
   <goal name="add&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.024293" steps="83"/></proof>
+  <proof prover="3"><result status="valid" time="0.024293" steps="83"/></proof>
   </goal>
   <goal name="add&#39;vc.10" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.033878" steps="100"/></proof>
+  <proof prover="3"><result status="valid" time="0.033878" steps="99"/></proof>
   </goal>
   <goal name="add&#39;vc.11" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.026823" steps="103"/></proof>
+  <proof prover="3"><result status="valid" time="0.026823" steps="102"/></proof>
   </goal>
   <goal name="add&#39;vc.12" expl="loop invariant init" proved="true">
   <proof prover="3"><result status="valid" time="0.010000" steps="484"/></proof>
   </goal>
   <goal name="add&#39;vc.13" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.117533" steps="115323"/></proof>
+  <proof prover="0"><result status="valid" time="0.117533" steps="118256"/></proof>
   </goal>
   <goal name="add&#39;vc.14" expl="loop invariant init" proved="true">
-  <proof prover="3"><result status="valid" time="0.010000" steps="150"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="148"/></proof>
   </goal>
   <goal name="add&#39;vc.15" expl="loop invariant init" proved="true">
-  <proof prover="3"><result status="valid" time="0.010000" steps="153"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="152"/></proof>
   </goal>
   <goal name="add&#39;vc.16" expl="loop invariant init" proved="true">
   <proof prover="3"><result status="valid" time="0.020000" steps="519"/></proof>
@@ -80,61 +78,61 @@
   <proof prover="3"><result status="valid" time="0.050551" steps="203"/></proof>
   </goal>
   <goal name="add&#39;vc.19" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.046253" steps="206"/></proof>
+  <proof prover="3"><result status="valid" time="0.046253" steps="204"/></proof>
   </goal>
   <goal name="add&#39;vc.20" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.037622" steps="205"/></proof>
+  <proof prover="3"><result status="valid" time="0.037622" steps="204"/></proof>
   </goal>
   <goal name="add&#39;vc.21" expl="type invariant" proved="true">
   <proof prover="3"><result status="valid" time="0.026727" steps="207"/></proof>
   </goal>
   <goal name="add&#39;vc.22" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.040909" steps="225"/></proof>
+  <proof prover="3"><result status="valid" time="0.040909" steps="224"/></proof>
   </goal>
   <goal name="add&#39;vc.23" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.033278" steps="228"/></proof>
+  <proof prover="3"><result status="valid" time="0.033278" steps="226"/></proof>
   </goal>
   <goal name="add&#39;vc.24" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.046851" steps="228"/></proof>
+  <proof prover="3"><result status="valid" time="0.046851" steps="227"/></proof>
   </goal>
   <goal name="add&#39;vc.25" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.343533" steps="36997"/></proof>
+  <proof prover="1"><result status="valid" time="0.120764" steps="36643"/></proof>
   </goal>
   <goal name="add&#39;vc.26" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.046695" steps="143325"/></proof>
+  <proof prover="0"><result status="valid" time="0.046695" steps="145258"/></proof>
   </goal>
   <goal name="add&#39;vc.27" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.030000" steps="131501"/></proof>
+  <proof prover="0"><result status="valid" time="0.030000" steps="134643"/></proof>
   </goal>
   <goal name="add&#39;vc.28" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.259557" steps="36092"/></proof>
+  <proof prover="1"><result status="valid" time="0.112822" steps="35794"/></proof>
   </goal>
   <goal name="add&#39;vc.29" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="0.030000" steps="430"/></proof>
+  <proof prover="3"><result status="valid" time="0.030000" steps="429"/></proof>
   </goal>
   <goal name="add&#39;vc.30" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.417588" steps="48571"/></proof>
+  <proof prover="1"><result status="valid" time="0.160186" steps="48173"/></proof>
   </goal>
   <goal name="add&#39;vc.31" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.026545" steps="208"/></proof>
+  <proof prover="3"><result status="valid" time="0.026545" steps="207"/></proof>
   </goal>
   <goal name="add&#39;vc.32" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.026865" steps="130"/></proof>
+  <proof prover="3"><result status="valid" time="0.026865" steps="128"/></proof>
   </goal>
   <goal name="add&#39;vc.33" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.023273" steps="131"/></proof>
+  <proof prover="3"><result status="valid" time="0.023273" steps="130"/></proof>
   </goal>
   <goal name="add&#39;vc.34" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.029787" steps="135"/></proof>
+  <proof prover="3"><result status="valid" time="0.029787" steps="134"/></proof>
   </goal>
   <goal name="add&#39;vc.35" expl="type invariant" proved="true">
   <proof prover="3"><result status="valid" time="0.038618" steps="218"/></proof>
   </goal>
   <goal name="add&#39;vc.36" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.034607" steps="222"/></proof>
+  <proof prover="3"><result status="valid" time="0.034607" steps="221"/></proof>
   </goal>
   <goal name="add&#39;vc.37" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.027034" steps="227"/></proof>
+  <proof prover="3"><result status="valid" time="0.027034" steps="226"/></proof>
   </goal>
   <goal name="add&#39;vc.38" expl="type invariant" proved="true">
   <proof prover="3"><result status="valid" time="0.039024" steps="225"/></proof>
@@ -151,24 +149,24 @@
      <goal name="add&#39;vc.39.0.1.0" expl="VC for add" proved="true">
      <transf name="inline_goal" proved="true" >
       <goal name="add&#39;vc.39.0.1.0.0" expl="VC for add" proved="true">
-      <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="2.774888" steps="38903"/></proof>
+      <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="1.225018" steps="38891"/></proof>
       </goal>
      </transf>
      </goal>
     </transf>
     </goal>
     <goal name="add&#39;vc.39.0.2" expl="VC for add" proved="true">
-    <proof prover="1"><result status="valid" time="0.445436" steps="45935"/></proof>
+    <proof prover="1"><result status="valid" time="0.164103" steps="45887"/></proof>
     </goal>
    </transf>
    </goal>
   </transf>
   </goal>
   <goal name="add&#39;vc.40" expl="unreachable point" proved="true">
-  <proof prover="3"><result status="valid" time="0.030000" steps="314"/></proof>
+  <proof prover="3"><result status="valid" time="0.030000" steps="313"/></proof>
   </goal>
   <goal name="add&#39;vc.41" expl="unreachable point" proved="true">
-  <proof prover="3"><result status="valid" time="0.020000" steps="249"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="247"/></proof>
   </goal>
   <goal name="add&#39;vc.42" expl="unreachable point" proved="true">
   <proof prover="3"><result status="valid" time="0.020000" steps="179"/></proof>
@@ -183,13 +181,13 @@
   <proof prover="3"><result status="valid" time="0.033467" steps="123"/></proof>
   </goal>
   <goal name="add&#39;vc.46" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.041230" steps="126"/></proof>
+  <proof prover="3"><result status="valid" time="0.041230" steps="125"/></proof>
   </goal>
   <goal name="add&#39;vc.47" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.038332" steps="128"/></proof>
+  <proof prover="3"><result status="valid" time="0.038332" steps="127"/></proof>
   </goal>
   <goal name="add&#39;vc.48" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.037778" steps="130"/></proof>
+  <proof prover="3"><result status="valid" time="0.037778" steps="129"/></proof>
   </goal>
   <goal name="add&#39;vc.49" expl="assertion" proved="true">
   <transf name="inline_goal" proved="true" >
@@ -203,21 +201,21 @@
      <goal name="add&#39;vc.49.0.1.0" expl="VC for add" proved="true">
      <transf name="inline_goal" proved="true" >
       <goal name="add&#39;vc.49.0.1.0.0" expl="VC for add" proved="true">
-      <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="1.300540" steps="13603"/></proof>
+      <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="0.471617" steps="13603"/></proof>
       </goal>
      </transf>
      </goal>
     </transf>
     </goal>
     <goal name="add&#39;vc.49.0.2" expl="VC for add" proved="true">
-    <proof prover="3"><result status="valid" time="0.441134" steps="2893"/></proof>
+    <proof prover="3"><result status="valid" time="0.104799" steps="2893"/></proof>
     </goal>
    </transf>
    </goal>
   </transf>
   </goal>
   <goal name="add&#39;vc.50" expl="postcondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.244643" steps="366947"/></proof>
+  <proof prover="0"><result status="valid" time="0.070618" steps="343075"/></proof>
   </goal>
   <goal name="add&#39;vc.51" expl="postcondition" proved="true">
   <transf name="split_vc" proved="true" >
@@ -234,7 +232,7 @@
         <goal name="add&#39;vc.51.0.0.0.0.0.0" expl="postcondition" proved="true">
         <transf name="split_all_full" proved="true" >
          <goal name="add&#39;vc.51.0.0.0.0.0.0.0" expl="postcondition" proved="true">
-         <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="1.764772" steps="25034"/></proof>
+         <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="0.815541" steps="25000"/></proof>
          </goal>
         </transf>
         </goal>
@@ -249,7 +247,7 @@
    </transf>
    </goal>
    <goal name="add&#39;vc.51.1" expl="postcondition" proved="true">
-   <proof prover="3"><result status="valid" time="0.627746" steps="7906"/></proof>
+   <proof prover="3"><result status="valid" time="0.240538" steps="7905"/></proof>
    </goal>
   </transf>
   </goal>
@@ -260,85 +258,85 @@
  <goal name="get&#39;vc" expl="VC for get" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="get&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.021140" steps="12"/></proof>
+  <proof prover="3"><result status="valid" time="0.021140" steps="12"/></proof>
   </goal>
   <goal name="get&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.023465" steps="16"/></proof>
+  <proof prover="3"><result status="valid" time="0.023465" steps="15"/></proof>
   </goal>
   <goal name="get&#39;vc.2" expl="remainder by zero" proved="true">
-  <proof prover="6"><result status="valid" time="0.040109" steps="54"/></proof>
+  <proof prover="3"><result status="valid" time="0.040109" steps="54"/></proof>
   </goal>
   <goal name="get&#39;vc.3" expl="integer overflow" proved="true">
-  <proof prover="6"><result status="valid" time="0.030489" steps="28"/></proof>
+  <proof prover="3"><result status="valid" time="0.030489" steps="27"/></proof>
   </goal>
   <goal name="get&#39;vc.4" expl="division by zero" proved="true">
-  <proof prover="6"><result status="valid" time="0.029645" steps="24"/></proof>
+  <proof prover="3"><result status="valid" time="0.029645" steps="24"/></proof>
   </goal>
   <goal name="get&#39;vc.5" expl="integer overflow" proved="true">
-  <proof prover="6"><result status="valid" time="0.052343" steps="217"/></proof>
+  <proof prover="3"><result status="valid" time="0.052343" steps="216"/></proof>
   </goal>
   <goal name="get&#39;vc.6" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.020145" steps="26"/></proof>
+  <proof prover="3"><result status="valid" time="0.020145" steps="26"/></proof>
   </goal>
   <goal name="get&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.047542" steps="252"/></proof>
+  <proof prover="3"><result status="valid" time="0.047542" steps="251"/></proof>
   </goal>
   <goal name="get&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.034683" steps="51"/></proof>
+  <proof prover="3"><result status="valid" time="0.034683" steps="50"/></proof>
   </goal>
   <goal name="get&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.025050" steps="53"/></proof>
+  <proof prover="3"><result status="valid" time="0.025050" steps="51"/></proof>
   </goal>
   <goal name="get&#39;vc.10" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.037210" steps="34"/></proof>
+  <proof prover="3"><result status="valid" time="0.037210" steps="34"/></proof>
   </goal>
   <goal name="get&#39;vc.11" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.049996" steps="251"/></proof>
+  <proof prover="3"><result status="valid" time="0.049996" steps="251"/></proof>
   </goal>
   <goal name="get&#39;vc.12" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.024471" steps="75"/></proof>
+  <proof prover="3"><result status="valid" time="0.024471" steps="73"/></proof>
   </goal>
   <goal name="get&#39;vc.13" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.033107" steps="75"/></proof>
+  <proof prover="3"><result status="valid" time="0.033107" steps="74"/></proof>
   </goal>
   <goal name="get&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.017460" steps="52"/></proof>
+  <proof prover="3"><result status="valid" time="0.017460" steps="52"/></proof>
   </goal>
   <goal name="get&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.026291" steps="77"/></proof>
+  <proof prover="3"><result status="valid" time="0.026291" steps="76"/></proof>
   </goal>
   <goal name="get&#39;vc.16" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.029452" steps="79"/></proof>
+  <proof prover="3"><result status="valid" time="0.029452" steps="78"/></proof>
   </goal>
   <goal name="get&#39;vc.17" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.045154" steps="81"/></proof>
+  <proof prover="3"><result status="valid" time="0.045154" steps="80"/></proof>
   </goal>
   <goal name="get&#39;vc.18" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.013955" steps="86"/></proof>
+  <proof prover="3"><result status="valid" time="0.013955" steps="85"/></proof>
   </goal>
   <goal name="get&#39;vc.19" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.057105" steps="222"/></proof>
+  <proof prover="3"><result status="valid" time="0.057105" steps="221"/></proof>
   </goal>
   <goal name="get&#39;vc.20" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.038290" steps="79"/></proof>
+  <proof prover="3"><result status="valid" time="0.038290" steps="78"/></proof>
   </goal>
   <goal name="get&#39;vc.21" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.036566" steps="60"/></proof>
+  <proof prover="3"><result status="valid" time="0.036566" steps="60"/></proof>
   </goal>
   <goal name="get&#39;vc.22" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.030365" steps="81"/></proof>
+  <proof prover="3"><result status="valid" time="0.030365" steps="81"/></proof>
   </goal>
   <goal name="get&#39;vc.23" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.029799" steps="57"/></proof>
+  <proof prover="3"><result status="valid" time="0.029799" steps="55"/></proof>
   </goal>
   <goal name="get&#39;vc.24" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.045509" steps="42"/></proof>
+  <proof prover="3"><result status="valid" time="0.045509" steps="42"/></proof>
   </goal>
   <goal name="get&#39;vc.25" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.283921" steps="22569"/></proof>
+  <proof prover="1"><result status="valid" time="0.080337" steps="22299"/></proof>
   </goal>
   <goal name="get&#39;vc.26" expl="postcondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.030945" steps="60"/></proof>
+  <proof prover="3"><result status="valid" time="0.030945" steps="58"/></proof>
   </goal>
  </transf>
  </goal>
@@ -347,183 +345,183 @@
  <goal name="resize&#39;vc" expl="VC for resize" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="resize&#39;vc.0" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.030380" steps="14"/></proof>
+  <proof prover="3"><result status="valid" time="0.030380" steps="14"/></proof>
   </goal>
   <goal name="resize&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.024363" steps="18"/></proof>
+  <proof prover="3"><result status="valid" time="0.024363" steps="18"/></proof>
   </goal>
   <goal name="resize&#39;vc.2" expl="integer overflow" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="25"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="24"/></proof>
   </goal>
   <goal name="resize&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="34"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="33"/></proof>
   </goal>
   <goal name="resize&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.030000" steps="106749"/></proof>
+  <proof prover="0"><result status="valid" time="0.030000" steps="105698"/></proof>
   </goal>
   <goal name="resize&#39;vc.5" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="49"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="48"/></proof>
   </goal>
   <goal name="resize&#39;vc.6" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="49"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="48"/></proof>
   </goal>
   <goal name="resize&#39;vc.7" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="28"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="28"/></proof>
   </goal>
   <goal name="resize&#39;vc.8" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="37"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="36"/></proof>
   </goal>
   <goal name="resize&#39;vc.9" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.110000" steps="17310"/></proof>
+  <proof prover="1"><result status="valid" time="0.110000" steps="17040"/></proof>
   </goal>
   <goal name="resize&#39;vc.10" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="51"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="50"/></proof>
   </goal>
   <goal name="resize&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.033517" steps="52"/></proof>
+  <proof prover="3"><result status="valid" time="0.033517" steps="51"/></proof>
   </goal>
   <goal name="resize&#39;vc.12" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="85"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="85"/></proof>
   </goal>
   <goal name="resize&#39;vc.13" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.047560" steps="81"/></proof>
+  <proof prover="3"><result status="valid" time="0.047560" steps="81"/></proof>
   </goal>
   <goal name="resize&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.044234" steps="83"/></proof>
+  <proof prover="3"><result status="valid" time="0.044234" steps="82"/></proof>
   </goal>
   <goal name="resize&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.053581" steps="101"/></proof>
+  <proof prover="3"><result status="valid" time="0.053581" steps="100"/></proof>
   </goal>
   <goal name="resize&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.051338" steps="103"/></proof>
+  <proof prover="3"><result status="valid" time="0.051338" steps="101"/></proof>
   </goal>
   <goal name="resize&#39;vc.17" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.054759" steps="110"/></proof>
+  <proof prover="3"><result status="valid" time="0.054759" steps="110"/></proof>
   </goal>
   <goal name="resize&#39;vc.18" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.050285" steps="113"/></proof>
+  <proof prover="3"><result status="valid" time="0.050285" steps="113"/></proof>
   </goal>
   <goal name="resize&#39;vc.19" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="82"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="82"/></proof>
   </goal>
   <goal name="resize&#39;vc.20" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="118"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="118"/></proof>
   </goal>
   <goal name="resize&#39;vc.21" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.020000" steps="120"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="120"/></proof>
   </goal>
   <goal name="resize&#39;vc.22" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.279674" steps="442938"/></proof>
+  <proof prover="0"><result status="valid" time="0.081917" steps="406207"/></proof>
   </goal>
   <goal name="resize&#39;vc.23" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.020000" steps="394"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="393"/></proof>
   </goal>
   <goal name="resize&#39;vc.24" expl="loop invariant init" proved="true">
-  <proof prover="6"><result status="valid" time="0.143185" steps="496"/></proof>
+  <proof prover="3"><result status="valid" time="0.143185" steps="494"/></proof>
   </goal>
   <goal name="resize&#39;vc.25" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.060589" steps="150"/></proof>
+  <proof prover="3"><result status="valid" time="0.060589" steps="149"/></proof>
   </goal>
   <goal name="resize&#39;vc.26" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.058543" steps="154"/></proof>
+  <proof prover="3"><result status="valid" time="0.058543" steps="153"/></proof>
   </goal>
   <goal name="resize&#39;vc.27" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.057361" steps="155"/></proof>
+  <proof prover="3"><result status="valid" time="0.057361" steps="155"/></proof>
   </goal>
   <goal name="resize&#39;vc.28" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.020000" steps="55149"/></proof>
+  <proof prover="0"><result status="valid" time="0.020000" steps="57397"/></proof>
   </goal>
   <goal name="resize&#39;vc.29" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.019989" steps="159"/></proof>
+  <proof prover="3"><result status="valid" time="0.019989" steps="159"/></proof>
   </goal>
   <goal name="resize&#39;vc.30" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.035052" steps="119"/></proof>
+  <proof prover="3"><result status="valid" time="0.035052" steps="119"/></proof>
   </goal>
   <goal name="resize&#39;vc.31" expl="precondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.041292" steps="119"/></proof>
+  <proof prover="3"><result status="valid" time="0.041292" steps="119"/></proof>
   </goal>
   <goal name="resize&#39;vc.32" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.059040" steps="159"/></proof>
+  <proof prover="3"><result status="valid" time="0.059040" steps="158"/></proof>
   </goal>
   <goal name="resize&#39;vc.33" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="124"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="124"/></proof>
   </goal>
   <goal name="resize&#39;vc.34" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.186472" steps="2091"/></proof>
+  <proof prover="3"><result status="valid" time="0.186472" steps="2089"/></proof>
   </goal>
   <goal name="resize&#39;vc.35" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.191667" steps="1995"/></proof>
+  <proof prover="3"><result status="valid" time="0.191667" steps="1994"/></proof>
   </goal>
   <goal name="resize&#39;vc.36" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.361865" steps="34980"/></proof>
+  <proof prover="1"><result status="valid" time="0.118505" steps="34501"/></proof>
   </goal>
   <goal name="resize&#39;vc.37" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.030000" steps="116959"/></proof>
+  <proof prover="0"><result status="valid" time="0.030000" steps="119892"/></proof>
   </goal>
   <goal name="resize&#39;vc.38" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.232864" steps="1933"/></proof>
+  <proof prover="3"><result status="valid" time="0.078660" steps="1933"/></proof>
   </goal>
   <goal name="resize&#39;vc.39" expl="unreachable point" proved="true">
-  <proof prover="6"><result status="valid" time="0.020000" steps="137"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="136"/></proof>
   </goal>
   <goal name="resize&#39;vc.40" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.046327" steps="86"/></proof>
+  <proof prover="3"><result status="valid" time="0.046327" steps="86"/></proof>
   </goal>
   <goal name="resize&#39;vc.41" expl="assertion" proved="true">
-  <proof prover="6"><result status="valid" time="0.366452" steps="5545"/></proof>
+  <proof prover="3"><result status="valid" time="0.146361" steps="5544"/></proof>
   </goal>
   <goal name="resize&#39;vc.42" expl="integer overflow" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="293"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="293"/></proof>
   </goal>
   <goal name="resize&#39;vc.43" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.020000" steps="159"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="158"/></proof>
   </goal>
   <goal name="resize&#39;vc.44" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.020000" steps="136"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="135"/></proof>
   </goal>
   <goal name="resize&#39;vc.45" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.020000" steps="310"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="310"/></proof>
   </goal>
   <goal name="resize&#39;vc.46" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="92"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="91"/></proof>
   </goal>
   <goal name="resize&#39;vc.47" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.020000" steps="32082"/></proof>
+  <proof prover="0"><result status="valid" time="0.020000" steps="33300"/></proof>
   </goal>
   <goal name="resize&#39;vc.48" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.020000" steps="143"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="143"/></proof>
   </goal>
   <goal name="resize&#39;vc.49" expl="loop invariant preservation" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="101"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="100"/></proof>
   </goal>
   <goal name="resize&#39;vc.50" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.031425" steps="69"/></proof>
+  <proof prover="3"><result status="valid" time="0.031425" steps="68"/></proof>
   </goal>
   <goal name="resize&#39;vc.51" expl="type invariant" proved="true">
-  <proof prover="6"><result status="valid" time="0.030989" steps="70"/></proof>
+  <proof prover="3"><result status="valid" time="0.030989" steps="70"/></proof>
   </goal>
   <goal name="resize&#39;vc.52" expl="postcondition" proved="true">
-  <proof prover="6"><result status="valid" time="0.010000" steps="76"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="75"/></proof>
   </goal>
   <goal name="resize&#39;vc.53" expl="postcondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.030000" steps="111080"/></proof>
+  <proof prover="0"><result status="valid" time="0.030000" steps="113438"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="Hashmap_Main" proved="true">
  <goal name="main&#39;vc" expl="VC for main" proved="true">
- <proof prover="0"><result status="valid" time="0.104287" steps="267775"/></proof>
+ <proof prover="0"><result status="valid" time="0.104287" steps="230311"/></proof>
  </goal>
 </theory>
 <theory name="Hashmap_Impl0" proved="true">
  <goal name="clone&#39;_refn" proved="true">
- <proof prover="6"><result status="valid" time="0.000000" steps="0"/></proof>
+ <proof prover="3"><result status="valid" time="0.000000" steps="0"/></proof>
  </goal>
 </theory>
 <theory name="Hashmap_Impl2" proved="true">
  <goal name="hash_refn" proved="true">
- <proof prover="6"><result status="valid" time="0.000000" steps="2"/></proof>
+ <proof prover="3"><result status="valid" time="0.000000" steps="2"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/hashmap/why3shapes.gz b/creusot/tests/should_succeed/hashmap/why3shapes.gz
index 21841afd8..06a7a43d5 100644
Binary files a/creusot/tests/should_succeed/hashmap/why3shapes.gz and b/creusot/tests/should_succeed/hashmap/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/heapsort_generic/why3session.xml b/creusot/tests/should_succeed/heapsort_generic/why3session.xml
index 6a7e391b4..4c89e63b4 100644
--- a/creusot/tests/should_succeed/heapsort_generic/why3session.xml
+++ b/creusot/tests/should_succeed/heapsort_generic/why3session.xml
@@ -2,204 +2,203 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="CVC4" version="1.8" timelimit="30" steplimit="0" memlimit="4000"/>
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="4" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="5" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="heapsort_generic.mlcfg"/>
 <theory name="HeapsortGeneric_HeapFragMax_Impl" proved="true">
  <goal name="heap_frag_max&#39;vc" expl="VC for heap_frag_max" proved="true">
- <proof prover="1"><result status="valid" time="0.050000" steps="514"/></proof>
+ <proof prover="5"><result status="valid" time="0.050000" steps="512"/></proof>
  </goal>
 </theory>
 <theory name="HeapsortGeneric_SiftDown" proved="true">
  <goal name="sift_down&#39;vc" expl="VC for sift_down" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="sift_down&#39;vc.0" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.019257" steps="17"/></proof>
+  <proof prover="5"><result status="valid" time="0.019257" steps="16"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.1" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="53"/></proof>
+  <proof prover="5"><result status="valid" time="0.010000" steps="53"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.2" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="20"/></proof>
+  <proof prover="5"><result status="valid" time="0.010000" steps="20"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.3" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="29"/></proof>
+  <proof prover="5"><result status="valid" time="0.010000" steps="29"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.020000" steps="66"/></proof>
+  <proof prover="5"><result status="valid" time="0.020000" steps="66"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.5" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="157291"/></proof>
+  <proof prover="2"><result status="valid" time="0.030000" steps="157388"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.6" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="279"/></proof>
+  <proof prover="5"><result status="valid" time="0.010000" steps="278"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.7" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="167648"/></proof>
+  <proof prover="2"><result status="valid" time="0.030000" steps="167703"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.8" expl="division by zero" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="35"/></proof>
+  <proof prover="5"><result status="valid" time="0.010000" steps="35"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.9" expl="division by zero" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="39"/></proof>
+  <proof prover="5"><result status="valid" time="0.010000" steps="39"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.10" expl="integer overflow" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="164775"/></proof>
+  <proof prover="2"><result status="valid" time="0.030000" steps="165052"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.11" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.035630" steps="97"/></proof>
+  <proof prover="5"><result status="valid" time="0.035630" steps="97"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.12" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.020000" steps="414"/></proof>
+  <proof prover="5"><result status="valid" time="0.020000" steps="412"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.13" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.020000" steps="445"/></proof>
+  <proof prover="5"><result status="valid" time="0.020000" steps="445"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.14" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="480"/></proof>
+  <proof prover="5"><result status="valid" time="0.010000" steps="479"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="173809"/></proof>
+  <proof prover="2"><result status="valid" time="0.030000" steps="173274"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.029478" steps="133"/></proof>
+  <proof prover="5"><result status="valid" time="0.029478" steps="132"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.17" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.032799" steps="134"/></proof>
+  <proof prover="5"><result status="valid" time="0.032799" steps="134"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.18" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.023321" steps="55"/></proof>
+  <proof prover="5"><result status="valid" time="0.023321" steps="55"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.19" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="139"/></proof>
+  <proof prover="5"><result status="valid" time="0.010000" steps="138"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.20" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="174905"/></proof>
+  <proof prover="2"><result status="valid" time="0.030000" steps="174323"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.21" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.038259" steps="150"/></proof>
+  <proof prover="5"><result status="valid" time="0.038259" steps="150"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.22" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.031945" steps="152"/></proof>
+  <proof prover="5"><result status="valid" time="0.031945" steps="150"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.23" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.029569" steps="63"/></proof>
+  <proof prover="5"><result status="valid" time="0.029569" steps="63"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.24" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.023018" steps="65"/></proof>
+  <proof prover="5"><result status="valid" time="0.023018" steps="65"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.25" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.016723" steps="65"/></proof>
+  <proof prover="5"><result status="valid" time="0.016723" steps="65"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.26" expl="integer overflow" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="175084"/></proof>
+  <proof prover="2"><result status="valid" time="0.030000" steps="175431"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.27" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.040000" steps="699"/></proof>
+  <proof prover="5"><result status="valid" time="0.040000" steps="698"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.28" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.017725" steps="176"/></proof>
+  <proof prover="5"><result status="valid" time="0.017725" steps="175"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.29" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.035307" steps="176"/></proof>
+  <proof prover="5"><result status="valid" time="0.035307" steps="176"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.30" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.065872" steps="55"/></proof>
+  <proof prover="5"><result status="valid" time="0.065872" steps="55"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.31" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="175863"/></proof>
+  <proof prover="2"><result status="valid" time="0.030000" steps="175281"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.32" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.029818" steps="182"/></proof>
+  <proof prover="5"><result status="valid" time="0.029818" steps="182"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.33" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.038886" steps="183"/></proof>
+  <proof prover="5"><result status="valid" time="0.038886" steps="183"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.34" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.036633" steps="59"/></proof>
+  <proof prover="5"><result status="valid" time="0.036633" steps="59"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.35" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.045196" steps="61"/></proof>
+  <proof prover="5"><result status="valid" time="0.045196" steps="61"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.36" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.046193" steps="61"/></proof>
+  <proof prover="5"><result status="valid" time="0.046193" steps="61"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.37" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.037116" steps="195"/></proof>
+  <proof prover="5"><result status="valid" time="0.037116" steps="195"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.38" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="184971"/></proof>
+  <proof prover="2"><result status="valid" time="0.030000" steps="183261"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.39" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.210581" steps="850966"/></proof>
+  <proof prover="2"><result status="valid" time="0.210581" steps="765294"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.40" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.021885" steps="212"/></proof>
+  <proof prover="5"><result status="valid" time="0.021885" steps="212"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.41" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.016507" steps="213"/></proof>
+  <proof prover="5"><result status="valid" time="0.016507" steps="212"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.42" expl="loop invariant preservation" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="193129"/></proof>
+  <proof prover="2"><result status="valid" time="0.030000" steps="191103"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.43" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.040000" steps="687"/></proof>
+  <proof prover="5"><result status="valid" time="0.040000" steps="686"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.44" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="0.320088" steps="47963"/></proof>
+  <proof prover="3"><result status="valid" time="0.184079" steps="47023"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.45" expl="loop invariant preservation" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="sift_down&#39;vc.45.0" expl="loop invariant preservation" proved="true">
    <transf name="split_vc" proved="true" >
     <goal name="sift_down&#39;vc.45.0.0" expl="loop invariant preservation" proved="true">
-    <proof prover="0"><result status="valid" time="2.676552" steps="317958"/></proof>
+    <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="1.790168" steps="316408"/></proof>
     </goal>
     <goal name="sift_down&#39;vc.45.0.1" expl="loop invariant preservation" proved="true">
-    <proof prover="0"><result status="valid" time="2.641470" steps="277660"/></proof>
+    <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="1.376872" steps="302348"/></proof>
     </goal>
    </transf>
    </goal>
    <goal name="sift_down&#39;vc.45.1" expl="loop invariant preservation" proved="true">
    <transf name="split_vc" proved="true" >
     <goal name="sift_down&#39;vc.45.1.0" expl="loop invariant preservation" proved="true">
-    <proof prover="0"><result status="valid" time="2.737553" steps="220726"/></proof>
+    <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="12.472128" steps="3131278"/></proof>
     </goal>
     <goal name="sift_down&#39;vc.45.1.1" expl="loop invariant preservation" proved="true">
-    <proof prover="0"><result status="valid" time="0.158569" steps="35009"/></proof>
+    <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="0.054973" steps="21892"/></proof>
     </goal>
    </transf>
    </goal>
   </transf>
   </goal>
   <goal name="sift_down&#39;vc.46" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="1.639577" steps="108166"/></proof>
+  <proof prover="3"><result status="valid" time="0.479836" steps="106812"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.47" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="1.414873" steps="83280"/></proof>
+  <proof prover="3"><result status="valid" time="0.394598" steps="82217"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.48" expl="loop invariant preservation" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="sift_down&#39;vc.48.0" expl="loop invariant preservation" proved="true">
-   <proof prover="3"><result status="valid" time="1.302965" steps="93179"/></proof>
+   <proof prover="3"><result status="valid" time="0.383628" steps="92085"/></proof>
    </goal>
    <goal name="sift_down&#39;vc.48.1" expl="loop invariant preservation" proved="true">
    <transf name="split_vc" proved="true" >
     <goal name="sift_down&#39;vc.48.1.0" expl="loop invariant preservation" proved="true">
-    <proof prover="3"><result status="valid" time="1.346498" steps="90877"/></proof>
+    <proof prover="3"><result status="valid" time="0.375629" steps="89708"/></proof>
     </goal>
     <goal name="sift_down&#39;vc.48.1.1" expl="loop invariant preservation" proved="true">
-    <proof prover="3"><result status="valid" time="0.207073" steps="23061"/></proof>
+    <proof prover="3"><result status="valid" time="0.055626" steps="22239"/></proof>
     </goal>
    </transf>
    </goal>
   </transf>
   </goal>
   <goal name="sift_down&#39;vc.49" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.023864" steps="188"/></proof>
+  <proof prover="5"><result status="valid" time="0.023864" steps="187"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.50" expl="postcondition" proved="true">
   <transf name="split_vc" proved="true" >
@@ -208,7 +207,7 @@
     <goal name="sift_down&#39;vc.50.0.0" expl="postcondition" proved="true">
     <transf name="split_vc" proved="true" >
      <goal name="sift_down&#39;vc.50.0.0.0" expl="postcondition" proved="true">
-     <proof prover="3"><result status="valid" time="0.745464" steps="62289"/></proof>
+     <proof prover="3"><result status="valid" time="0.227756" steps="60464"/></proof>
      </goal>
     </transf>
     </goal>
@@ -219,20 +218,20 @@
     <goal name="sift_down&#39;vc.50.1.0" expl="postcondition" proved="true">
     <transf name="split_vc" proved="true" >
      <goal name="sift_down&#39;vc.50.1.0.0" expl="postcondition" proved="true">
-     <proof prover="3"><result status="valid" time="0.851903" steps="107568"/></proof>
+     <proof prover="3"><result status="valid" time="0.349050" steps="98478"/></proof>
      </goal>
      <goal name="sift_down&#39;vc.50.1.0.1" expl="postcondition" proved="true">
-     <proof prover="3"><result status="valid" time="0.744415" steps="98842"/></proof>
+     <proof prover="3"><result status="valid" time="0.366909" steps="101467"/></proof>
      </goal>
     </transf>
     </goal>
     <goal name="sift_down&#39;vc.50.1.1" expl="postcondition" proved="true">
     <transf name="split_vc" proved="true" >
      <goal name="sift_down&#39;vc.50.1.1.0" expl="postcondition" proved="true">
-     <proof prover="3"><result status="valid" time="1.425595" steps="108307"/></proof>
+     <proof prover="3"><result status="valid" time="0.386946" steps="106769"/></proof>
      </goal>
      <goal name="sift_down&#39;vc.50.1.1.1" expl="postcondition" proved="true">
-     <proof prover="1"><result status="valid" time="0.037320" steps="53"/></proof>
+     <proof prover="5"><result status="valid" time="0.037320" steps="53"/></proof>
      </goal>
     </transf>
     </goal>
@@ -241,13 +240,13 @@
   </transf>
   </goal>
   <goal name="sift_down&#39;vc.51" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.143185" steps="352"/></proof>
+  <proof prover="5"><result status="valid" time="0.143185" steps="351"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.52" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.134008" steps="464"/></proof>
+  <proof prover="5"><result status="valid" time="0.134008" steps="464"/></proof>
   </goal>
   <goal name="sift_down&#39;vc.53" expl="postcondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.610787" steps="48366"/></proof>
+  <proof prover="3"><result status="valid" time="0.153040" steps="47381"/></proof>
   </goal>
  </transf>
  </goal>
@@ -256,115 +255,115 @@
  <goal name="heap_sort&#39;vc" expl="VC for heap_sort" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="heap_sort&#39;vc.0" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.026546" steps="19"/></proof>
+  <proof prover="5"><result status="valid" time="0.026546" steps="18"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.031402" steps="20"/></proof>
+  <proof prover="5"><result status="valid" time="0.031402" steps="20"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.2" expl="division by zero" proved="true">
-  <proof prover="1"><result status="valid" time="0.050000" steps="19"/></proof>
+  <proof prover="5"><result status="valid" time="0.050000" steps="19"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.3" expl="division by zero" proved="true">
-  <proof prover="1"><result status="valid" time="0.030000" steps="23"/></proof>
+  <proof prover="5"><result status="valid" time="0.030000" steps="23"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.4" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.070000" steps="74"/></proof>
+  <proof prover="5"><result status="valid" time="0.070000" steps="73"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.5" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.050000" steps="249"/></proof>
+  <proof prover="5"><result status="valid" time="0.050000" steps="249"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.6" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.180505" steps="621"/></proof>
+  <proof prover="5"><result status="valid" time="0.042698" steps="621"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.7" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.050000" steps="113"/></proof>
+  <proof prover="5"><result status="valid" time="0.050000" steps="113"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.8" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.050000" steps="126"/></proof>
+  <proof prover="5"><result status="valid" time="0.050000" steps="126"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.036609" steps="127"/></proof>
+  <proof prover="5"><result status="valid" time="0.036609" steps="126"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.020000" steps="153"/></proof>
+  <proof prover="5"><result status="valid" time="0.020000" steps="151"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.070000" steps="181"/></proof>
+  <proof prover="5"><result status="valid" time="0.070000" steps="181"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.12" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.030000" steps="159"/></proof>
+  <proof prover="5"><result status="valid" time="0.030000" steps="159"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.13" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.082669" steps="151"/></proof>
+  <proof prover="5"><result status="valid" time="0.082669" steps="150"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.14" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.369109" steps="1484"/></proof>
+  <proof prover="5"><result status="valid" time="0.091223" steps="1483"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.15" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.130000" steps="620"/></proof>
+  <proof prover="5"><result status="valid" time="0.130000" steps="619"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.16" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.160000" steps="788"/></proof>
+  <proof prover="5"><result status="valid" time="0.160000" steps="788"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.17" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.046440" steps="113"/></proof>
+  <proof prover="5"><result status="valid" time="0.046440" steps="113"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.18" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.070000" steps="133"/></proof>
+  <proof prover="5"><result status="valid" time="0.070000" steps="132"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.19" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="39"/></proof>
+  <proof prover="5"><result status="valid" time="0.010000" steps="39"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.20" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.040000" steps="157"/></proof>
+  <proof prover="5"><result status="valid" time="0.040000" steps="156"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.21" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.080000" steps="219"/></proof>
+  <proof prover="5"><result status="valid" time="0.080000" steps="219"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.22" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.060000" steps="145"/></proof>
+  <proof prover="5"><result status="valid" time="0.060000" steps="144"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.23" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.060000" steps="154"/></proof>
+  <proof prover="5"><result status="valid" time="0.060000" steps="153"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.24" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.041137" steps="152"/></proof>
+  <proof prover="5"><result status="valid" time="0.041137" steps="151"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.25" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.040000" steps="176"/></proof>
+  <proof prover="5"><result status="valid" time="0.040000" steps="175"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.26" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.060000" steps="176"/></proof>
+  <proof prover="5"><result status="valid" time="0.060000" steps="176"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.27" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.019194" steps="168"/></proof>
+  <proof prover="5"><result status="valid" time="0.019194" steps="167"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.28" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.036699" steps="169"/></proof>
+  <proof prover="5"><result status="valid" time="0.036699" steps="169"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.29" expl="assertion" proved="true">
-  <proof prover="0" timelimit="10"><result status="valid" time="1.452490" steps="247341"/></proof>
+  <proof prover="3" timelimit="10" memlimit="4000"><result status="valid" time="2.682752" steps="352760"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.30" expl="precondition" proved="true">
-  <proof prover="0" timelimit="5" memlimit="2000"><result status="valid" time="0.241869" steps="50817"/></proof>
+  <proof prover="3" timelimit="5" memlimit="2000"><result status="valid" time="0.241725" steps="73469"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.31" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.060000" steps="83"/></proof>
+  <proof prover="5"><result status="valid" time="0.060000" steps="83"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.32" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.090000" steps="193"/></proof>
+  <proof prover="5"><result status="valid" time="0.090000" steps="192"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.33" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.056983" steps="181"/></proof>
+  <proof prover="5"><result status="valid" time="0.056983" steps="181"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.34" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.160000" steps="755"/></proof>
+  <proof prover="5"><result status="valid" time="0.160000" steps="754"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.35" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.330244" steps="1678"/></proof>
+  <proof prover="5"><result status="valid" time="0.110403" steps="1677"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.36" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.110000" steps="197"/></proof>
+  <proof prover="5"><result status="valid" time="0.110000" steps="197"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.37" expl="loop invariant preservation" proved="true">
   <transf name="remove" proved="true" arg1="to_int_in_bounds,extensionality,zero_unsigned_is_zero,(==)&#39;spec,create&#39;spec,set&#39;spec,set&#39;def,([&lt;-])&#39;def,singleton&#39;spec,cons&#39;spec,snoc&#39;spec,([..])&#39;spec,([..])&#39;def,([_..])&#39;def,([.._])&#39;def,(++)&#39;spec,mem_append,mem_tail,occ_cons,occ_snoc,occ_tail,append_num_occ">
@@ -377,7 +376,7 @@
       <goal name="heap_sort&#39;vc.37.0.0.0.0" expl="loop invariant preservation" proved="true">
       <transf name="split_vc" proved="true" >
        <goal name="heap_sort&#39;vc.37.0.0.0.0.0" expl="loop invariant preservation" proved="true">
-       <proof prover="0"><result status="valid" time="2.308950" steps="363650"/></proof>
+       <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="26.554538" steps="6463459"/></proof>
        </goal>
       </transf>
       </goal>
@@ -390,16 +389,16 @@
   </transf>
   </goal>
   <goal name="heap_sort&#39;vc.38" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="0.620015" steps="68803"/></proof>
+  <proof prover="3"><result status="valid" time="0.211265" steps="63442"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.39" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.051245" steps="136"/></proof>
+  <proof prover="5"><result status="valid" time="0.051245" steps="136"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.40" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.180000" steps="1380"/></proof>
+  <proof prover="5"><result status="valid" time="0.180000" steps="1380"/></proof>
   </goal>
   <goal name="heap_sort&#39;vc.41" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.070000" steps="149"/></proof>
+  <proof prover="5"><result status="valid" time="0.070000" steps="148"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/heapsort_generic/why3shapes.gz b/creusot/tests/should_succeed/heapsort_generic/why3shapes.gz
index e697d1f0a..254a8e071 100644
Binary files a/creusot/tests/should_succeed/heapsort_generic/why3shapes.gz and b/creusot/tests/should_succeed/heapsort_generic/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/hillel/why3session.xml b/creusot/tests/should_succeed/hillel/why3session.xml
index 738919c0a..e09019425 100644
--- a/creusot/tests/should_succeed/hillel/why3session.xml
+++ b/creusot/tests/should_succeed/hillel/why3session.xml
@@ -3,11 +3,8 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="CVC4" version="1.8" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="3" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="4" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="5" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="4" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="hillel.mlcfg"/>
 <theory name="Hillel_RightPad" proved="true">
@@ -17,125 +14,125 @@
 </theory>
 <theory name="Hillel_LeftPad" proved="true">
  <goal name="left_pad&#39;vc" expl="VC for left_pad" proved="true">
- <proof prover="4"><result status="valid" time="0.471778" steps="3050"/></proof>
+ <proof prover="4"><result status="valid" time="0.182811" steps="3049"/></proof>
  </goal>
 </theory>
 <theory name="Hillel_SubsetPush_Impl" proved="true">
  <goal name="subset_push&#39;vc" expl="VC for subset_push" proved="true">
- <proof prover="4"><result status="valid" time="0.522172" steps="8068"/></proof>
+ <proof prover="4"><result status="valid" time="0.168500" steps="8068"/></proof>
  </goal>
 </theory>
 <theory name="Hillel_InsertUnique" proved="true">
  <goal name="insert_unique&#39;vc" expl="VC for insert_unique" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="insert_unique&#39;vc.0" expl="assertion" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="52"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="52"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.1" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.054720" steps="8890"/></proof>
+  <proof prover="0"><result status="valid" time="0.054720" steps="8738"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.017002" steps="22"/></proof>
+  <proof prover="4"><result status="valid" time="0.017002" steps="22"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.3" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.018021" steps="24"/></proof>
+  <proof prover="4"><result status="valid" time="0.018021" steps="24"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.010465" steps="26"/></proof>
+  <proof prover="4"><result status="valid" time="0.010465" steps="26"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.000000" steps="28"/></proof>
+  <proof prover="4"><result status="valid" time="0.000000" steps="28"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.020540" steps="30"/></proof>
+  <proof prover="4"><result status="valid" time="0.020540" steps="30"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.7" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.028132" steps="40"/></proof>
+  <proof prover="4"><result status="valid" time="0.028132" steps="40"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.8" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="42"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="42"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.9" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="78"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="78"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.10" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="50"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="50"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.11" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.016765" steps="60"/></proof>
+  <proof prover="4"><result status="valid" time="0.016765" steps="60"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.12" expl="assertion" proved="true">
-  <proof prover="5"><result status="valid" time="0.060000" steps="701"/></proof>
+  <proof prover="4"><result status="valid" time="0.060000" steps="700"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.13" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.019755" steps="74"/></proof>
+  <proof prover="4"><result status="valid" time="0.019755" steps="74"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="74"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="74"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.15" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.010016" steps="76"/></proof>
+  <proof prover="4"><result status="valid" time="0.010016" steps="76"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.16" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.016424" steps="60"/></proof>
+  <proof prover="4"><result status="valid" time="0.016424" steps="60"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.17" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.015252" steps="75"/></proof>
+  <proof prover="4"><result status="valid" time="0.015252" steps="75"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.18" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.024661" steps="81"/></proof>
+  <proof prover="4"><result status="valid" time="0.024661" steps="81"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.19" expl="assertion" proved="true">
-  <proof prover="5"><result status="valid" time="0.090000" steps="1574"/></proof>
+  <proof prover="4"><result status="valid" time="0.090000" steps="1574"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.20" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.021165" steps="89"/></proof>
+  <proof prover="4"><result status="valid" time="0.021165" steps="89"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.21" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.016713" steps="91"/></proof>
+  <proof prover="4"><result status="valid" time="0.016713" steps="91"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.22" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.024412" steps="91"/></proof>
+  <proof prover="4"><result status="valid" time="0.024412" steps="91"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.23" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.019742" steps="90"/></proof>
+  <proof prover="4"><result status="valid" time="0.019742" steps="90"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.24" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="99"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="99"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.25" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="678"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="677"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.26" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.129146" steps="804"/></proof>
+  <proof prover="4"><result status="valid" time="0.129146" steps="804"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.27" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.012497" steps="98"/></proof>
+  <proof prover="4"><result status="valid" time="0.012497" steps="98"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.28" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.012934" steps="100"/></proof>
+  <proof prover="4"><result status="valid" time="0.012934" steps="100"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.29" expl="assertion" proved="true">
-  <proof prover="5"><result status="valid" time="0.195951" steps="1392"/></proof>
+  <proof prover="4"><result status="valid" time="0.071216" steps="1391"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.30" expl="postcondition" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="insert_unique&#39;vc.30.0" expl="postcondition" proved="true">
-   <proof prover="5"><result status="valid" time="0.257975" steps="1958"/></proof>
+   <proof prover="4"><result status="valid" time="0.113604" steps="1958"/></proof>
    </goal>
    <goal name="insert_unique&#39;vc.30.1" expl="postcondition" proved="true">
-   <proof prover="5"><result status="valid" time="0.021706" steps="107"/></proof>
+   <proof prover="4"><result status="valid" time="0.021706" steps="107"/></proof>
    </goal>
   </transf>
   </goal>
   <goal name="insert_unique&#39;vc.31" expl="postcondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.400835" steps="702959"/></proof>
+  <proof prover="2"><result status="valid" time="0.400835" steps="1965011"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.32" expl="postcondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.982762" steps="91715"/></proof>
+  <proof prover="0"><result status="valid" time="0.370052" steps="90019"/></proof>
   </goal>
   <goal name="insert_unique&#39;vc.33" expl="postcondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.163990" steps="23331"/></proof>
+  <proof prover="0"><result status="valid" time="0.163990" steps="23073"/></proof>
   </goal>
  </transf>
  </goal>
@@ -144,7 +141,7 @@
  <goal name="unique&#39;vc" expl="VC for unique" proved="true">
  <transf name="remove" proved="true" arg1="zero,one,(-),(&gt;),(&lt;=),(&gt;=),abs,uint64&#39;maxInt,uint64&#39;minInt,max_uint64,length1,radix,min_unsigned,in_bounds,singleton,cons,snoc,(++),mAX&#39;,index_logic,is_inhabited,resolve2,new,Assoc1,Unit_def_l,Unit_def_r,Inv_def_l,Inv_def_r,Comm1,Assoc,Mul_distr_l,Mul_distr_r,Comm,Unitary,NonTrivialRing,Refl,Trans,Antisymm,Total,ZeroLessOne,CompatOrderAdd,CompatOrderMult,Abs_le,Abs_pos,Div_mod,Div_bound,Mod_bound,Div_sign_pos,Div_sign_neg,Mod_sign_pos,Mod_sign_neg,Rounds_toward_zero,Div_1,Mod_1,Div_inf,Mod_inf,Div_mult,Mod_mult,to_int_in_bounds,extensionality,zero_unsigned_is_zero,length_nonnegative,set&#39;spec,set&#39;def,([&lt;-])&#39;def,singleton&#39;spec,cons&#39;spec,([_..])&#39;def,([.._])&#39;def,(++)&#39;spec,new&#39;spec,slice&#39;invariant,shallow_model_spec,produces_trans_spec,produces_refl_spec,is_inhabited_spec">
   <goal name="unique&#39;vc.0" expl="VC for unique" proved="true">
-  <proof prover="4"><result status="valid" time="0.324821" steps="4542"/></proof>
+  <proof prover="4"><result status="valid" time="0.324821" steps="4003"/></proof>
   </goal>
  </transf>
  </goal>
@@ -156,12 +153,12 @@
 </theory>
 <theory name="Hillel_SumRangeSplit_Impl" proved="true">
  <goal name="sum_range_split&#39;vc" expl="VC for sum_range_split" proved="true">
- <proof prover="4"><result status="valid" time="0.010000" steps="99"/></proof>
+ <proof prover="4"><result status="valid" time="0.010000" steps="133"/></proof>
  </goal>
 </theory>
 <theory name="Hillel_Score_Impl" proved="true">
  <goal name="score&#39;vc" expl="VC for score" proved="true">
- <proof prover="0"><result status="valid" time="0.080000" steps="9062"/></proof>
+ <proof prover="0"><result status="valid" time="0.080000" steps="8464"/></proof>
  </goal>
 </theory>
 <theory name="Hillel_Fulcrum" proved="true">
@@ -171,113 +168,113 @@
   <proof prover="4"><result status="valid" time="0.010000" steps="12"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.015936" steps="26"/></proof>
+  <proof prover="4"><result status="valid" time="0.015936" steps="24"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.2" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="29"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="28"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.3" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="115"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="114"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="105"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="104"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.5" expl="loop invariant init" proved="true">
   <proof prover="4"><result status="valid" time="0.010000" steps="52"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.6" expl="assertion" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="707"/></proof>
+  <proof prover="4"><result status="valid" time="0.030000" steps="706"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.101620" steps="90418"/></proof>
+  <proof prover="2"><result status="valid" time="0.101620" steps="91350"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.8" expl="precondition" proved="true">
   <proof prover="4"><result status="valid" time="0.010000" steps="50"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.020505" steps="77"/></proof>
+  <proof prover="4"><result status="valid" time="0.020505" steps="76"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.10" expl="loop invariant init" proved="true">
   <proof prover="4"><result status="valid" time="0.010000" steps="58"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.11" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="94"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="92"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.12" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="217"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="216"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.13" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="107"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="106"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.14" expl="loop invariant init" proved="true">
   <proof prover="4"><result status="valid" time="0.010000" steps="121"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.15" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="130"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="129"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.16" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="155"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="154"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.17" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.023869" steps="126"/></proof>
+  <proof prover="4"><result status="valid" time="0.023869" steps="125"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.18" expl="postcondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.020000" steps="130"/></proof>
+  <proof prover="4"><result status="valid" time="0.020000" steps="129"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.19" expl="postcondition" proved="true">
   <proof prover="4"><result status="valid" time="0.050000" steps="655"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.20" expl="integer overflow" proved="true">
-  <proof prover="4"><result status="valid" time="0.020000" steps="165"/></proof>
+  <proof prover="4"><result status="valid" time="0.020000" steps="163"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.21" expl="index in bounds" proved="true">
-  <proof prover="0"><result status="valid" time="0.190000" steps="28756"/></proof>
+  <proof prover="0"><result status="valid" time="0.190000" steps="27987"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.22" expl="precondition" proved="true">
   <proof prover="4"><result status="valid" time="0.020000" steps="92"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.23" expl="integer overflow" proved="true">
-  <proof prover="0"><result status="valid" time="0.758894" steps="52940"/></proof>
+  <proof prover="0"><result status="valid" time="0.226084" steps="52301"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.24" expl="loop invariant preservation" proved="true">
   <proof prover="4"><result status="valid" time="0.010000" steps="157"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.25" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.281010" steps="24451"/></proof>
+  <proof prover="0"><result status="valid" time="0.086815" steps="23977"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.26" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="1.124092" steps="1418460"/></proof>
+  <proof prover="2"><result status="valid" time="0.528004" steps="4284770"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.27" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="1.129659" steps="73897"/></proof>
+  <proof prover="0"><result status="valid" time="0.289173" steps="70588"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.28" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.347044" steps="31171"/></proof>
+  <proof prover="0"><result status="valid" time="0.115980" steps="30708"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.29" expl="loop invariant preservation" proved="true">
-  <proof prover="3" timelimit="5"><result status="valid" time="1.195059" steps="1335559"/></proof>
+  <proof prover="2" timelimit="5"><result status="valid" time="0.250570" steps="1549241"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.30" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="1.271590" steps="62594"/></proof>
+  <proof prover="0"><result status="valid" time="0.429278" steps="62200"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.31" expl="integer overflow" proved="true">
-  <proof prover="0"><result status="valid" time="0.895146" steps="62598"/></proof>
+  <proof prover="0"><result status="valid" time="0.244683" steps="62175"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.32" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="0.047097" steps="89897"/></proof>
+  <proof prover="2"><result status="valid" time="0.047097" steps="92159"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.33" expl="loop invariant preservation" proved="true">
-  <proof prover="4"><result status="valid" time="0.348354" steps="1482"/></proof>
+  <proof prover="4"><result status="valid" time="0.077102" steps="1481"/></proof>
   </goal>
   <goal name="fulcrum&#39;vc.34" expl="loop invariant preservation" proved="true">
   <transf name="remove" proved="true" arg1="singleton,snoc">
    <goal name="fulcrum&#39;vc.34.0" expl="loop invariant preservation" proved="true">
-   <proof prover="1"><result status="valid" time="0.680576" steps="75388"/></proof>
+   <proof prover="0"><result status="valid" time="0.374168" steps="106861"/></proof>
    </goal>
   </transf>
   </goal>
   <goal name="fulcrum&#39;vc.35" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.200000" steps="22982"/></proof>
+  <proof prover="0"><result status="valid" time="0.079267" steps="22877"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/hillel/why3shapes.gz b/creusot/tests/should_succeed/hillel/why3shapes.gz
index c0716c812..abf3c6521 100644
Binary files a/creusot/tests/should_succeed/hillel/why3shapes.gz and b/creusot/tests/should_succeed/hillel/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/index_range/why3session.xml b/creusot/tests/should_succeed/index_range/why3session.xml
index ab65e191b..5fee4bbaa 100644
--- a/creusot/tests/should_succeed/index_range/why3session.xml
+++ b/creusot/tests/should_succeed/index_range/why3session.xml
@@ -2,198 +2,198 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="index_range.mlcfg"/>
 <theory name="IndexRange_CreateArr" proved="true">
  <goal name="create_arr&#39;vc" expl="VC for create_arr" proved="true">
- <proof prover="0"><result status="valid" time="0.452359" steps="719429"/></proof>
+ <proof prover="1"><result status="valid" time="0.180046" steps="706756"/></proof>
  </goal>
 </theory>
 <theory name="IndexRange_TestRange" proved="true">
  <goal name="test_range&#39;vc" expl="VC for test_range" proved="true">
- <proof prover="0"><result status="valid" time="1.330269" steps="1844048"/></proof>
+ <proof prover="1"><result status="valid" time="0.651296" steps="2379389"/></proof>
  </goal>
 </theory>
 <theory name="IndexRange_TestRangeTo" proved="true">
  <goal name="test_range_to&#39;vc" expl="VC for test_range_to" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="test_range_to&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.018601" steps="64"/></proof>
+  <proof prover="3"><result status="valid" time="0.018601" steps="64"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.018603" steps="36"/></proof>
+  <proof prover="3"><result status="valid" time="0.018603" steps="36"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009889" steps="37"/></proof>
+  <proof prover="3"><result status="valid" time="0.009889" steps="36"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.022309" steps="26"/></proof>
+  <proof prover="3"><result status="valid" time="0.022309" steps="24"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.4" expl="index in bounds" proved="true">
-  <proof prover="2"><result status="valid" time="0.023802" steps="128"/></proof>
+  <proof prover="3"><result status="valid" time="0.023802" steps="127"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.020791" steps="45"/></proof>
+  <proof prover="3"><result status="valid" time="0.020791" steps="43"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.6" expl="index in bounds" proved="true">
-  <proof prover="2"><result status="valid" time="0.038420" steps="190"/></proof>
+  <proof prover="3"><result status="valid" time="0.038420" steps="188"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.023533" steps="64"/></proof>
+  <proof prover="3"><result status="valid" time="0.023533" steps="63"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.039089" steps="219"/></proof>
+  <proof prover="3"><result status="valid" time="0.039089" steps="218"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.040842" steps="113"/></proof>
+  <proof prover="3"><result status="valid" time="0.040842" steps="113"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.041801" steps="114"/></proof>
+  <proof prover="3"><result status="valid" time="0.041801" steps="113"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.026291" steps="68"/></proof>
+  <proof prover="3"><result status="valid" time="0.026291" steps="67"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.12" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.039692" steps="127"/></proof>
+  <proof prover="3"><result status="valid" time="0.039692" steps="127"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.13" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.029806" steps="77"/></proof>
+  <proof prover="3"><result status="valid" time="0.029806" steps="77"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.030911" steps="141"/></proof>
+  <proof prover="3"><result status="valid" time="0.030911" steps="140"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.030856" steps="149"/></proof>
+  <proof prover="3"><result status="valid" time="0.030856" steps="148"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.041386" steps="383"/></proof>
+  <proof prover="3"><result status="valid" time="0.041386" steps="382"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.17" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.032972" steps="168"/></proof>
+  <proof prover="3"><result status="valid" time="0.032972" steps="167"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.18" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.033770" steps="169"/></proof>
+  <proof prover="3"><result status="valid" time="0.033770" steps="168"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.19" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.040729" steps="187"/></proof>
+  <proof prover="3"><result status="valid" time="0.040729" steps="187"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.20" expl="index in bounds" proved="true">
-  <proof prover="2"><result status="valid" time="0.085769" steps="586"/></proof>
+  <proof prover="3"><result status="valid" time="0.085769" steps="585"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.21" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.026927" steps="127"/></proof>
+  <proof prover="3"><result status="valid" time="0.026927" steps="126"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.22" expl="index in bounds" proved="true">
-  <proof prover="2"><result status="valid" time="0.095159" steps="807"/></proof>
+  <proof prover="3"><result status="valid" time="0.095159" steps="806"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.23" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.038629" steps="159"/></proof>
+  <proof prover="3"><result status="valid" time="0.038629" steps="158"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.24" expl="index in bounds" proved="true">
-  <proof prover="2"><result status="valid" time="0.028291" steps="182"/></proof>
+  <proof prover="3"><result status="valid" time="0.028291" steps="180"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.25" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.025856" steps="183"/></proof>
+  <proof prover="3"><result status="valid" time="0.025856" steps="183"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.26" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.044914" steps="355"/></proof>
+  <proof prover="3"><result status="valid" time="0.044914" steps="355"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.27" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.030057" steps="207"/></proof>
+  <proof prover="3"><result status="valid" time="0.030057" steps="207"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.28" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.046611" steps="396"/></proof>
+  <proof prover="3"><result status="valid" time="0.046611" steps="396"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.29" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.054579" steps="398"/></proof>
+  <proof prover="3"><result status="valid" time="0.054579" steps="398"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.30" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.029811" steps="211"/></proof>
+  <proof prover="3"><result status="valid" time="0.029811" steps="209"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.31" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.055926" steps="405"/></proof>
+  <proof prover="3"><result status="valid" time="0.055926" steps="403"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.32" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.053796" steps="405"/></proof>
+  <proof prover="3"><result status="valid" time="0.053796" steps="405"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.33" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.036415" steps="215"/></proof>
+  <proof prover="3"><result status="valid" time="0.036415" steps="214"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.34" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.080859" steps="413"/></proof>
+  <proof prover="3"><result status="valid" time="0.080859" steps="411"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.35" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.073584" steps="414"/></proof>
+  <proof prover="3"><result status="valid" time="0.073584" steps="413"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.36" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.053095" steps="219"/></proof>
+  <proof prover="3"><result status="valid" time="0.053095" steps="218"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.37" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.063416" steps="421"/></proof>
+  <proof prover="3"><result status="valid" time="0.063416" steps="420"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.38" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.056447" steps="422"/></proof>
+  <proof prover="3"><result status="valid" time="0.056447" steps="422"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.39" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.034534" steps="227"/></proof>
+  <proof prover="3"><result status="valid" time="0.034534" steps="226"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.40" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.058163" steps="438"/></proof>
+  <proof prover="3"><result status="valid" time="0.058163" steps="438"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.41" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.064435" steps="457"/></proof>
+  <proof prover="3"><result status="valid" time="0.064435" steps="456"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.42" expl="VC for test_range_to" proved="true">
-  <proof prover="2"><result status="valid" time="0.126453" steps="983"/></proof>
+  <proof prover="3"><result status="valid" time="0.126453" steps="981"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.43" expl="unreachable point" proved="true">
-  <proof prover="2"><result status="valid" time="0.122547" steps="943"/></proof>
+  <proof prover="3"><result status="valid" time="0.122547" steps="943"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.44" expl="unreachable point" proved="true">
-  <proof prover="2"><result status="valid" time="0.281613" steps="1771"/></proof>
+  <proof prover="3"><result status="valid" time="0.088526" steps="1771"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.45" expl="unreachable point" proved="true">
-  <proof prover="2"><result status="valid" time="0.329153" steps="1824"/></proof>
+  <proof prover="3"><result status="valid" time="0.091019" steps="1824"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.46" expl="unreachable point" proved="true">
-  <proof prover="2"><result status="valid" time="0.279957" steps="1577"/></proof>
+  <proof prover="3"><result status="valid" time="0.079843" steps="1576"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.47" expl="unreachable point" proved="true">
-  <proof prover="2"><result status="valid" time="0.056898" steps="399"/></proof>
+  <proof prover="3"><result status="valid" time="0.056898" steps="399"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.48" expl="unreachable point" proved="true">
-  <proof prover="2"><result status="valid" time="0.263709" steps="1458"/></proof>
+  <proof prover="3"><result status="valid" time="0.073526" steps="1458"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.49" expl="unreachable point" proved="true">
-  <proof prover="2"><result status="valid" time="0.088143" steps="650"/></proof>
+  <proof prover="3"><result status="valid" time="0.088143" steps="649"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.50" expl="unreachable point" proved="true">
-  <proof prover="2"><result status="valid" time="0.080546" steps="307"/></proof>
+  <proof prover="3"><result status="valid" time="0.080546" steps="307"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.51" expl="unreachable point" proved="true">
-  <proof prover="2"><result status="valid" time="0.055844" steps="312"/></proof>
+  <proof prover="3"><result status="valid" time="0.055844" steps="311"/></proof>
   </goal>
   <goal name="test_range_to&#39;vc.52" expl="unreachable point" proved="true">
-  <proof prover="2"><result status="valid" time="0.052196" steps="433"/></proof>
+  <proof prover="3"><result status="valid" time="0.052196" steps="432"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="IndexRange_TestRangeFrom" proved="true">
  <goal name="test_range_from&#39;vc" expl="VC for test_range_from" proved="true">
- <proof prover="0"><result status="valid" time="1.188261" steps="1442130"/></proof>
+ <proof prover="1"><result status="valid" time="0.360073" steps="1490134"/></proof>
  </goal>
 </theory>
 <theory name="IndexRange_TestRangeFull" proved="true">
  <goal name="test_range_full&#39;vc" expl="VC for test_range_full" proved="true">
- <proof prover="0"><result status="valid" time="0.170811" steps="182416"/></proof>
+ <proof prover="1"><result status="valid" time="0.039072" steps="181703"/></proof>
  </goal>
 </theory>
 <theory name="IndexRange_TestRangeToInclusive" proved="true">
  <goal name="test_range_to_inclusive&#39;vc" expl="VC for test_range_to_inclusive" proved="true">
- <proof prover="0"><result status="valid" time="1.100005" steps="1555728"/></proof>
+ <proof prover="1"><result status="valid" time="0.277268" steps="1243989"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/index_range/why3shapes.gz b/creusot/tests/should_succeed/index_range/why3shapes.gz
index 4bac77746..832f93d12 100644
Binary files a/creusot/tests/should_succeed/index_range/why3shapes.gz and b/creusot/tests/should_succeed/index_range/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/inplace_list_reversal/why3session.xml b/creusot/tests/should_succeed/inplace_list_reversal/why3session.xml
index 9b15505cd..71aca0aaf 100644
--- a/creusot/tests/should_succeed/inplace_list_reversal/why3session.xml
+++ b/creusot/tests/should_succeed/inplace_list_reversal/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="inplace_list_reversal.mlcfg"/>
 <theory name="InplaceListReversal_Rev" proved="true">
  <goal name="rev&#39;vc" expl="VC for rev" proved="true">
- <proof prover="1"><result status="valid" time="0.020000" steps="133"/></proof>
+ <proof prover="0"><result status="valid" time="0.020000" steps="131"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/ite_normalize/why3session.xml b/creusot/tests/should_succeed/ite_normalize/why3session.xml
index d9463c87a..9f8f80153 100644
--- a/creusot/tests/should_succeed/ite_normalize/why3session.xml
+++ b/creusot/tests/should_succeed/ite_normalize/why3session.xml
@@ -2,7 +2,7 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="2" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
@@ -19,7 +19,7 @@
 </theory>
 <theory name="IteNormalize_Impl5_Transpose" proved="true">
  <goal name="transpose&#39;vc" expl="VC for transpose" proved="true">
- <proof prover="1"><result status="valid" time="0.013559" steps="11300"/></proof>
+ <proof prover="0"><result status="valid" time="0.013467" steps="8944"/></proof>
  </goal>
 </theory>
 <theory name="IteNormalize_Impl5_Normalize" proved="true">
@@ -44,7 +44,7 @@
 </theory>
 <theory name="IteNormalize_Impl6" proved="true">
  <goal name="clone&#39;_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.008889" steps="2998"/></proof>
+ <proof prover="0"><result status="valid" time="0.012259" steps="2839"/></proof>
  </goal>
 </theory>
 <theory name="IteNormalize_Impl3" proved="true">
diff --git a/creusot/tests/should_succeed/iterators/01_range/why3session.xml b/creusot/tests/should_succeed/iterators/01_range/why3session.xml
index 2e3e237a6..cd5427ea3 100644
--- a/creusot/tests/should_succeed/iterators/01_range/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/01_range/why3session.xml
@@ -2,43 +2,43 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="01_range.mlcfg"/>
 <theory name="C01Range_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="1"><result status="valid" time="0.030655" steps="13"/></proof>
+ <proof prover="0"><result status="valid" time="0.030655" steps="13"/></proof>
  </goal>
 </theory>
 <theory name="C01Range_Impl0_ProducesTrans_Impl" proved="true">
  <goal name="produces_trans&#39;vc" expl="VC for produces_trans" proved="true">
- <proof prover="1"><result status="valid" time="0.077811" steps="289"/></proof>
+ <proof prover="0"><result status="valid" time="0.077811" steps="288"/></proof>
  </goal>
 </theory>
 <theory name="C01Range_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
- <proof prover="1"><result status="valid" time="0.065018" steps="268"/></proof>
+ <proof prover="0"><result status="valid" time="0.065018" steps="268"/></proof>
  </goal>
 </theory>
 <theory name="C01Range_Impl1_IntoIter" proved="true">
  <goal name="into_iter&#39;vc" expl="VC for into_iter" proved="true">
- <proof prover="1"><result status="valid" time="0.013305" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.013305" steps="0"/></proof>
  </goal>
 </theory>
 <theory name="C01Range_SumRange" proved="true">
  <goal name="sum_range&#39;vc" expl="VC for sum_range" proved="true">
- <proof prover="1"><result status="valid" time="0.130000" steps="1745"/></proof>
+ <proof prover="0"><result status="valid" time="0.130000" steps="1739"/></proof>
  </goal>
 </theory>
 <theory name="C01Range_Impl0" proved="true">
  <goal name="produces_refl_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.016725" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.016725" steps="0"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.013647" steps="14"/></proof>
+ <proof prover="0"><result status="valid" time="0.013647" steps="14"/></proof>
  </goal>
  <goal name="next_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.013215" steps="112"/></proof>
+ <proof prover="0"><result status="valid" time="0.013215" steps="112"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/01_range/why3shapes.gz b/creusot/tests/should_succeed/iterators/01_range/why3shapes.gz
index 9e56edc7f..f906967c8 100644
Binary files a/creusot/tests/should_succeed/iterators/01_range/why3shapes.gz and b/creusot/tests/should_succeed/iterators/01_range/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/02_iter_mut/why3session.xml b/creusot/tests/should_succeed/iterators/02_iter_mut/why3session.xml
index 8da874725..ab02f40f5 100644
--- a/creusot/tests/should_succeed/iterators/02_iter_mut/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/02_iter_mut/why3session.xml
@@ -2,100 +2,100 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="4" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="02_iter_mut.mlcfg"/>
 <theory name="C02IterMut_Impl1_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="74"/></proof>
+ <proof prover="4"><result status="valid" time="0.010000" steps="74"/></proof>
  </goal>
 </theory>
 <theory name="C02IterMut_Impl1_ProducesTrans_Impl" proved="true">
  <goal name="produces_trans&#39;vc" expl="VC for produces_trans" proved="true">
- <proof prover="1"><result status="valid" time="0.050000" steps="672"/></proof>
+ <proof prover="4"><result status="valid" time="0.050000" steps="671"/></proof>
  </goal>
 </theory>
 <theory name="C02IterMut_Impl1_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="next&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.038350" steps="19"/></proof>
+  <proof prover="4"><result status="valid" time="0.038350" steps="19"/></proof>
   </goal>
   <goal name="next&#39;vc.1" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.123258" steps="18761"/></proof>
+  <proof prover="3"><result status="valid" time="0.123258" steps="18585"/></proof>
   </goal>
   <goal name="next&#39;vc.2" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.430760" steps="5839"/></proof>
+  <proof prover="4"><result status="valid" time="0.430760" steps="5876"/></proof>
   </goal>
   <goal name="next&#39;vc.3" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.012472" steps="21"/></proof>
+  <proof prover="4"><result status="valid" time="0.012472" steps="21"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="C02IterMut_Impl2_IntoIter" proved="true">
  <goal name="into_iter&#39;vc" expl="VC for into_iter" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="6"/></proof>
+ <proof prover="4"><result status="valid" time="0.000000" steps="6"/></proof>
  </goal>
 </theory>
 <theory name="C02IterMut_IterMut" proved="true">
  <goal name="iter_mut&#39;vc" expl="VC for iter_mut" proved="true">
- <proof prover="2"><result status="valid" time="0.046575" steps="107733"/></proof>
+ <proof prover="0"><result status="valid" time="0.046575" steps="99541"/></proof>
  </goal>
 </theory>
 <theory name="C02IterMut_AllZero" proved="true">
  <goal name="all_zero&#39;vc" expl="VC for all_zero" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="all_zero&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010840" steps="11"/></proof>
+  <proof prover="4"><result status="valid" time="0.010840" steps="11"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.024291" steps="14"/></proof>
+  <proof prover="4"><result status="valid" time="0.024291" steps="14"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.2" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="20"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="20"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.3" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="35"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="35"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="42"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="42"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="42"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="42"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.6" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="53"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="53"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.7" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.099677" steps="895"/></proof>
+  <proof prover="4"><result status="valid" time="0.099677" steps="880"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.8" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="54"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="54"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.9" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.041605" steps="701"/></proof>
+  <proof prover="4"><result status="valid" time="0.041605" steps="711"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.10" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.150551" steps="875"/></proof>
+  <proof prover="4"><result status="valid" time="0.150551" steps="873"/></proof>
   </goal>
   <goal name="all_zero&#39;vc.11" expl="unreachable point" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="53"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="53"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="C02IterMut_Impl1" proved="true">
  <goal name="produces_refl_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="3"/></proof>
+ <proof prover="4"><result status="valid" time="0.010000" steps="2"/></proof>
  </goal>
  <goal name="next_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.020000" steps="3"/></proof>
+ <proof prover="4"><result status="valid" time="0.020000" steps="2"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="3"/></proof>
+ <proof prover="4"><result status="valid" time="0.010000" steps="2"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/02_iter_mut/why3shapes.gz b/creusot/tests/should_succeed/iterators/02_iter_mut/why3shapes.gz
index 58d6bdfa4..0d75a0266 100644
Binary files a/creusot/tests/should_succeed/iterators/02_iter_mut/why3shapes.gz and b/creusot/tests/should_succeed/iterators/02_iter_mut/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/03_std_iterators/why3session.xml b/creusot/tests/should_succeed/iterators/03_std_iterators/why3session.xml
index e9654e3b1..9abeace1f 100644
--- a/creusot/tests/should_succeed/iterators/03_std_iterators/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/03_std_iterators/why3session.xml
@@ -2,186 +2,186 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="2" name="CVC4" version="1.8" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="3" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<file format="mlcfg" proved="true">
+<prover id="4" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
+<file format="mlcfg">
 <path name=".."/><path name="03_std_iterators.mlcfg"/>
 <theory name="C03StdIterators_SliceIter" proved="true">
  <goal name="slice_iter&#39;vc" expl="VC for slice_iter" proved="true">
- <proof prover="0"><result status="valid" time="0.158075" steps="1313"/></proof>
+ <proof prover="4"><result status="valid" time="0.158075" steps="1313"/></proof>
  </goal>
 </theory>
 <theory name="C03StdIterators_VecIter" proved="true">
  <goal name="vec_iter&#39;vc" expl="VC for vec_iter" proved="true">
- <proof prover="0"><result status="valid" time="0.215396" steps="1232"/></proof>
+ <proof prover="4"><result status="valid" time="0.065009" steps="1232"/></proof>
  </goal>
 </theory>
 <theory name="C03StdIterators_AllZero" proved="true">
  <goal name="all_zero&#39;vc" expl="VC for all_zero" proved="true">
- <proof prover="0"><result status="valid" time="0.215967" steps="2008"/></proof>
+ <proof prover="4"><result status="valid" time="0.215967" steps="1991"/></proof>
  </goal>
 </theory>
 <theory name="C03StdIterators_SkipTake" proved="true">
  <goal name="skip_take&#39;vc" expl="VC for skip_take" proved="true">
- <proof prover="0"><result status="valid" time="0.020000" steps="240"/></proof>
+ <proof prover="4"><result status="valid" time="0.020000" steps="240"/></proof>
  </goal>
 </theory>
 <theory name="C03StdIterators_Counter_Closure0" proved="true">
  <goal name="c03StdIterators_Counter_Closure0&#39;vc" expl="VC for c03StdIterators_Counter_Closure0" proved="true">
- <proof prover="0"><result status="valid" time="0.020000" steps="126"/></proof>
+ <proof prover="4"><result status="valid" time="0.020000" steps="126"/></proof>
  </goal>
 </theory>
 <theory name="C03StdIterators_Counter" proved="true">
  <goal name="counter&#39;vc" expl="VC for counter" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="counter&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.010000" steps="12"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="12"/></proof>
   </goal>
   <goal name="counter&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.028332" steps="12"/></proof>
+  <proof prover="4"><result status="valid" time="0.028332" steps="12"/></proof>
   </goal>
   <goal name="counter&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.010000" steps="89"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="89"/></proof>
   </goal>
   <goal name="counter&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.059895" steps="193434"/></proof>
+  <proof prover="1"><result status="valid" time="0.059895" steps="183671"/></proof>
   </goal>
   <goal name="counter&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.020000" steps="302"/></proof>
+  <proof prover="4"><result status="valid" time="0.020000" steps="304"/></proof>
   </goal>
   <goal name="counter&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.056748" steps="110885"/></proof>
+  <proof prover="1"><result status="valid" time="0.056748" steps="112192"/></proof>
   </goal>
   <goal name="counter&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.024487" steps="26"/></proof>
+  <proof prover="4"><result status="valid" time="0.024487" steps="26"/></proof>
   </goal>
   <goal name="counter&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.025325" steps="22"/></proof>
+  <proof prover="4"><result status="valid" time="0.025325" steps="22"/></proof>
   </goal>
   <goal name="counter&#39;vc.8" expl="assertion" proved="true">
-  <proof prover="0"><result status="valid" time="0.234495" steps="618"/></proof>
+  <proof prover="4"><result status="valid" time="0.234495" steps="617"/></proof>
   </goal>
   <goal name="counter&#39;vc.9" expl="assertion" proved="true">
-  <proof prover="3"><result status="valid" time="0.050000" steps="271726"/></proof>
+  <proof prover="1"><result status="valid" time="0.050000" steps="284065"/></proof>
   </goal>
   <goal name="counter&#39;vc.10" expl="assertion" proved="true">
-  <proof prover="3"><result status="valid" time="0.118193" steps="414854"/></proof>
+  <proof prover="1"><result status="valid" time="0.118193" steps="406973"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="C03StdIterators_SumRange" proved="true">
  <goal name="sum_range&#39;vc" expl="VC for sum_range" proved="true">
- <proof prover="0"><result status="valid" time="0.383139" steps="1656"/></proof>
+ <proof prover="4"><result status="valid" time="0.088610" steps="1654"/></proof>
  </goal>
 </theory>
 <theory name="C03StdIterators_EnumerateRange" proved="true">
  <goal name="enumerate_range&#39;vc" expl="VC for enumerate_range" proved="true">
- <proof prover="0"><result status="valid" time="0.236249" steps="2261"/></proof>
+ <proof prover="4"><result status="valid" time="0.236249" steps="2260"/></proof>
  </goal>
 </theory>
-<theory name="C03StdIterators_MyReverse" proved="true">
- <goal name="my_reverse&#39;vc" expl="VC for my_reverse" proved="true">
- <transf name="split_vc" proved="true" >
-  <goal name="my_reverse&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.067079" steps="19437"/></proof>
+<theory name="C03StdIterators_MyReverse">
+ <goal name="my_reverse&#39;vc" expl="VC for my_reverse">
+ <transf name="split_vc" >
+  <goal name="my_reverse&#39;vc.0" expl="precondition">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.067079" steps="19437"/></proof>
   </goal>
   <goal name="my_reverse&#39;vc.1" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.016334" steps="14"/></proof>
+  <proof prover="4"><result status="valid" time="0.016334" steps="13"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.2" expl="division by zero" proved="true">
-  <proof prover="2"><result status="valid" time="0.059613" steps="26526"/></proof>
+  <goal name="my_reverse&#39;vc.2" expl="division by zero">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.059613" steps="26526"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.3" expl="division by zero" proved="true">
-  <proof prover="2"><result status="valid" time="0.042711" steps="26233"/></proof>
+  <goal name="my_reverse&#39;vc.3" expl="division by zero">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.042711" steps="26233"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.4" expl="division by zero" proved="true">
-  <proof prover="2"><result status="valid" time="0.043480" steps="26244"/></proof>
+  <goal name="my_reverse&#39;vc.4" expl="division by zero">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.043480" steps="26244"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.5" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.067909" steps="30060"/></proof>
+  <goal name="my_reverse&#39;vc.5" expl="integer overflow">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.067909" steps="30060"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.6" expl="division by zero" proved="true">
-  <proof prover="2"><result status="valid" time="0.045045" steps="27890"/></proof>
+  <goal name="my_reverse&#39;vc.6" expl="division by zero">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.045045" steps="27890"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.7" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.056021" steps="28281"/></proof>
+  <goal name="my_reverse&#39;vc.7" expl="integer overflow">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.056021" steps="28281"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.041619" steps="27909"/></proof>
+  <goal name="my_reverse&#39;vc.8" expl="precondition">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.041619" steps="27909"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.082838" steps="28590"/></proof>
+  <goal name="my_reverse&#39;vc.9" expl="precondition">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.082838" steps="28590"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.064227" steps="28606"/></proof>
+  <goal name="my_reverse&#39;vc.10" expl="precondition">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.064227" steps="28606"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.067717" steps="28242"/></proof>
+  <goal name="my_reverse&#39;vc.11" expl="precondition">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.067717" steps="28242"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.12" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.116451" steps="28245"/></proof>
+  <goal name="my_reverse&#39;vc.12" expl="precondition">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.116451" steps="28245"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.13" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.047024" steps="29036"/></proof>
+  <goal name="my_reverse&#39;vc.13" expl="loop invariant init">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.047024" steps="29036"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.14" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.062704" steps="29099"/></proof>
+  <goal name="my_reverse&#39;vc.14" expl="loop invariant init">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.062704" steps="29099"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.15" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.059406" steps="29239"/></proof>
+  <goal name="my_reverse&#39;vc.15" expl="loop invariant init">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.059406" steps="29239"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.16" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.101071" steps="38856"/></proof>
+  <goal name="my_reverse&#39;vc.16" expl="loop invariant init">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.101071" steps="38856"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.17" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.210750" steps="39303"/></proof>
+  <goal name="my_reverse&#39;vc.17" expl="loop invariant init">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.210750" steps="39303"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.18" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.128860" steps="39578"/></proof>
+  <goal name="my_reverse&#39;vc.18" expl="loop invariant init">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.128860" steps="39578"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.19" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.232471" steps="36567"/></proof>
+  <goal name="my_reverse&#39;vc.19" expl="precondition">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.232471" steps="36567"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.20" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.237774" steps="38228"/></proof>
+  <goal name="my_reverse&#39;vc.20" expl="type invariant">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.237774" steps="38228"/></proof>
   </goal>
   <goal name="my_reverse&#39;vc.21" expl="postcondition" proved="true">
-  <proof prover="0" timelimit="5" memlimit="2000"><result status="valid" time="1.714636" steps="10396"/></proof>
+  <proof prover="4" timelimit="5" memlimit="2000"><result status="valid" time="0.486385" steps="10396"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.22" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.610429" steps="70898"/></proof>
+  <goal name="my_reverse&#39;vc.22" expl="integer overflow">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.610429" steps="70898"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.23" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.514444" steps="70879"/></proof>
+  <goal name="my_reverse&#39;vc.23" expl="integer overflow">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.514444" steps="70879"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.24" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.594327" steps="73015"/></proof>
+  <goal name="my_reverse&#39;vc.24" expl="precondition">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.594327" steps="73015"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.25" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.296823" steps="43971"/></proof>
+  <goal name="my_reverse&#39;vc.25" expl="precondition">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.296823" steps="43971"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.26" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.255419" steps="40055"/></proof>
+  <goal name="my_reverse&#39;vc.26" expl="precondition">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.255419" steps="40055"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.27" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.246796" steps="40080"/></proof>
+  <goal name="my_reverse&#39;vc.27" expl="loop invariant preservation">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.246796" steps="40080"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.28" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.342139" steps="49704"/></proof>
+  <goal name="my_reverse&#39;vc.28" expl="loop invariant preservation">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.342139" steps="49704"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.29" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.356173" steps="44657"/></proof>
+  <goal name="my_reverse&#39;vc.29" expl="loop invariant preservation">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.356173" steps="44657"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.30" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.654114" steps="91124"/></proof>
+  <goal name="my_reverse&#39;vc.30" expl="loop invariant preservation">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.654114" steps="91124"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.31" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="1.770357" steps="398532"/></proof>
+  <goal name="my_reverse&#39;vc.31" expl="loop invariant preservation">
+  <proof prover="2" obsolete="true"><result status="valid" time="1.770357" steps="398532"/></proof>
   </goal>
-  <goal name="my_reverse&#39;vc.32" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.968666" steps="150354"/></proof>
+  <goal name="my_reverse&#39;vc.32" expl="loop invariant preservation">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.968666" steps="150354"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/iterators/03_std_iterators/why3shapes.gz b/creusot/tests/should_succeed/iterators/03_std_iterators/why3shapes.gz
index 8aabb4955..b3b40f4a7 100644
Binary files a/creusot/tests/should_succeed/iterators/03_std_iterators/why3shapes.gz and b/creusot/tests/should_succeed/iterators/03_std_iterators/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/04_skip/why3session.xml b/creusot/tests/should_succeed/iterators/04_skip/why3session.xml
index 3c04a0e1b..f26037cfc 100644
--- a/creusot/tests/should_succeed/iterators/04_skip/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/04_skip/why3session.xml
@@ -3,37 +3,37 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="4" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="04_skip.mlcfg"/>
 <theory name="C04Skip_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="4"><result status="valid" time="0.025542" steps="8"/></proof>
+ <proof prover="1"><result status="valid" time="0.025542" steps="7"/></proof>
  </goal>
 </theory>
 <theory name="C04Skip_Impl0_ProducesTrans_Impl" proved="true">
  <goal name="produces_trans&#39;vc" expl="VC for produces_trans" proved="true">
  <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
   <goal name="produces_trans&#39;vc.0" expl="VC for produces_trans" proved="true">
-  <proof prover="0"><result status="valid" time="0.077298" steps="11627"/></proof>
+  <proof prover="0"><result status="valid" time="0.077298" steps="11365"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="C04Skip_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
- <proof prover="0"><result status="valid" time="0.657356" steps="89802"/></proof>
+ <proof prover="0"><result status="valid" time="0.244181" steps="90437"/></proof>
  </goal>
 </theory>
 <theory name="C04Skip_Impl0" proved="true">
  <goal name="produces_refl_refn" proved="true">
- <proof prover="4"><result status="valid" time="0.009950" steps="3"/></proof>
+ <proof prover="1"><result status="valid" time="0.009950" steps="2"/></proof>
  </goal>
  <goal name="next_refn" proved="true">
- <proof prover="4"><result status="valid" time="0.018475" steps="3"/></proof>
+ <proof prover="1"><result status="valid" time="0.018475" steps="2"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="4"><result status="valid" time="0.013593" steps="3"/></proof>
+ <proof prover="1"><result status="valid" time="0.013593" steps="2"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/04_skip/why3shapes.gz b/creusot/tests/should_succeed/iterators/04_skip/why3shapes.gz
index 20b994c37..b12488535 100644
Binary files a/creusot/tests/should_succeed/iterators/04_skip/why3shapes.gz and b/creusot/tests/should_succeed/iterators/04_skip/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/05_map/why3session.xml b/creusot/tests/should_succeed/iterators/05_map/why3session.xml
index 455d817c0..ccf52ff00 100644
--- a/creusot/tests/should_succeed/iterators/05_map/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/05_map/why3session.xml
@@ -2,10 +2,10 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="CVC4" version="1.8" timelimit="5" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="CVC5" version="1.0.5" timelimit="5" steplimit="0" memlimit="1000"/>
+<prover id="4" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="5" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="05_map.mlcfg"/>
 <theory name="C05Map_Impl0_ProducesRefl_Impl" proved="true">
@@ -19,7 +19,7 @@
     <proof prover="1"><result status="valid" time="0.000000" steps="4"/></proof>
     </goal>
     <goal name="produces_refl&#39;vc.0.0.1" expl="VC for produces_refl" proved="true">
-    <proof prover="0" timelimit="1"><result status="valid" time="0.110000" steps="29029"/></proof>
+    <proof prover="3" timelimit="1"><result status="valid" time="0.058430" steps="20326"/></proof>
     </goal>
    </transf>
    </goal>
@@ -38,51 +38,51 @@
     <goal name="produces_trans&#39;vc.0.0.0" expl="postcondition" proved="true">
     <transf name="split_vc" proved="true" >
      <goal name="produces_trans&#39;vc.0.0.0.0" expl="postcondition" proved="true">
-     <proof prover="1"><result status="valid" time="0.046186" steps="51"/></proof>
+     <proof prover="5"><result status="valid" time="0.046186" steps="51"/></proof>
      </goal>
      <goal name="produces_trans&#39;vc.0.0.0.1" expl="postcondition" proved="true">
      <transf name="exists" proved="true" arg1="(s1++s)">
       <goal name="produces_trans&#39;vc.0.0.0.1.0" proved="true">
       <transf name="split_vc" proved="true" >
        <goal name="produces_trans&#39;vc.0.0.0.1.0.0" proved="true">
-       <proof prover="1"><result status="valid" time="0.026979" steps="40"/></proof>
+       <proof prover="5"><result status="valid" time="0.026979" steps="40"/></proof>
        </goal>
        <goal name="produces_trans&#39;vc.0.0.0.1.0.1" proved="true">
-       <proof prover="1"><result status="valid" time="0.024061" steps="43"/></proof>
+       <proof prover="5"><result status="valid" time="0.024061" steps="43"/></proof>
        </goal>
        <goal name="produces_trans&#39;vc.0.0.0.1.0.2" proved="true">
-       <proof prover="1"><result status="valid" time="0.023577" steps="40"/></proof>
+       <proof prover="5"><result status="valid" time="0.023577" steps="40"/></proof>
        </goal>
        <goal name="produces_trans&#39;vc.0.0.0.1.0.3" proved="true">
        <transf name="exists" proved="true" arg1="(fs1++fs)">
         <goal name="produces_trans&#39;vc.0.0.0.1.0.3.0" proved="true">
         <transf name="split_vc" proved="true" >
          <goal name="produces_trans&#39;vc.0.0.0.1.0.3.0.0" proved="true">
-         <proof prover="1"><result status="valid" time="0.019616" steps="40"/></proof>
+         <proof prover="5"><result status="valid" time="0.019616" steps="40"/></proof>
          </goal>
          <goal name="produces_trans&#39;vc.0.0.0.1.0.3.0.1" proved="true">
-         <proof prover="1"><result status="valid" time="0.024308" steps="43"/></proof>
+         <proof prover="5"><result status="valid" time="0.024308" steps="43"/></proof>
          </goal>
          <goal name="produces_trans&#39;vc.0.0.0.1.0.3.0.2" proved="true">
-         <proof prover="1"><result status="valid" time="0.092190" steps="468"/></proof>
+         <proof prover="5"><result status="valid" time="0.092190" steps="468"/></proof>
          </goal>
          <goal name="produces_trans&#39;vc.0.0.0.1.0.3.0.3" proved="true">
-         <proof prover="1"><result status="valid" time="0.022108" steps="71"/></proof>
+         <proof prover="5"><result status="valid" time="0.022108" steps="71"/></proof>
          </goal>
          <goal name="produces_trans&#39;vc.0.0.0.1.0.3.0.4" proved="true">
-         <proof prover="1"><result status="valid" time="0.033641" steps="217"/></proof>
+         <proof prover="5"><result status="valid" time="0.033641" steps="217"/></proof>
          </goal>
          <goal name="produces_trans&#39;vc.0.0.0.1.0.3.0.5" proved="true">
-         <proof prover="1"><result status="valid" time="0.038581" steps="186"/></proof>
+         <proof prover="5"><result status="valid" time="0.038581" steps="186"/></proof>
          </goal>
          <goal name="produces_trans&#39;vc.0.0.0.1.0.3.0.6" proved="true">
-         <proof prover="1"><result status="valid" time="0.120127" steps="697"/></proof>
+         <proof prover="5"><result status="valid" time="0.120127" steps="696"/></proof>
          </goal>
          <goal name="produces_trans&#39;vc.0.0.0.1.0.3.0.7" proved="true">
-         <proof prover="1"><result status="valid" time="0.091713" steps="632"/></proof>
+         <proof prover="5"><result status="valid" time="0.091713" steps="632"/></proof>
          </goal>
          <goal name="produces_trans&#39;vc.0.0.0.1.0.3.0.8" proved="true">
-         <proof prover="1"><result status="valid" time="0.066844" steps="406"/></proof>
+         <proof prover="5"><result status="valid" time="0.066844" steps="406"/></proof>
          </goal>
         </transf>
         </goal>
@@ -111,25 +111,25 @@
     <goal name="produces_one&#39;vc.0.0.0" expl="postcondition" proved="true">
     <transf name="split_vc" proved="true" >
      <goal name="produces_one&#39;vc.0.0.0.0" expl="postcondition" proved="true">
-     <proof prover="1"><result status="valid" time="0.010000" steps="94"/></proof>
+     <proof prover="5"><result status="valid" time="0.010000" steps="94"/></proof>
      </goal>
      <goal name="produces_one&#39;vc.0.0.0.1" expl="postcondition" proved="true">
      <transf name="exists" proved="true" arg1="(singleton e)">
       <goal name="produces_one&#39;vc.0.0.0.1.0" proved="true">
       <transf name="split_vc" proved="true" >
        <goal name="produces_one&#39;vc.0.0.0.1.0.0" proved="true">
-       <proof prover="1"><result status="valid" time="0.023917" steps="22"/></proof>
+       <proof prover="5"><result status="valid" time="0.023917" steps="22"/></proof>
        </goal>
        <goal name="produces_one&#39;vc.0.0.0.1.0.1" proved="true">
-       <proof prover="1"><result status="valid" time="0.010000" steps="22"/></proof>
+       <proof prover="5"><result status="valid" time="0.010000" steps="22"/></proof>
        </goal>
        <goal name="produces_one&#39;vc.0.0.0.1.0.2" proved="true">
-       <proof prover="1"><result status="valid" time="0.010000" steps="20"/></proof>
+       <proof prover="5"><result status="valid" time="0.010000" steps="20"/></proof>
        </goal>
        <goal name="produces_one&#39;vc.0.0.0.1.0.3" proved="true">
        <transf name="exists" proved="true" arg1="(singleton f)">
         <goal name="produces_one&#39;vc.0.0.0.1.0.3.0" proved="true">
-        <proof prover="1" timelimit="5"><result status="valid" time="0.010000" steps="195"/></proof>
+        <proof prover="5" timelimit="5"><result status="valid" time="0.010000" steps="195"/></proof>
         </goal>
        </transf>
        </goal>
@@ -144,7 +144,7 @@
    <goal name="produces_one&#39;vc.0.1" expl="postcondition" proved="true">
    <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
     <goal name="produces_one&#39;vc.0.1.0" expl="postcondition" proved="true">
-    <proof prover="3" memlimit="2000"><result status="valid" time="0.114723" steps="32656"/></proof>
+    <proof prover="3" memlimit="2000"><result status="valid" time="0.114723" steps="32649"/></proof>
     </goal>
    </transf>
    </goal>
@@ -159,13 +159,13 @@
   <goal name="produces_one_invariant&#39;vc.0" expl="VC for produces_one_invariant" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="produces_one_invariant&#39;vc.0.0" expl="assertion" proved="true">
-   <proof prover="0"><result status="valid" time="0.045738" steps="19659"/></proof>
+   <proof prover="3"><result status="valid" time="0.040690" steps="15246"/></proof>
    </goal>
    <goal name="produces_one_invariant&#39;vc.0.1" expl="postcondition" proved="true">
-   <proof prover="1" timelimit="5" memlimit="2000"><result status="valid" time="0.059818" steps="1306"/></proof>
+   <proof prover="5" timelimit="5" memlimit="2000"><result status="valid" time="0.059818" steps="1295"/></proof>
    </goal>
    <goal name="produces_one_invariant&#39;vc.0.2" expl="postcondition" proved="true">
-   <proof prover="3"><result status="valid" time="0.078660" steps="25984"/></proof>
+   <proof prover="3"><result status="valid" time="0.078660" steps="25079"/></proof>
    </goal>
   </transf>
   </goal>
@@ -176,58 +176,58 @@
  <goal name="next&#39;vc" expl="VC for next" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="next&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.022767" steps="15"/></proof>
+  <proof prover="5"><result status="valid" time="0.022767" steps="15"/></proof>
   </goal>
   <goal name="next&#39;vc.1" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.034554" steps="16"/></proof>
+  <proof prover="5"><result status="valid" time="0.034554" steps="16"/></proof>
   </goal>
   <goal name="next&#39;vc.2" expl="type invariant" proved="true">
-  <proof prover="3" timelimit="1"><result status="valid" time="0.088091" steps="11286"/></proof>
+  <proof prover="3" timelimit="1"><result status="valid" time="0.088091" steps="11185"/></proof>
   </goal>
   <goal name="next&#39;vc.3" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.020531" steps="26"/></proof>
+  <proof prover="5"><result status="valid" time="0.020531" steps="26"/></proof>
   </goal>
   <goal name="next&#39;vc.4" expl="assertion" proved="true">
-  <proof prover="1"><result status="valid" time="0.039048" steps="203"/></proof>
+  <proof prover="5"><result status="valid" time="0.039048" steps="203"/></proof>
   </goal>
   <goal name="next&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.019493" steps="39"/></proof>
+  <proof prover="5"><result status="valid" time="0.019493" steps="39"/></proof>
   </goal>
   <goal name="next&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.016233" steps="49"/></proof>
+  <proof prover="5"><result status="valid" time="0.016233" steps="49"/></proof>
   </goal>
   <goal name="next&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.021483" steps="49"/></proof>
+  <proof prover="5"><result status="valid" time="0.021483" steps="49"/></proof>
   </goal>
   <goal name="next&#39;vc.8" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.053798" steps="18342"/></proof>
+  <proof prover="3"><result status="valid" time="0.031142" steps="13449"/></proof>
   </goal>
   <goal name="next&#39;vc.9" expl="unreachable point" proved="true">
-  <proof prover="1"><result status="valid" time="0.028356" steps="23"/></proof>
+  <proof prover="5"><result status="valid" time="0.028356" steps="23"/></proof>
   </goal>
   <goal name="next&#39;vc.10" expl="postcondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.220967" steps="793735"/></proof>
+  <proof prover="4"><result status="valid" time="0.220967" steps="522176"/></proof>
   </goal>
   <goal name="next&#39;vc.11" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.023519" steps="7"/></proof>
+  <proof prover="5"><result status="valid" time="0.023519" steps="7"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="C05Map_Map" proved="true">
  <goal name="map&#39;vc" expl="VC for map" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="69"/></proof>
+ <proof prover="5"><result status="valid" time="0.010000" steps="69"/></proof>
  </goal>
 </theory>
 <theory name="C05Map_Impl0" proved="true">
  <goal name="produces_trans_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="0"/></proof>
+ <proof prover="5"><result status="valid" time="0.000000" steps="0"/></proof>
  </goal>
  <goal name="next_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="599"/></proof>
+ <proof prover="5"><result status="valid" time="0.010000" steps="609"/></proof>
  </goal>
  <goal name="produces_refl_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="0"/></proof>
+ <proof prover="5"><result status="valid" time="0.000000" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/05_map/why3shapes.gz b/creusot/tests/should_succeed/iterators/05_map/why3shapes.gz
index 388bb90dc..11885880a 100644
Binary files a/creusot/tests/should_succeed/iterators/05_map/why3shapes.gz and b/creusot/tests/should_succeed/iterators/05_map/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/06_map_precond/why3session.xml b/creusot/tests/should_succeed/iterators/06_map_precond/why3session.xml
index ff670a8ab..7edf883d5 100644
--- a/creusot/tests/should_succeed/iterators/06_map_precond/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/06_map_precond/why3session.xml
@@ -2,9 +2,7 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="3" name="CVC4" version="1.8" timelimit="5" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="4" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="06_map_precond.mlcfg"/>
@@ -12,7 +10,7 @@
  <goal name="preservation_inv&#39;vc" expl="VC for preservation_inv" proved="true">
  <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
   <goal name="preservation_inv&#39;vc.0" expl="VC for preservation_inv" proved="true">
-  <proof prover="4"><result status="valid" time="0.076544" steps="43576"/></proof>
+  <proof prover="4"><result status="valid" time="0.076544" steps="45325"/></proof>
   </goal>
  </transf>
  </goal>
@@ -25,7 +23,7 @@
    <goal name="produces_refl&#39;vc.0.0" expl="postcondition" proved="true">
    <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
     <goal name="produces_refl&#39;vc.0.0.0" expl="postcondition" proved="true">
-    <proof prover="4"><result status="valid" time="0.234741" steps="36336"/></proof>
+    <proof prover="4"><result status="valid" time="0.234741" steps="39281"/></proof>
     </goal>
    </transf>
    </goal>
@@ -40,25 +38,25 @@
   <goal name="produces_trans&#39;vc.0" expl="VC for produces_trans" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="produces_trans&#39;vc.0.0" expl="VC for produces_trans" proved="true">
-   <proof prover="1"><result status="valid" time="0.010000" steps="54"/></proof>
+   <proof prover="0"><result status="valid" time="0.010000" steps="54"/></proof>
    </goal>
    <goal name="produces_trans&#39;vc.0.1" expl="VC for produces_trans" proved="true">
    <transf name="exists" proved="true" arg1="(s1 ++ s)">
     <goal name="produces_trans&#39;vc.0.1.0" proved="true">
     <transf name="split_vc" proved="true" >
      <goal name="produces_trans&#39;vc.0.1.0.0" proved="true">
-     <proof prover="1"><result status="valid" time="0.028099" steps="44"/></proof>
+     <proof prover="0"><result status="valid" time="0.028099" steps="44"/></proof>
      </goal>
      <goal name="produces_trans&#39;vc.0.1.0.1" proved="true">
-     <proof prover="1"><result status="valid" time="0.010000" steps="50"/></proof>
+     <proof prover="0"><result status="valid" time="0.010000" steps="50"/></proof>
      </goal>
      <goal name="produces_trans&#39;vc.0.1.0.2" proved="true">
-     <proof prover="1"><result status="valid" time="0.010000" steps="44"/></proof>
+     <proof prover="0"><result status="valid" time="0.010000" steps="44"/></proof>
      </goal>
      <goal name="produces_trans&#39;vc.0.1.0.3" proved="true">
      <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
       <goal name="produces_trans&#39;vc.0.1.0.3.0" proved="true">
-      <proof prover="1"><result status="valid" time="0.010000" steps="49"/></proof>
+      <proof prover="0"><result status="valid" time="0.010000" steps="49"/></proof>
       </goal>
      </transf>
      </goal>
@@ -67,25 +65,25 @@
       <goal name="produces_trans&#39;vc.0.1.0.4.0" proved="true">
       <transf name="split_vc" proved="true" >
        <goal name="produces_trans&#39;vc.0.1.0.4.0.0" proved="true">
-       <proof prover="1"><result status="valid" time="0.040708" steps="44"/></proof>
+       <proof prover="0"><result status="valid" time="0.040708" steps="44"/></proof>
        </goal>
        <goal name="produces_trans&#39;vc.0.1.0.4.0.1" proved="true">
-       <proof prover="1"><result status="valid" time="0.010000" steps="50"/></proof>
+       <proof prover="0"><result status="valid" time="0.010000" steps="50"/></proof>
        </goal>
        <goal name="produces_trans&#39;vc.0.1.0.4.0.2" proved="true">
-       <proof prover="1"><result status="valid" time="0.039524" steps="588"/></proof>
+       <proof prover="0"><result status="valid" time="0.039524" steps="586"/></proof>
        </goal>
        <goal name="produces_trans&#39;vc.0.1.0.4.0.3" proved="true">
-       <proof prover="1"><result status="valid" time="0.010000" steps="88"/></proof>
+       <proof prover="0"><result status="valid" time="0.010000" steps="88"/></proof>
        </goal>
        <goal name="produces_trans&#39;vc.0.1.0.4.0.4" proved="true">
-       <proof prover="1"><result status="valid" time="0.030000" steps="274"/></proof>
+       <proof prover="0"><result status="valid" time="0.030000" steps="274"/></proof>
        </goal>
        <goal name="produces_trans&#39;vc.0.1.0.4.0.5" proved="true">
-       <proof prover="1"><result status="valid" time="0.020000" steps="230"/></proof>
+       <proof prover="0"><result status="valid" time="0.020000" steps="230"/></proof>
        </goal>
        <goal name="produces_trans&#39;vc.0.1.0.4.0.6" proved="true">
-       <proof prover="1"><result status="valid" time="0.150000" steps="620"/></proof>
+       <proof prover="0"><result status="valid" time="0.150000" steps="618"/></proof>
        </goal>
        <goal name="produces_trans&#39;vc.0.1.0.4.0.7" proved="true">
        <transf name="instantiate" proved="true" arg1="H2" arg2="(i-length ab)">
@@ -94,7 +92,7 @@
          <goal name="produces_trans&#39;vc.0.1.0.4.0.7.0.0" proved="true">
          <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
           <goal name="produces_trans&#39;vc.0.1.0.4.0.7.0.0.0" proved="true">
-          <proof prover="1"><result status="valid" time="0.507833" steps="7131"/></proof>
+          <proof prover="0"><result status="valid" time="0.507833" steps="7161"/></proof>
           </goal>
          </transf>
          </goal>
@@ -109,7 +107,7 @@
          <goal name="produces_trans&#39;vc.0.1.0.4.0.8.0.0" proved="true">
          <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
           <goal name="produces_trans&#39;vc.0.1.0.4.0.8.0.0.0" proved="true">
-          <proof prover="1" timelimit="30" memlimit="4000"><result status="valid" time="0.463977" steps="6429"/></proof>
+          <proof prover="0" timelimit="30" memlimit="4000"><result status="valid" time="0.463977" steps="6890"/></proof>
           </goal>
          </transf>
          </goal>
@@ -140,25 +138,25 @@
     <goal name="produces_one&#39;vc.0.0.0" expl="VC for produces_one" proved="true">
     <transf name="split_vc" proved="true" >
      <goal name="produces_one&#39;vc.0.0.0.0" expl="VC for produces_one" proved="true">
-     <proof prover="1"><result status="valid" time="0.010000" steps="118"/></proof>
+     <proof prover="0"><result status="valid" time="0.010000" steps="118"/></proof>
      </goal>
      <goal name="produces_one&#39;vc.0.0.0.1" expl="VC for produces_one" proved="true">
      <transf name="exists" proved="true" arg1="(singleton e)">
       <goal name="produces_one&#39;vc.0.0.0.1.0" proved="true">
       <transf name="split_vc" proved="true" >
        <goal name="produces_one&#39;vc.0.0.0.1.0.0" proved="true">
-       <proof prover="1"><result status="valid" time="0.023538" steps="24"/></proof>
+       <proof prover="0"><result status="valid" time="0.023538" steps="24"/></proof>
        </goal>
        <goal name="produces_one&#39;vc.0.0.0.1.0.1" proved="true">
-       <proof prover="1"><result status="valid" time="0.010000" steps="26"/></proof>
+       <proof prover="0"><result status="valid" time="0.010000" steps="26"/></proof>
        </goal>
        <goal name="produces_one&#39;vc.0.0.0.1.0.2" proved="true">
-       <proof prover="1"><result status="valid" time="0.010000" steps="22"/></proof>
+       <proof prover="0"><result status="valid" time="0.010000" steps="22"/></proof>
        </goal>
        <goal name="produces_one&#39;vc.0.0.0.1.0.3" proved="true">
        <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
         <goal name="produces_one&#39;vc.0.0.0.1.0.3.0" proved="true">
-        <proof prover="1"><result status="valid" time="0.010000" steps="24"/></proof>
+        <proof prover="0"><result status="valid" time="0.010000" steps="24"/></proof>
         </goal>
        </transf>
        </goal>
@@ -167,37 +165,37 @@
         <goal name="produces_one&#39;vc.0.0.0.1.0.4.0" proved="true">
         <transf name="split_vc" proved="true" >
          <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.0" proved="true">
-         <proof prover="1"><result status="valid" time="0.026703" steps="24"/></proof>
+         <proof prover="0"><result status="valid" time="0.026703" steps="24"/></proof>
          </goal>
          <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.1" proved="true">
-         <proof prover="1"><result status="valid" time="0.010000" steps="28"/></proof>
+         <proof prover="0"><result status="valid" time="0.010000" steps="28"/></proof>
          </goal>
          <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.2" proved="true">
-         <proof prover="1"><result status="valid" time="0.010000" steps="28"/></proof>
+         <proof prover="0"><result status="valid" time="0.010000" steps="28"/></proof>
          </goal>
          <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.3" proved="true">
-         <proof prover="1"><result status="valid" time="0.010000" steps="26"/></proof>
+         <proof prover="0"><result status="valid" time="0.010000" steps="26"/></proof>
          </goal>
          <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.4" proved="true">
-         <proof prover="1"><result status="valid" time="0.010000" steps="26"/></proof>
+         <proof prover="0"><result status="valid" time="0.010000" steps="26"/></proof>
          </goal>
          <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.5" proved="true">
-         <proof prover="1"><result status="valid" time="0.010000" steps="28"/></proof>
+         <proof prover="0"><result status="valid" time="0.010000" steps="28"/></proof>
          </goal>
          <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.6" proved="true">
-         <proof prover="1"><result status="valid" time="0.010000" steps="43"/></proof>
+         <proof prover="0"><result status="valid" time="0.010000" steps="43"/></proof>
          </goal>
          <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.7" proved="true">
          <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
           <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.7.0" proved="true">
-          <proof prover="1"><result status="valid" time="0.030000" steps="405"/></proof>
+          <proof prover="0"><result status="valid" time="0.030000" steps="398"/></proof>
           </goal>
          </transf>
          </goal>
          <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.8" proved="true">
          <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
           <goal name="produces_one&#39;vc.0.0.0.1.0.4.0.8.0" proved="true">
-          <proof prover="1"><result status="valid" time="0.143126" steps="409"/></proof>
+          <proof prover="0"><result status="valid" time="0.027700" steps="402"/></proof>
           </goal>
          </transf>
          </goal>
@@ -216,7 +214,7 @@
    <goal name="produces_one&#39;vc.0.1" expl="postcondition" proved="true">
    <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
     <goal name="produces_one&#39;vc.0.1.0" expl="postcondition" proved="true">
-    <proof prover="4"><result status="valid" time="0.128957" steps="39034"/></proof>
+    <proof prover="4"><result status="valid" time="0.128957" steps="38075"/></proof>
     </goal>
    </transf>
    </goal>
@@ -231,13 +229,13 @@
   <goal name="produces_one_invariant&#39;vc.0" expl="VC for produces_one_invariant" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="produces_one_invariant&#39;vc.0.0" expl="assertion" proved="true">
-   <proof prover="3"><result status="valid" time="0.054265" steps="22895"/></proof>
+   <proof prover="4" timelimit="5"><result status="valid" time="0.042988" steps="17223"/></proof>
    </goal>
    <goal name="produces_one_invariant&#39;vc.0.1" expl="postcondition" proved="true">
-   <proof prover="1" timelimit="5" memlimit="2000"><result status="valid" time="0.096337" steps="1876"/></proof>
+   <proof prover="0" timelimit="5" memlimit="2000"><result status="valid" time="0.096337" steps="1828"/></proof>
    </goal>
    <goal name="produces_one_invariant&#39;vc.0.2" expl="postcondition" proved="true">
-   <proof prover="4" timelimit="5"><result status="valid" time="0.335330" steps="84441"/></proof>
+   <proof prover="4" timelimit="5"><result status="valid" time="0.335330" steps="76040"/></proof>
    </goal>
   </transf>
   </goal>
@@ -248,43 +246,43 @@
  <goal name="next&#39;vc" expl="VC for next" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="next&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.015246" steps="18"/></proof>
+  <proof prover="0"><result status="valid" time="0.015246" steps="18"/></proof>
   </goal>
   <goal name="next&#39;vc.1" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.024082" steps="19"/></proof>
+  <proof prover="0"><result status="valid" time="0.024082" steps="18"/></proof>
   </goal>
   <goal name="next&#39;vc.2" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.079981" steps="17513"/></proof>
+  <proof prover="4" timelimit="5"><result status="valid" time="0.024310" steps="12268"/></proof>
   </goal>
   <goal name="next&#39;vc.3" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.013144" steps="411"/></proof>
+  <proof prover="0"><result status="valid" time="0.013144" steps="410"/></proof>
   </goal>
   <goal name="next&#39;vc.4" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.024006" steps="29"/></proof>
+  <proof prover="0"><result status="valid" time="0.024006" steps="29"/></proof>
   </goal>
   <goal name="next&#39;vc.5" expl="assertion" proved="true">
-  <proof prover="1"><result status="valid" time="0.025172" steps="170"/></proof>
+  <proof prover="0"><result status="valid" time="0.025172" steps="170"/></proof>
   </goal>
   <goal name="next&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.015449" steps="65"/></proof>
+  <proof prover="0"><result status="valid" time="0.015449" steps="64"/></proof>
   </goal>
   <goal name="next&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.013939" steps="63"/></proof>
+  <proof prover="0"><result status="valid" time="0.013939" steps="62"/></proof>
   </goal>
   <goal name="next&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.015299" steps="64"/></proof>
+  <proof prover="0"><result status="valid" time="0.015299" steps="63"/></proof>
   </goal>
   <goal name="next&#39;vc.9" expl="type invariant" proved="true">
-  <proof prover="4"><result status="valid" time="0.136766" steps="14883"/></proof>
+  <proof prover="4"><result status="valid" time="0.136766" steps="14624"/></proof>
   </goal>
   <goal name="next&#39;vc.10" expl="type invariant" proved="true">
-  <proof prover="4"><result status="valid" time="0.113274" steps="21563"/></proof>
+  <proof prover="4"><result status="valid" time="0.113274" steps="21386"/></proof>
   </goal>
   <goal name="next&#39;vc.11" expl="unreachable point" proved="true">
-  <proof prover="1"><result status="valid" time="0.012501" steps="27"/></proof>
+  <proof prover="0"><result status="valid" time="0.012501" steps="26"/></proof>
   </goal>
   <goal name="next&#39;vc.12" expl="postcondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.073346" steps="26610"/></proof>
+  <proof prover="4"><result status="valid" time="0.073346" steps="26481"/></proof>
   </goal>
   <goal name="next&#39;vc.13" expl="postcondition" proved="true">
   <proof prover="0"><result status="valid" time="0.015445" steps="7"/></proof>
@@ -294,70 +292,70 @@
 </theory>
 <theory name="C06MapPrecond_Map" proved="true">
  <goal name="map&#39;vc" expl="VC for map" proved="true">
- <proof prover="3"><result status="valid" time="0.044619" steps="15839"/></proof>
+ <proof prover="4" timelimit="5"><result status="valid" time="0.025025" steps="10257"/></proof>
  </goal>
 </theory>
 <theory name="C06MapPrecond_Identity_Closure0" proved="true">
  <goal name="c06MapPrecond_Identity_Closure0&#39;vc" expl="VC for c06MapPrecond_Identity_Closure0" proved="true">
- <proof prover="1"><result status="valid" time="0.012451" steps="6"/></proof>
+ <proof prover="0"><result status="valid" time="0.012451" steps="6"/></proof>
  </goal>
 </theory>
 <theory name="C06MapPrecond_Identity" proved="true">
  <goal name="identity&#39;vc" expl="VC for identity" proved="true">
- <proof prover="1"><result status="valid" time="0.025832" steps="253"/></proof>
+ <proof prover="0"><result status="valid" time="0.025832" steps="253"/></proof>
  </goal>
 </theory>
 <theory name="C06MapPrecond_Increment_Closure2" proved="true">
  <goal name="c06MapPrecond_Increment_Closure2&#39;vc" expl="VC for c06MapPrecond_Increment_Closure2" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="12"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="12"/></proof>
  </goal>
 </theory>
 <theory name="C06MapPrecond_Increment" proved="true">
  <goal name="increment&#39;vc" expl="VC for increment" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="increment&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="38"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="38"/></proof>
   </goal>
   <goal name="increment&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.040000" steps="226"/></proof>
+  <proof prover="0"><result status="valid" time="0.040000" steps="226"/></proof>
   </goal>
   <goal name="increment&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="132"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="132"/></proof>
   </goal>
   <goal name="increment&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="8"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="8"/></proof>
   </goal>
   <goal name="increment&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.016718" steps="10"/></proof>
+  <proof prover="0"><result status="valid" time="0.016718" steps="10"/></proof>
   </goal>
   <goal name="increment&#39;vc.5" expl="type invariant" proved="true">
-  <proof prover="1" timelimit="5"><result status="valid" time="0.026428" steps="8"/></proof>
+  <proof prover="0" timelimit="5"><result status="valid" time="0.026428" steps="8"/></proof>
   </goal>
   <goal name="increment&#39;vc.6" expl="assertion" proved="true">
-  <proof prover="3" timelimit="1"><result status="valid" time="0.217347" steps="43838"/></proof>
+  <proof prover="4"><result status="valid" time="0.774023" steps="224920"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="C06MapPrecond_Counter_Closure2" proved="true">
  <goal name="c06MapPrecond_Counter_Closure2&#39;vc" expl="VC for c06MapPrecond_Counter_Closure2" proved="true">
- <proof prover="1"><result status="valid" time="0.020000" steps="124"/></proof>
+ <proof prover="0"><result status="valid" time="0.020000" steps="124"/></proof>
  </goal>
 </theory>
 <theory name="C06MapPrecond_Counter" proved="true">
  <goal name="counter&#39;vc" expl="VC for counter" proved="true">
- <proof prover="1"><result status="valid" time="0.054988" steps="809"/></proof>
+ <proof prover="0"><result status="valid" time="0.054988" steps="808"/></proof>
  </goal>
 </theory>
 <theory name="C06MapPrecond_Impl0" proved="true">
  <goal name="produces_refl_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="0"/></proof>
  </goal>
  <goal name="next_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.079489" steps="1292"/></proof>
+ <proof prover="0"><result status="valid" time="0.079489" steps="1269"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/06_map_precond/why3shapes.gz b/creusot/tests/should_succeed/iterators/06_map_precond/why3shapes.gz
index 48584ee07..f14f993e7 100644
Binary files a/creusot/tests/should_succeed/iterators/06_map_precond/why3shapes.gz and b/creusot/tests/should_succeed/iterators/06_map_precond/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/07_fuse/why3session.xml b/creusot/tests/should_succeed/iterators/07_fuse/why3session.xml
index 3441e96b9..1747bd15e 100644
--- a/creusot/tests/should_succeed/iterators/07_fuse/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/07_fuse/why3session.xml
@@ -2,18 +2,18 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="07_fuse.mlcfg"/>
 <theory name="C07Fuse_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
- <proof prover="2"><result status="valid" time="0.312791" steps="1739"/></proof>
+ <proof prover="0"><result status="valid" time="0.087006" steps="1738"/></proof>
  </goal>
 </theory>
 <theory name="C07Fuse_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="2"><result status="valid" time="0.010276" steps="40"/></proof>
+ <proof prover="0"><result status="valid" time="0.010276" steps="39"/></proof>
  </goal>
 </theory>
 <theory name="C07Fuse_Impl0_ProducesTrans_Impl" proved="true">
@@ -26,7 +26,7 @@
     <goal name="produces_trans&#39;vc.0.0.0" expl="postcondition" proved="true">
     <transf name="inline_goal" proved="true" >
      <goal name="produces_trans&#39;vc.0.0.0.0" expl="postcondition" proved="true">
-     <proof prover="1"><result status="valid" time="0.127221" steps="21649"/></proof>
+     <proof prover="1"><result status="valid" time="0.127221" steps="19157"/></proof>
      </goal>
     </transf>
     </goal>
@@ -39,23 +39,23 @@
 </theory>
 <theory name="C07Fuse_Impl1_IsFused_Impl" proved="true">
  <goal name="is_fused&#39;vc" expl="VC for is_fused" proved="true">
- <proof prover="2"><result status="valid" time="0.020265" steps="34"/></proof>
+ <proof prover="0"><result status="valid" time="0.020265" steps="34"/></proof>
  </goal>
 </theory>
 <theory name="C07Fuse_Impl0" proved="true">
  <goal name="produces_refl_refn" proved="true">
- <proof prover="2"><result status="valid" time="0.007161" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.007161" steps="0"/></proof>
  </goal>
  <goal name="next_refn" proved="true">
- <proof prover="2"><result status="valid" time="0.007088" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.007088" steps="0"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="2"><result status="valid" time="0.007298" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.007298" steps="0"/></proof>
  </goal>
 </theory>
 <theory name="C07Fuse_Impl1" proved="true">
  <goal name="is_fused_refn" proved="true">
- <proof prover="2"><result status="valid" time="0.013355" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.013355" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/07_fuse/why3shapes.gz b/creusot/tests/should_succeed/iterators/07_fuse/why3shapes.gz
index 96d2692c5..7b1105150 100644
Binary files a/creusot/tests/should_succeed/iterators/07_fuse/why3shapes.gz and b/creusot/tests/should_succeed/iterators/07_fuse/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/08_collect_extend/why3session.xml b/creusot/tests/should_succeed/iterators/08_collect_extend/why3session.xml
index fef94b7c8..2dc2ffb91 100644
--- a/creusot/tests/should_succeed/iterators/08_collect_extend/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/08_collect_extend/why3session.xml
@@ -2,83 +2,83 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="08_collect_extend.mlcfg"/>
 <theory name="C08CollectExtend_Extend" proved="true">
  <goal name="extend&#39;vc" expl="VC for extend" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="extend&#39;vc.0" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.019703" steps="10"/></proof>
+  <proof prover="0"><result status="valid" time="0.019703" steps="10"/></proof>
   </goal>
   <goal name="extend&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="12"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="12"/></proof>
   </goal>
   <goal name="extend&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="12"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="12"/></proof>
   </goal>
   <goal name="extend&#39;vc.3" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.018437" steps="19"/></proof>
+  <proof prover="0"><result status="valid" time="0.018437" steps="19"/></proof>
   </goal>
   <goal name="extend&#39;vc.4" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.023618" steps="25"/></proof>
+  <proof prover="0"><result status="valid" time="0.023618" steps="25"/></proof>
   </goal>
   <goal name="extend&#39;vc.5" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="27"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="27"/></proof>
   </goal>
   <goal name="extend&#39;vc.6" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="29"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="29"/></proof>
   </goal>
   <goal name="extend&#39;vc.7" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="31"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="31"/></proof>
   </goal>
   <goal name="extend&#39;vc.8" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="106"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="106"/></proof>
   </goal>
   <goal name="extend&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.007873" steps="49"/></proof>
+  <proof prover="0"><result status="valid" time="0.007873" steps="49"/></proof>
   </goal>
   <goal name="extend&#39;vc.10" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.013205" steps="52"/></proof>
+  <proof prover="0"><result status="valid" time="0.013205" steps="52"/></proof>
   </goal>
   <goal name="extend&#39;vc.11" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.016013" steps="57"/></proof>
+  <proof prover="0"><result status="valid" time="0.016013" steps="57"/></proof>
   </goal>
   <goal name="extend&#39;vc.12" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.010335" steps="59"/></proof>
+  <proof prover="0"><result status="valid" time="0.010335" steps="59"/></proof>
   </goal>
   <goal name="extend&#39;vc.13" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.024194" steps="64"/></proof>
+  <proof prover="0"><result status="valid" time="0.024194" steps="64"/></proof>
   </goal>
   <goal name="extend&#39;vc.14" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="181"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="183"/></proof>
   </goal>
   <goal name="extend&#39;vc.15" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.016717" steps="64"/></proof>
+  <proof prover="0"><result status="valid" time="0.016717" steps="64"/></proof>
   </goal>
   <goal name="extend&#39;vc.16" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.018691" steps="78"/></proof>
+  <proof prover="0"><result status="valid" time="0.018691" steps="78"/></proof>
   </goal>
   <goal name="extend&#39;vc.17" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.023970" steps="90"/></proof>
+  <proof prover="0"><result status="valid" time="0.023970" steps="90"/></proof>
   </goal>
   <goal name="extend&#39;vc.18" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="92"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="92"/></proof>
   </goal>
   <goal name="extend&#39;vc.19" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.000000" steps="89"/></proof>
+  <proof prover="0"><result status="valid" time="0.000000" steps="89"/></proof>
   </goal>
   <goal name="extend&#39;vc.20" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="358"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="326"/></proof>
   </goal>
   <goal name="extend&#39;vc.21" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="92"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="92"/></proof>
   </goal>
   <goal name="extend&#39;vc.22" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.046107" steps="836"/></proof>
+  <proof prover="0"><result status="valid" time="0.046107" steps="739"/></proof>
   </goal>
   <goal name="extend&#39;vc.23" expl="unreachable point" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="61"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="61"/></proof>
   </goal>
  </transf>
  </goal>
@@ -87,79 +87,79 @@
  <goal name="collect&#39;vc" expl="VC for collect" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="collect&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="8"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="8"/></proof>
   </goal>
   <goal name="collect&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.003608" steps="8"/></proof>
+  <proof prover="0"><result status="valid" time="0.003608" steps="8"/></proof>
   </goal>
   <goal name="collect&#39;vc.2" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.018857" steps="15"/></proof>
+  <proof prover="0"><result status="valid" time="0.018857" steps="15"/></proof>
   </goal>
   <goal name="collect&#39;vc.3" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.021500" steps="21"/></proof>
+  <proof prover="0"><result status="valid" time="0.021500" steps="21"/></proof>
   </goal>
   <goal name="collect&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="23"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="23"/></proof>
   </goal>
   <goal name="collect&#39;vc.5" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="25"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="25"/></proof>
   </goal>
   <goal name="collect&#39;vc.6" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="49"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="49"/></proof>
   </goal>
   <goal name="collect&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.011297" steps="41"/></proof>
+  <proof prover="0"><result status="valid" time="0.011297" steps="41"/></proof>
   </goal>
   <goal name="collect&#39;vc.8" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.012200" steps="44"/></proof>
+  <proof prover="0"><result status="valid" time="0.012200" steps="44"/></proof>
   </goal>
   <goal name="collect&#39;vc.9" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.016742" steps="49"/></proof>
+  <proof prover="0"><result status="valid" time="0.016742" steps="49"/></proof>
   </goal>
   <goal name="collect&#39;vc.10" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.015019" steps="51"/></proof>
+  <proof prover="0"><result status="valid" time="0.015019" steps="51"/></proof>
   </goal>
   <goal name="collect&#39;vc.11" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="94"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="94"/></proof>
   </goal>
   <goal name="collect&#39;vc.12" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.012638" steps="66"/></proof>
+  <proof prover="0"><result status="valid" time="0.012638" steps="66"/></proof>
   </goal>
   <goal name="collect&#39;vc.13" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.010461" steps="56"/></proof>
+  <proof prover="0"><result status="valid" time="0.010461" steps="56"/></proof>
   </goal>
   <goal name="collect&#39;vc.14" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.017184" steps="70"/></proof>
+  <proof prover="0"><result status="valid" time="0.017184" steps="70"/></proof>
   </goal>
   <goal name="collect&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="80"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="80"/></proof>
   </goal>
   <goal name="collect&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="82"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="82"/></proof>
   </goal>
   <goal name="collect&#39;vc.17" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="79"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="79"/></proof>
   </goal>
   <goal name="collect&#39;vc.18" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="296"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="295"/></proof>
   </goal>
   <goal name="collect&#39;vc.19" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.020000" steps="359"/></proof>
+  <proof prover="0"><result status="valid" time="0.020000" steps="358"/></proof>
   </goal>
   <goal name="collect&#39;vc.20" expl="unreachable point" proved="true">
-  <proof prover="1"><result status="valid" time="0.010000" steps="53"/></proof>
+  <proof prover="0"><result status="valid" time="0.010000" steps="53"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="C08CollectExtend_ExtendIndex" proved="true">
  <goal name="extend_index&#39;vc" expl="VC for extend_index" proved="true">
- <proof prover="1"><result status="valid" time="0.040000" steps="380"/></proof>
+ <proof prover="0"><result status="valid" time="0.040000" steps="383"/></proof>
  </goal>
 </theory>
 <theory name="C08CollectExtend_CollectExample" proved="true">
  <goal name="collect_example&#39;vc" expl="VC for collect_example" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="62"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="62"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/08_collect_extend/why3shapes.gz b/creusot/tests/should_succeed/iterators/08_collect_extend/why3shapes.gz
index b5dd105c7..a9db487dd 100644
Binary files a/creusot/tests/should_succeed/iterators/08_collect_extend/why3shapes.gz and b/creusot/tests/should_succeed/iterators/08_collect_extend/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/09_empty/why3session.xml b/creusot/tests/should_succeed/iterators/09_empty/why3session.xml
index ce9f8a66d..17e60e574 100644
--- a/creusot/tests/should_succeed/iterators/09_empty/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/09_empty/why3session.xml
@@ -2,33 +2,33 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="09_empty.mlcfg"/>
 <theory name="C09Empty_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="4"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="4"/></proof>
  </goal>
 </theory>
 <theory name="C09Empty_Impl0_ProducesTrans_Impl" proved="true">
  <goal name="produces_trans&#39;vc" expl="VC for produces_trans" proved="true">
- <proof prover="1"><result status="valid" time="0.140000" steps="1852"/></proof>
+ <proof prover="0"><result status="valid" time="0.140000" steps="1851"/></proof>
  </goal>
 </theory>
 <theory name="C09Empty_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="20"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="20"/></proof>
  </goal>
 </theory>
 <theory name="C09Empty_Impl0" proved="true">
  <goal name="produces_trans_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="14"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="14"/></proof>
  </goal>
  <goal name="produces_refl_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="0"/></proof>
  </goal>
  <goal name="next_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/09_empty/why3shapes.gz b/creusot/tests/should_succeed/iterators/09_empty/why3shapes.gz
index 9812fa9ae..18ae5acbd 100644
Binary files a/creusot/tests/should_succeed/iterators/09_empty/why3shapes.gz and b/creusot/tests/should_succeed/iterators/09_empty/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/10_once/why3session.xml b/creusot/tests/should_succeed/iterators/10_once/why3session.xml
index 6fc2952e6..f80e28433 100644
--- a/creusot/tests/should_succeed/iterators/10_once/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/10_once/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="2" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="10_once.mlcfg"/>
 <theory name="C10Once_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="2"><result status="valid" time="0.000000" steps="6"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="6"/></proof>
  </goal>
 </theory>
 <theory name="C10Once_Impl0_ProducesTrans_Impl" proved="true">
@@ -20,7 +20,7 @@
     <goal name="produces_trans&#39;vc.0.0.0" expl="VC for produces_trans" proved="true">
     <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
      <goal name="produces_trans&#39;vc.0.0.0.0" expl="VC for produces_trans" proved="true">
-     <proof prover="2"><result status="valid" time="0.020363" steps="218"/></proof>
+     <proof prover="0"><result status="valid" time="0.020363" steps="217"/></proof>
      </goal>
     </transf>
     </goal>
@@ -33,18 +33,18 @@
 </theory>
 <theory name="C10Once_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
- <proof prover="2"><result status="valid" time="0.010000" steps="95"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="95"/></proof>
  </goal>
 </theory>
 <theory name="C10Once_Impl0" proved="true">
  <goal name="produces_refl_refn" proved="true">
- <proof prover="2"><result status="valid" time="0.000000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="0"/></proof>
  </goal>
  <goal name="next_refn" proved="true">
- <proof prover="2"><result status="valid" time="0.010000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="0"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="2"><result status="valid" time="0.000000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/10_once/why3shapes.gz b/creusot/tests/should_succeed/iterators/10_once/why3shapes.gz
index a9dc0f9ff..996d94df3 100644
Binary files a/creusot/tests/should_succeed/iterators/10_once/why3shapes.gz and b/creusot/tests/should_succeed/iterators/10_once/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/11_repeat/why3session.xml b/creusot/tests/should_succeed/iterators/11_repeat/why3session.xml
index b959ae478..4559255de 100644
--- a/creusot/tests/should_succeed/iterators/11_repeat/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/11_repeat/why3session.xml
@@ -2,33 +2,33 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="11_repeat.mlcfg"/>
 <theory name="C11Repeat_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="10"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="10"/></proof>
  </goal>
 </theory>
 <theory name="C11Repeat_Impl0_ProducesTrans_Impl" proved="true">
  <goal name="produces_trans&#39;vc" expl="VC for produces_trans" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="67"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="67"/></proof>
  </goal>
 </theory>
 <theory name="C11Repeat_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="68"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="68"/></proof>
  </goal>
 </theory>
 <theory name="C11Repeat_Impl0" proved="true">
  <goal name="produces_trans_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="0"/></proof>
  </goal>
  <goal name="produces_refl_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="0"/></proof>
  </goal>
  <goal name="next_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/11_repeat/why3shapes.gz b/creusot/tests/should_succeed/iterators/11_repeat/why3shapes.gz
index e787d5c31..b651106bf 100644
Binary files a/creusot/tests/should_succeed/iterators/11_repeat/why3shapes.gz and b/creusot/tests/should_succeed/iterators/11_repeat/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/12_zip/why3session.xml b/creusot/tests/should_succeed/iterators/12_zip/why3session.xml
index 625fd2bdd..24abbb018 100644
--- a/creusot/tests/should_succeed/iterators/12_zip/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/12_zip/why3session.xml
@@ -2,13 +2,13 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="CVC4" version="1.8" timelimit="5" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="CVC5" version="1.0.5" timelimit="5" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="12_zip.mlcfg"/>
 <theory name="C12Zip_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="1" timelimit="5" memlimit="2000"><result status="valid" time="0.017139" steps="266"/></proof>
+ <proof prover="2" timelimit="5" memlimit="2000"><result status="valid" time="0.017139" steps="266"/></proof>
  </goal>
 </theory>
 <theory name="C12Zip_Impl0_ProducesTrans_Impl" proved="true">
@@ -31,25 +31,25 @@
          <goal name="produces_trans&#39;vc.0.0.0.0.0.0.0.0" proved="true">
          <transf name="split_vc" proved="true" >
           <goal name="produces_trans&#39;vc.0.0.0.0.0.0.0.0.0" proved="true">
-          <proof prover="1"><result status="valid" time="0.015861" steps="36"/></proof>
+          <proof prover="2"><result status="valid" time="0.015861" steps="36"/></proof>
           </goal>
           <goal name="produces_trans&#39;vc.0.0.0.0.0.0.0.0.1" proved="true">
-          <proof prover="1"><result status="valid" time="0.017509" steps="36"/></proof>
+          <proof prover="2"><result status="valid" time="0.017509" steps="36"/></proof>
           </goal>
           <goal name="produces_trans&#39;vc.0.0.0.0.0.0.0.0.2" proved="true">
-          <proof prover="1"><result status="valid" time="0.021981" steps="41"/></proof>
+          <proof prover="2"><result status="valid" time="0.021981" steps="39"/></proof>
           </goal>
           <goal name="produces_trans&#39;vc.0.0.0.0.0.0.0.0.3" proved="true">
-          <proof prover="1"><result status="valid" time="0.017642" steps="41"/></proof>
+          <proof prover="2"><result status="valid" time="0.017642" steps="39"/></proof>
           </goal>
           <goal name="produces_trans&#39;vc.0.0.0.0.0.0.0.0.4" proved="true">
-          <proof prover="1"><result status="valid" time="0.046172" steps="249"/></proof>
+          <proof prover="2"><result status="valid" time="0.046172" steps="249"/></proof>
           </goal>
           <goal name="produces_trans&#39;vc.0.0.0.0.0.0.0.0.5" proved="true">
-          <proof prover="1"><result status="valid" time="0.030815" steps="95"/></proof>
+          <proof prover="2"><result status="valid" time="0.030815" steps="95"/></proof>
           </goal>
           <goal name="produces_trans&#39;vc.0.0.0.0.0.0.0.0.6" proved="true">
-          <proof prover="1"><result status="valid" time="0.028920" steps="94"/></proof>
+          <proof prover="2"><result status="valid" time="0.028920" steps="94"/></proof>
           </goal>
          </transf>
          </goal>
@@ -72,18 +72,18 @@
 </theory>
 <theory name="C12Zip_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
- <proof prover="0"><result status="valid" time="0.260000" steps="68939"/></proof>
+ <proof prover="1"><result status="valid" time="0.083699" steps="43383"/></proof>
  </goal>
 </theory>
 <theory name="C12Zip_Impl0" proved="true">
  <goal name="produces_refl_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.020000" steps="7601"/></proof>
+ <proof prover="1"><result status="valid" time="0.011459" steps="4740"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.020000" steps="7601"/></proof>
+ <proof prover="1"><result status="valid" time="0.010882" steps="4740"/></proof>
  </goal>
  <goal name="next_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.030000" steps="7601"/></proof>
+ <proof prover="1"><result status="valid" time="0.010281" steps="4740"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/12_zip/why3shapes.gz b/creusot/tests/should_succeed/iterators/12_zip/why3shapes.gz
index ddf925bd5..289137742 100644
Binary files a/creusot/tests/should_succeed/iterators/12_zip/why3shapes.gz and b/creusot/tests/should_succeed/iterators/12_zip/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/13_cloned/why3session.xml b/creusot/tests/should_succeed/iterators/13_cloned/why3session.xml
index bec43bdf8..273f287cb 100644
--- a/creusot/tests/should_succeed/iterators/13_cloned/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/13_cloned/why3session.xml
@@ -2,33 +2,33 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="13_cloned.mlcfg"/>
 <theory name="C13Cloned_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="21"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="20"/></proof>
  </goal>
 </theory>
 <theory name="C13Cloned_Impl0_ProducesTrans_Impl" proved="true">
  <goal name="produces_trans&#39;vc" expl="VC for produces_trans" proved="true">
- <proof prover="1"><result status="valid" time="0.030000" steps="165"/></proof>
+ <proof prover="0"><result status="valid" time="0.030000" steps="165"/></proof>
  </goal>
 </theory>
 <theory name="C13Cloned_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
- <proof prover="1"><result status="valid" time="0.020000" steps="185"/></proof>
+ <proof prover="0"><result status="valid" time="0.020000" steps="185"/></proof>
  </goal>
 </theory>
 <theory name="C13Cloned_Impl0" proved="true">
  <goal name="next_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="0"/></proof>
  </goal>
  <goal name="produces_refl_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="0"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/13_cloned/why3shapes.gz b/creusot/tests/should_succeed/iterators/13_cloned/why3shapes.gz
index 67a078ee9..f6d3269db 100644
Binary files a/creusot/tests/should_succeed/iterators/13_cloned/why3shapes.gz and b/creusot/tests/should_succeed/iterators/13_cloned/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/14_copied/why3session.xml b/creusot/tests/should_succeed/iterators/14_copied/why3session.xml
index 7f3b4dac9..ec701e690 100644
--- a/creusot/tests/should_succeed/iterators/14_copied/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/14_copied/why3session.xml
@@ -2,33 +2,33 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="14_copied.mlcfg"/>
 <theory name="C14Copied_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="21"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="20"/></proof>
  </goal>
 </theory>
 <theory name="C14Copied_Impl0_ProducesTrans_Impl" proved="true">
  <goal name="produces_trans&#39;vc" expl="VC for produces_trans" proved="true">
- <proof prover="1"><result status="valid" time="0.040000" steps="165"/></proof>
+ <proof prover="0"><result status="valid" time="0.040000" steps="165"/></proof>
  </goal>
 </theory>
 <theory name="C14Copied_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
- <proof prover="1"><result status="valid" time="0.020000" steps="185"/></proof>
+ <proof prover="0"><result status="valid" time="0.020000" steps="185"/></proof>
  </goal>
 </theory>
 <theory name="C14Copied_Impl0" proved="true">
  <goal name="next_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="0"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.000000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="0"/></proof>
  </goal>
  <goal name="produces_refl_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="1"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/14_copied/why3shapes.gz b/creusot/tests/should_succeed/iterators/14_copied/why3shapes.gz
index f54c3e28b..5e972159e 100644
Binary files a/creusot/tests/should_succeed/iterators/14_copied/why3shapes.gz and b/creusot/tests/should_succeed/iterators/14_copied/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/15_enumerate/why3session.xml b/creusot/tests/should_succeed/iterators/15_enumerate/why3session.xml
index 23178b610..b1dc56c17 100644
--- a/creusot/tests/should_succeed/iterators/15_enumerate/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/15_enumerate/why3session.xml
@@ -2,67 +2,67 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="15_enumerate.mlcfg"/>
 <theory name="C15Enumerate_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="37"/></proof>
+ <proof prover="3"><result status="valid" time="0.010000" steps="37"/></proof>
  </goal>
 </theory>
 <theory name="C15Enumerate_Impl0_ProducesTrans_Impl" proved="true">
  <goal name="produces_trans&#39;vc" expl="VC for produces_trans" proved="true">
- <proof prover="0"><result status="valid" time="0.110000" steps="489"/></proof>
+ <proof prover="3"><result status="valid" time="0.110000" steps="488"/></proof>
  </goal>
 </theory>
 <theory name="C15Enumerate_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="next&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.014107" steps="19"/></proof>
+  <proof prover="3"><result status="valid" time="0.014107" steps="18"/></proof>
   </goal>
   <goal name="next&#39;vc.1" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.010370" steps="19"/></proof>
+  <proof prover="3"><result status="valid" time="0.010370" steps="18"/></proof>
   </goal>
   <goal name="next&#39;vc.2" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.013290" steps="196"/></proof>
+  <proof prover="3"><result status="valid" time="0.013290" steps="196"/></proof>
   </goal>
   <goal name="next&#39;vc.3" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.041672" steps="29"/></proof>
+  <proof prover="3"><result status="valid" time="0.041672" steps="28"/></proof>
   </goal>
   <goal name="next&#39;vc.4" expl="integer overflow" proved="true">
-  <proof prover="0"><result status="valid" time="0.047851" steps="242"/></proof>
+  <proof prover="3"><result status="valid" time="0.047851" steps="241"/></proof>
   </goal>
   <goal name="next&#39;vc.5" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.014076" steps="624"/></proof>
+  <proof prover="3"><result status="valid" time="0.014076" steps="623"/></proof>
   </goal>
   <goal name="next&#39;vc.6" expl="unreachable point" proved="true">
-  <proof prover="0"><result status="valid" time="0.016682" steps="28"/></proof>
+  <proof prover="3"><result status="valid" time="0.016682" steps="28"/></proof>
   </goal>
   <goal name="next&#39;vc.7" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.076662" steps="296815"/></proof>
+  <proof prover="2"><result status="valid" time="0.076662" steps="235572"/></proof>
   </goal>
   <goal name="next&#39;vc.8" expl="postcondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.017161" steps="10"/></proof>
+  <proof prover="3"><result status="valid" time="0.017161" steps="10"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="C15Enumerate_Enumerate" proved="true">
  <goal name="enumerate&#39;vc" expl="VC for enumerate" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="88"/></proof>
+ <proof prover="3"><result status="valid" time="0.010000" steps="88"/></proof>
  </goal>
 </theory>
 <theory name="C15Enumerate_Impl0" proved="true">
  <goal name="next_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="3"/></proof>
+ <proof prover="3"><result status="valid" time="0.010000" steps="2"/></proof>
  </goal>
  <goal name="produces_refl_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="3"/></proof>
+ <proof prover="3"><result status="valid" time="0.010000" steps="2"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="3"/></proof>
+ <proof prover="3"><result status="valid" time="0.010000" steps="2"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/15_enumerate/why3shapes.gz b/creusot/tests/should_succeed/iterators/15_enumerate/why3shapes.gz
index a7cee1ca1..f356beaf7 100644
Binary files a/creusot/tests/should_succeed/iterators/15_enumerate/why3shapes.gz and b/creusot/tests/should_succeed/iterators/15_enumerate/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/iterators/16_take/why3session.xml b/creusot/tests/should_succeed/iterators/16_take/why3session.xml
index ca91def84..df447a949 100644
--- a/creusot/tests/should_succeed/iterators/16_take/why3session.xml
+++ b/creusot/tests/should_succeed/iterators/16_take/why3session.xml
@@ -2,34 +2,33 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="16_take.mlcfg"/>
 <theory name="C16Take_Impl0_ProducesRefl_Impl" proved="true">
  <goal name="produces_refl&#39;vc" expl="VC for produces_refl" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="17"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="17"/></proof>
  </goal>
 </theory>
 <theory name="C16Take_Impl0_ProducesTrans_Impl" proved="true">
  <goal name="produces_trans&#39;vc" expl="VC for produces_trans" proved="true">
- <proof prover="1"><result status="valid" time="0.010000" steps="92"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="92"/></proof>
  </goal>
 </theory>
 <theory name="C16Take_Impl0_Next" proved="true">
  <goal name="next&#39;vc" expl="VC for next" proved="true">
- <proof prover="1"><result status="valid" time="0.080000" steps="756"/></proof>
+ <proof prover="0"><result status="valid" time="0.080000" steps="755"/></proof>
  </goal>
 </theory>
 <theory name="C16Take_Impl0" proved="true">
  <goal name="next_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="3"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="2"/></proof>
  </goal>
  <goal name="produces_refl_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.010000" steps="3"/></proof>
+ <proof prover="0"><result status="valid" time="0.010000" steps="2"/></proof>
  </goal>
  <goal name="produces_trans_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.000000" steps="3"/></proof>
+ <proof prover="0"><result status="valid" time="0.000000" steps="2"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/iterators/16_take/why3shapes.gz b/creusot/tests/should_succeed/iterators/16_take/why3shapes.gz
index d1e1dccf8..d6461803a 100644
Binary files a/creusot/tests/should_succeed/iterators/16_take/why3shapes.gz and b/creusot/tests/should_succeed/iterators/16_take/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/knapsack/why3session.xml b/creusot/tests/should_succeed/knapsack/why3session.xml
index 27f9bc085..de3fbe681 100644
--- a/creusot/tests/should_succeed/knapsack/why3session.xml
+++ b/creusot/tests/should_succeed/knapsack/why3session.xml
@@ -2,293 +2,292 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="4" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="knapsack.mlcfg"/>
 <theory name="Knapsack_Max" proved="true">
  <goal name="max&#39;vc" expl="VC for max" proved="true">
- <proof prover="0"><result status="valid" time="0.008930" steps="1931"/></proof>
+ <proof prover="3"><result status="valid" time="0.010475" steps="1914"/></proof>
  </goal>
 </theory>
 <theory name="Knapsack_M_Impl" proved="true">
  <goal name="m&#39;vc" expl="VC for m" proved="true">
- <proof prover="2"><result status="valid" time="0.011091" steps="98"/></proof>
+ <proof prover="4"><result status="valid" time="0.011091" steps="97"/></proof>
  </goal>
 </theory>
 <theory name="Knapsack_Knapsack01Dyn" proved="true">
  <goal name="knapsack01_dyn&#39;vc" expl="VC for knapsack01_dyn" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="knapsack01_dyn&#39;vc.0" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.020427" steps="14"/></proof>
+  <proof prover="4"><result status="valid" time="0.020427" steps="13"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.023131" steps="21"/></proof>
+  <proof prover="4"><result status="valid" time="0.023131" steps="21"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.022499" steps="17"/></proof>
+  <proof prover="4"><result status="valid" time="0.022499" steps="16"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.3" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.022645" steps="40"/></proof>
+  <proof prover="4"><result status="valid" time="0.022645" steps="38"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.020366" steps="22"/></proof>
+  <proof prover="4"><result status="valid" time="0.020366" steps="22"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.5" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.017301" steps="27"/></proof>
+  <proof prover="4"><result status="valid" time="0.017301" steps="26"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.6" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.023566" steps="49"/></proof>
+  <proof prover="4"><result status="valid" time="0.023566" steps="49"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.7" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.042198" steps="288"/></proof>
+  <proof prover="4"><result status="valid" time="0.042198" steps="288"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.8" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.040132" steps="213"/></proof>
+  <proof prover="4"><result status="valid" time="0.040132" steps="213"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.017682" steps="30"/></proof>
+  <proof prover="4"><result status="valid" time="0.017682" steps="30"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.022531" steps="34"/></proof>
+  <proof prover="4"><result status="valid" time="0.022531" steps="33"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.019176" steps="35"/></proof>
+  <proof prover="4"><result status="valid" time="0.019176" steps="34"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.12" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.026751" steps="62"/></proof>
+  <proof prover="4"><result status="valid" time="0.026751" steps="62"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.13" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.019397" steps="38"/></proof>
+  <proof prover="4"><result status="valid" time="0.019397" steps="38"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.14" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.020045" steps="42"/></proof>
+  <proof prover="4"><result status="valid" time="0.020045" steps="42"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.15" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.024306" steps="71"/></proof>
+  <proof prover="4"><result status="valid" time="0.024306" steps="70"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.16" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.024895" steps="79"/></proof>
+  <proof prover="4"><result status="valid" time="0.024895" steps="79"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.17" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.019866" steps="44"/></proof>
+  <proof prover="4"><result status="valid" time="0.019866" steps="44"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.18" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.022787" steps="79"/></proof>
+  <proof prover="4"><result status="valid" time="0.022787" steps="79"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.19" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.020836" steps="48"/></proof>
+  <proof prover="4"><result status="valid" time="0.020836" steps="48"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.20" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.020111" steps="88"/></proof>
+  <proof prover="4"><result status="valid" time="0.020111" steps="88"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.21" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.026337" steps="89"/></proof>
+  <proof prover="4"><result status="valid" time="0.026337" steps="89"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.22" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.026965" steps="112"/></proof>
+  <proof prover="4"><result status="valid" time="0.026965" steps="111"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.23" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.012706" steps="54"/></proof>
+  <proof prover="4"><result status="valid" time="0.012706" steps="54"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.24" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.035472" steps="97"/></proof>
+  <proof prover="4"><result status="valid" time="0.035472" steps="96"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.25" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.020741" steps="48"/></proof>
+  <proof prover="4"><result status="valid" time="0.020741" steps="48"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.26" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.025908" steps="88"/></proof>
+  <proof prover="4"><result status="valid" time="0.025908" steps="88"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.27" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.026494" steps="89"/></proof>
+  <proof prover="4"><result status="valid" time="0.026494" steps="89"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.28" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.039702" steps="112"/></proof>
+  <proof prover="4"><result status="valid" time="0.039702" steps="111"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.29" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.020592" steps="54"/></proof>
+  <proof prover="4"><result status="valid" time="0.020592" steps="54"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.30" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.027397" steps="97"/></proof>
+  <proof prover="4"><result status="valid" time="0.027397" steps="96"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.31" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.018233" steps="56"/></proof>
+  <proof prover="4"><result status="valid" time="0.018233" steps="56"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.32" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.026388" steps="100"/></proof>
+  <proof prover="4"><result status="valid" time="0.026388" steps="99"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.33" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.025912" steps="102"/></proof>
+  <proof prover="4"><result status="valid" time="0.025912" steps="101"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.34" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.033490" steps="135"/></proof>
+  <proof prover="4"><result status="valid" time="0.033490" steps="134"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.35" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.029768" steps="147"/></proof>
+  <proof prover="4"><result status="valid" time="0.029768" steps="146"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.36" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.022048" steps="63"/></proof>
+  <proof prover="4"><result status="valid" time="0.022048" steps="63"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.37" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.024569" steps="125"/></proof>
+  <proof prover="4"><result status="valid" time="0.024569" steps="124"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.38" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.130652" steps="974"/></proof>
+  <proof prover="4"><result status="valid" time="0.130652" steps="973"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.39" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.023774" steps="65"/></proof>
+  <proof prover="4"><result status="valid" time="0.023774" steps="65"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.40" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.023690" steps="46"/></proof>
+  <proof prover="4"><result status="valid" time="0.023690" steps="46"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.41" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.029496" steps="92"/></proof>
+  <proof prover="4"><result status="valid" time="0.029496" steps="91"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.42" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.023540" steps="50"/></proof>
+  <proof prover="4"><result status="valid" time="0.023540" steps="50"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.43" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.019478" steps="95"/></proof>
+  <proof prover="4"><result status="valid" time="0.019478" steps="94"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.44" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.048129" steps="225"/></proof>
+  <proof prover="4"><result status="valid" time="0.048129" steps="225"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.45" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.033652" steps="106"/></proof>
+  <proof prover="4"><result status="valid" time="0.033652" steps="105"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.46" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.029254" steps="117"/></proof>
+  <proof prover="4"><result status="valid" time="0.029254" steps="116"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.47" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.038399" steps="121"/></proof>
+  <proof prover="4"><result status="valid" time="0.038399" steps="120"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.48" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.033556" steps="115"/></proof>
+  <proof prover="4"><result status="valid" time="0.033556" steps="113"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.49" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.033104" steps="115"/></proof>
+  <proof prover="4"><result status="valid" time="0.033104" steps="115"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.50" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.069697" steps="334"/></proof>
+  <proof prover="4"><result status="valid" time="0.069697" steps="334"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.51" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.047138" steps="136"/></proof>
+  <proof prover="4"><result status="valid" time="0.047138" steps="135"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.52" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.046144" steps="135"/></proof>
+  <proof prover="4"><result status="valid" time="0.046144" steps="135"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.53" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.050868" steps="166"/></proof>
+  <proof prover="4"><result status="valid" time="0.050868" steps="165"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.54" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.043021" steps="169"/></proof>
+  <proof prover="4"><result status="valid" time="0.043021" steps="169"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.55" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.093551" steps="557"/></proof>
+  <proof prover="4"><result status="valid" time="0.093551" steps="556"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.56" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.107541" steps="671"/></proof>
+  <proof prover="4"><result status="valid" time="0.107541" steps="670"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.57" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.064285" steps="178422"/></proof>
+  <proof prover="3"><result status="valid" time="0.064285" steps="177831"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.58" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.092984" steps="182340"/></proof>
+  <proof prover="3"><result status="valid" time="0.092984" steps="179242"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.59" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.020645" steps="34"/></proof>
+  <proof prover="4"><result status="valid" time="0.020645" steps="33"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.60" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.015659" steps="43"/></proof>
+  <proof prover="4"><result status="valid" time="0.015659" steps="41"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.61" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.020432" steps="47"/></proof>
+  <proof prover="4"><result status="valid" time="0.020432" steps="46"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.62" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.019735" steps="47"/></proof>
+  <proof prover="4"><result status="valid" time="0.019735" steps="47"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.63" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.030984" steps="101"/></proof>
+  <proof prover="4"><result status="valid" time="0.030984" steps="100"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.64" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.017439" steps="54"/></proof>
+  <proof prover="4"><result status="valid" time="0.017439" steps="53"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.65" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.026964" steps="54"/></proof>
+  <proof prover="4"><result status="valid" time="0.026964" steps="53"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.66" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.040180" steps="115"/></proof>
+  <proof prover="4"><result status="valid" time="0.040180" steps="113"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.67" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.026674" steps="56"/></proof>
+  <proof prover="4"><result status="valid" time="0.026674" steps="56"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.68" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.043037" steps="120"/></proof>
+  <proof prover="4"><result status="valid" time="0.043037" steps="119"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.69" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.019928" steps="62"/></proof>
+  <proof prover="4"><result status="valid" time="0.019928" steps="61"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.70" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.030725" steps="130"/></proof>
+  <proof prover="4"><result status="valid" time="0.030725" steps="130"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.71" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.051895" steps="131"/></proof>
+  <proof prover="4"><result status="valid" time="0.051895" steps="130"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.72" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.046918" steps="160"/></proof>
+  <proof prover="4"><result status="valid" time="0.046918" steps="159"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.73" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.024108" steps="66"/></proof>
+  <proof prover="4"><result status="valid" time="0.024108" steps="66"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.74" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.047239" steps="141"/></proof>
+  <proof prover="4"><result status="valid" time="0.047239" steps="140"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.75" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.027626" steps="68"/></proof>
+  <proof prover="4"><result status="valid" time="0.027626" steps="68"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.76" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.031431" steps="147"/></proof>
+  <proof prover="4"><result status="valid" time="0.031431" steps="145"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.77" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.037557" steps="148"/></proof>
+  <proof prover="4"><result status="valid" time="0.037557" steps="147"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.78" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.034108" steps="176"/></proof>
+  <proof prover="4"><result status="valid" time="0.034108" steps="176"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.79" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.031362" steps="74"/></proof>
+  <proof prover="4"><result status="valid" time="0.031362" steps="74"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.80" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.036570" steps="155"/></proof>
+  <proof prover="4"><result status="valid" time="0.036570" steps="154"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.81" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.026172" steps="78"/></proof>
+  <proof prover="4"><result status="valid" time="0.026172" steps="78"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.82" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.036448" steps="196"/></proof>
+  <proof prover="4"><result status="valid" time="0.036448" steps="194"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.83" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.017651" steps="84"/></proof>
+  <proof prover="4"><result status="valid" time="0.017651" steps="84"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.84" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.022945" steps="84"/></proof>
+  <proof prover="4"><result status="valid" time="0.022945" steps="84"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.85" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.628739" steps="3857"/></proof>
+  <proof prover="4"><result status="valid" time="0.280775" steps="3857"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.86" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.016321" steps="51"/></proof>
+  <proof prover="4"><result status="valid" time="0.016321" steps="50"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.87" expl="postcondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.030949" steps="106"/></proof>
+  <proof prover="4"><result status="valid" time="0.030949" steps="105"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.88" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.018116" steps="78"/></proof>
+  <proof prover="4"><result status="valid" time="0.018116" steps="78"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.89" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.047101" steps="292"/></proof>
+  <proof prover="4"><result status="valid" time="0.047101" steps="291"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/knapsack/why3shapes.gz b/creusot/tests/should_succeed/knapsack/why3shapes.gz
index f23922353..50912efcb 100644
Binary files a/creusot/tests/should_succeed/knapsack/why3shapes.gz and b/creusot/tests/should_succeed/knapsack/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/knapsack_full/why3session.xml b/creusot/tests/should_succeed/knapsack_full/why3session.xml
index 83eeaddb4..f8985689c 100644
--- a/creusot/tests/should_succeed/knapsack_full/why3session.xml
+++ b/creusot/tests/should_succeed/knapsack_full/why3session.xml
@@ -3,383 +3,382 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="2" name="CVC4" version="1.8" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="3" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="5" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<file format="mlcfg" proved="true">
+<prover id="4" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="6" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
+<file format="mlcfg">
 <path name=".."/><path name="knapsack_full.mlcfg"/>
 <theory name="KnapsackFull_Max" proved="true">
  <goal name="max&#39;vc" expl="VC for max" proved="true">
- <proof prover="1"><result status="valid" time="0.008016" steps="1931"/></proof>
+ <proof prover="4"><result status="valid" time="0.008841" steps="1914"/></proof>
  </goal>
 </theory>
 <theory name="KnapsackFull_SumWeights_Impl" proved="true">
  <goal name="sum_weights&#39;vc" expl="VC for sum_weights" proved="true">
- <proof prover="0"><result status="valid" time="0.057561" steps="8320"/></proof>
+ <proof prover="0"><result status="valid" time="0.057561" steps="8050"/></proof>
  </goal>
 </theory>
 <theory name="KnapsackFull_SumValues_Impl" proved="true">
  <goal name="sum_values&#39;vc" expl="VC for sum_values" proved="true">
- <proof prover="5"><result status="valid" time="0.008662" steps="12"/></proof>
+ <proof prover="6"><result status="valid" time="0.008662" steps="12"/></proof>
  </goal>
 </theory>
 <theory name="KnapsackFull_SubseqRev_Impl" proved="true">
  <goal name="subseq_rev&#39;vc" expl="VC for subseq_rev" proved="true">
- <proof prover="1"><result status="valid" time="0.015740" steps="44485"/></proof>
+ <proof prover="4"><result status="valid" time="0.015920" steps="42227"/></proof>
  </goal>
 </theory>
 <theory name="KnapsackFull_M_Impl" proved="true">
  <goal name="m&#39;vc" expl="VC for m" proved="true">
- <proof prover="3"><result status="valid" time="0.019525" steps="73450"/></proof>
+ <proof prover="4"><result status="valid" time="0.019525" steps="70361"/></proof>
  </goal>
 </theory>
-<theory name="KnapsackFull_Knapsack01Dyn" proved="true">
- <goal name="knapsack01_dyn&#39;vc" expl="VC for knapsack01_dyn" proved="true">
- <transf name="split_vc" proved="true" >
+<theory name="KnapsackFull_Knapsack01Dyn">
+ <goal name="knapsack01_dyn&#39;vc" expl="VC for knapsack01_dyn">
+ <transf name="split_vc" >
   <goal name="knapsack01_dyn&#39;vc.0" expl="integer overflow" proved="true">
-  <proof prover="5"><result status="valid" time="0.011401" steps="14"/></proof>
+  <proof prover="6"><result status="valid" time="0.011401" steps="14"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.014143" steps="22"/></proof>
+  <proof prover="6"><result status="valid" time="0.014143" steps="22"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.020097" steps="16"/></proof>
+  <proof prover="6"><result status="valid" time="0.020097" steps="16"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.3" expl="integer overflow" proved="true">
-  <proof prover="5"><result status="valid" time="0.012163" steps="40"/></proof>
+  <proof prover="6"><result status="valid" time="0.012163" steps="40"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.017609" steps="22"/></proof>
+  <proof prover="6"><result status="valid" time="0.017609" steps="22"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.039289" steps="11985"/></proof>
+  <proof prover="4"><result status="valid" time="0.012444" steps="12658"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.011043" steps="29"/></proof>
+  <proof prover="6"><result status="valid" time="0.011043" steps="29"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.014713" steps="53"/></proof>
+  <proof prover="6"><result status="valid" time="0.014713" steps="53"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.8" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.011373" steps="12342"/></proof>
+  <proof prover="4"><result status="valid" time="0.012712" steps="13015"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.9" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.013632" steps="65"/></proof>
+  <proof prover="6"><result status="valid" time="0.013632" steps="65"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.10" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.011336" steps="36"/></proof>
+  <proof prover="6"><result status="valid" time="0.011336" steps="36"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.11" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.013452" steps="70"/></proof>
+  <proof prover="6"><result status="valid" time="0.013452" steps="70"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.12" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.024395" steps="342"/></proof>
+  <proof prover="6"><result status="valid" time="0.024395" steps="342"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.13" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.018805" steps="172"/></proof>
+  <proof prover="6"><result status="valid" time="0.018805" steps="172"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.016312" steps="75"/></proof>
+  <proof prover="6"><result status="valid" time="0.016312" steps="75"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.046646" steps="12704"/></proof>
+  <proof prover="4"><result status="valid" time="0.013598" steps="13375"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.015268" steps="62"/></proof>
+  <proof prover="6"><result status="valid" time="0.015268" steps="62"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.17" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.012700" steps="64"/></proof>
+  <proof prover="6"><result status="valid" time="0.012700" steps="64"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.18" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.012375" steps="65"/></proof>
+  <proof prover="6"><result status="valid" time="0.012375" steps="65"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.19" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.012916" steps="72"/></proof>
+  <proof prover="6"><result status="valid" time="0.012916" steps="72"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.20" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.019851" steps="101365"/></proof>
+  <proof prover="4"><result status="valid" time="0.022066" steps="86809"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.21" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.013177" steps="72"/></proof>
+  <proof prover="6"><result status="valid" time="0.013177" steps="72"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.22" expl="integer overflow" proved="true">
-  <proof prover="5"><result status="valid" time="0.016048" steps="115"/></proof>
+  <proof prover="6"><result status="valid" time="0.016048" steps="115"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.23" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.013470" steps="72"/></proof>
+  <proof prover="6"><result status="valid" time="0.013470" steps="72"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.24" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.053563" steps="73"/></proof>
+  <proof prover="6"><result status="valid" time="0.053563" steps="73"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.25" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.017476" steps="127"/></proof>
+  <proof prover="6"><result status="valid" time="0.017476" steps="127"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.26" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.013722" steps="78"/></proof>
+  <proof prover="6"><result status="valid" time="0.013722" steps="78"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.27" expl="integer overflow" proved="true">
-  <proof prover="5"><result status="valid" time="0.016336" steps="132"/></proof>
+  <proof prover="6"><result status="valid" time="0.016336" steps="132"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.28" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.013380" steps="82"/></proof>
+  <proof prover="6"><result status="valid" time="0.013380" steps="82"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.29" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.014239" steps="143"/></proof>
+  <proof prover="6"><result status="valid" time="0.014239" steps="143"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.30" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.032819" steps="193436"/></proof>
+  <proof prover="4"><result status="valid" time="0.034141" steps="179591"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.31" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.018504" steps="161"/></proof>
+  <proof prover="6"><result status="valid" time="0.018504" steps="181"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.32" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.011539" steps="13239"/></proof>
+  <proof prover="4"><result status="valid" time="0.014097" steps="13910"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.33" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.018515" steps="153"/></proof>
+  <proof prover="6"><result status="valid" time="0.018515" steps="153"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.34" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.013700" steps="90"/></proof>
+  <proof prover="6"><result status="valid" time="0.013700" steps="90"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.35" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.012814" steps="160"/></proof>
+  <proof prover="6"><result status="valid" time="0.012814" steps="160"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.36" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.031382" steps="193983"/></proof>
+  <proof prover="4"><result status="valid" time="0.034240" steps="180102"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.37" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.019570" steps="175"/></proof>
+  <proof prover="6"><result status="valid" time="0.019570" steps="195"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.38" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.021841" steps="96"/></proof>
+  <proof prover="6"><result status="valid" time="0.021841" steps="96"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.39" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.036002" steps="194257"/></proof>
+  <proof prover="4"><result status="valid" time="0.034266" steps="180359"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.40" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.014931" steps="100"/></proof>
+  <proof prover="6"><result status="valid" time="0.014931" steps="100"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.41" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.014302" steps="209"/></proof>
+  <proof prover="6"><result status="valid" time="0.014302" steps="209"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.42" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.024479" steps="105244"/></proof>
+  <proof prover="4"><result status="valid" time="0.018274" steps="48958"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.43" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.025140" steps="108"/></proof>
+  <proof prover="6"><result status="valid" time="0.025140" steps="108"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.44" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.113641" steps="619031"/></proof>
+  <proof prover="4"><result status="valid" time="0.145125" steps="700251"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.45" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.017596" steps="72"/></proof>
+  <proof prover="6"><result status="valid" time="0.017596" steps="72"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.46" expl="postcondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.061701" steps="703"/></proof>
+  <proof prover="6"><result status="valid" time="0.061701" steps="706"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.47" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.177099" steps="440283"/></proof>
+  <proof prover="4"><result status="valid" time="0.078676" steps="402522"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.48" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.035419" steps="195734"/></proof>
+  <proof prover="4"><result status="valid" time="0.034538" steps="181801"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.49" expl="postcondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.036480" steps="128"/></proof>
+  <proof prover="6"><result status="valid" time="0.036480" steps="131"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.50" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.020488" steps="100"/></proof>
+  <proof prover="6"><result status="valid" time="0.020488" steps="100"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.51" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.024641" steps="318"/></proof>
+  <proof prover="6"><result status="valid" time="0.024641" steps="319"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.52" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.398416" steps="2195538"/></proof>
+  <proof prover="4"><result status="valid" time="0.181208" steps="821109"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.53" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.222101" steps="1356796"/></proof>
+  <proof prover="4"><result status="valid" time="0.133621" steps="626636"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.54" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.474101" steps="1882707"/></proof>
+  <proof prover="4"><result status="valid" time="0.295033" steps="1212048"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.55" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.032376" steps="514"/></proof>
+  <proof prover="6"><result status="valid" time="0.032376" steps="516"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.56" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.039703" steps="12789"/></proof>
+  <proof prover="4"><result status="valid" time="0.013403" steps="13460"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.57" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.011525" steps="180822"/></proof>
+  <proof prover="4"><result status="valid" time="0.032934" steps="167277"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.58" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.014203" steps="72"/></proof>
+  <proof prover="6"><result status="valid" time="0.014203" steps="72"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.59" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.017854" steps="104"/></proof>
+  <proof prover="6"><result status="valid" time="0.017854" steps="104"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.60" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.016999" steps="105"/></proof>
+  <proof prover="6"><result status="valid" time="0.016999" steps="105"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.61" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.017854" steps="80"/></proof>
+  <proof prover="6"><result status="valid" time="0.017854" steps="80"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.62" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.011820" steps="80"/></proof>
+  <proof prover="6"><result status="valid" time="0.011820" steps="80"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.63" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.010875" steps="13083"/></proof>
+  <proof prover="4"><result status="valid" time="0.013758" steps="13754"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.64" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.016613" steps="128"/></proof>
+  <proof prover="6"><result status="valid" time="0.016613" steps="128"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.65" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.011486" steps="12943"/></proof>
+  <proof prover="4"><result status="valid" time="0.014170" steps="13614"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.66" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.016992" steps="126"/></proof>
+  <proof prover="6"><result status="valid" time="0.016992" steps="126"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.67" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.049417" steps="879"/></proof>
+  <proof prover="6"><result status="valid" time="0.049417" steps="898"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.68" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.018353" steps="150"/></proof>
+  <proof prover="6"><result status="valid" time="0.018353" steps="150"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.69" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.017460" steps="137"/></proof>
+  <proof prover="6"><result status="valid" time="0.017460" steps="137"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.70" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.033259" steps="132"/></proof>
+  <proof prover="6"><result status="valid" time="0.033259" steps="132"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.71" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.020043" steps="105900"/></proof>
+  <proof prover="4"><result status="valid" time="0.018851" steps="49482"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.72" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.040917" steps="196277"/></proof>
+  <proof prover="4"><result status="valid" time="0.035649" steps="182162"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.73" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.109595" steps="2269"/></proof>
+  <proof prover="6"><result status="valid" time="0.109595" steps="2308"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.74" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.026553" steps="113"/></proof>
+  <proof prover="6"><result status="valid" time="0.026553" steps="113"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.75" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.049064" steps="149"/></proof>
+  <proof prover="6"><result status="valid" time="0.049064" steps="149"/></proof>
   </goal>
-  <goal name="knapsack01_dyn&#39;vc.76" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.380115" steps="60380"/></proof>
+  <goal name="knapsack01_dyn&#39;vc.76" expl="loop invariant preservation">
+  <proof prover="2" obsolete="true"><result status="valid" time="0.380115" steps="60380"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.77" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.063604" steps="199054"/></proof>
+  <proof prover="4"><result status="valid" time="0.036400" steps="184710"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.78" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.163635" steps="1274"/></proof>
+  <proof prover="6"><result status="valid" time="0.163635" steps="1290"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.79" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.040623" steps="175"/></proof>
+  <proof prover="6"><result status="valid" time="0.040623" steps="175"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.80" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.072229" steps="194069"/></proof>
+  <proof prover="4"><result status="valid" time="0.035633" steps="179229"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.81" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.136087" steps="732994"/></proof>
+  <proof prover="4"><result status="valid" time="0.368817" steps="1298553"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.82" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.037611" steps="13703"/></proof>
+  <proof prover="4"><result status="valid" time="0.014478" steps="14382"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.83" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.037483" steps="194336"/></proof>
+  <proof prover="4"><result status="valid" time="0.035641" steps="179481"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.84" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.072129" steps="1278"/></proof>
+  <proof prover="6"><result status="valid" time="0.072129" steps="1290"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.85" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.033029" steps="175"/></proof>
+  <proof prover="6"><result status="valid" time="0.033029" steps="175"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.86" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.015952" steps="176"/></proof>
+  <proof prover="6"><result status="valid" time="0.015952" steps="176"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.87" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.140035" steps="732689"/></proof>
+  <proof prover="4"><result status="valid" time="0.362963" steps="1297677"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.88" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.107794" steps="22068"/></proof>
+  <proof prover="0"><result status="valid" time="0.107794" steps="21497"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.89" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.035215" steps="194283"/></proof>
+  <proof prover="4"><result status="valid" time="0.035901" steps="179434"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.90" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.041623" steps="207384"/></proof>
+  <proof prover="4"><result status="valid" time="0.042873" steps="209276"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.91" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.033009" steps="194517"/></proof>
+  <proof prover="4"><result status="valid" time="0.035028" steps="179657"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.92" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.022194" steps="189"/></proof>
+  <proof prover="6"><result status="valid" time="0.022194" steps="189"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.93" expl="integer overflow" proved="true">
-  <proof prover="5"><result status="valid" time="0.022286" steps="255"/></proof>
+  <proof prover="6"><result status="valid" time="0.022286" steps="255"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.94" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.144794" steps="728019"/></proof>
+  <proof prover="4"><result status="valid" time="0.393785" steps="1369407"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.95" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.015843" steps="136"/></proof>
+  <proof prover="6"><result status="valid" time="0.015843" steps="136"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.96" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.036658" steps="194954"/></proof>
+  <proof prover="4"><result status="valid" time="0.035417" steps="180058"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.97" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.139240" steps="729911"/></proof>
+  <proof prover="4"><result status="valid" time="0.359151" steps="1238012"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.98" expl="integer overflow" proved="true">
-  <proof prover="5"><result status="valid" time="0.070200" steps="919"/></proof>
+  <proof prover="6"><result status="valid" time="0.070200" steps="915"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.99" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.055707" steps="891"/></proof>
+  <proof prover="6"><result status="valid" time="0.055707" steps="903"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.100" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.014599" steps="157"/></proof>
+  <proof prover="6"><result status="valid" time="0.014599" steps="157"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.101" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.032589" steps="204080"/></proof>
+  <proof prover="4"><result status="valid" time="0.035299" steps="189195"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.102" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.136522" steps="747076"/></proof>
+  <proof prover="4"><result status="valid" time="0.328095" steps="1248990"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.103" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.066507" steps="184"/></proof>
+  <proof prover="6"><result status="valid" time="0.066507" steps="184"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.104" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.058942" steps="184"/></proof>
+  <proof prover="6"><result status="valid" time="0.058942" steps="184"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.105" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.128749" steps="26108"/></proof>
+  <proof prover="0"><result status="valid" time="0.128749" steps="25406"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.106" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.139440" steps="743051"/></proof>
+  <proof prover="4"><result status="valid" time="0.449653" steps="1529506"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.107" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.014586" steps="214"/></proof>
+  <proof prover="6"><result status="valid" time="0.014586" steps="214"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.108" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.060599" steps="978"/></proof>
+  <proof prover="6"><result status="valid" time="0.060599" steps="977"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.109" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.166346" steps="2966"/></proof>
+  <proof prover="6"><result status="valid" time="0.166346" steps="2956"/></proof>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.110" expl="loop invariant preservation" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="knapsack01_dyn&#39;vc.110.0" expl="loop invariant preservation" proved="true">
    <transf name="split_vc" proved="true" >
     <goal name="knapsack01_dyn&#39;vc.110.0.0" expl="loop invariant preservation" proved="true">
-    <proof prover="0"><result status="valid" time="0.676383" steps="97776"/></proof>
+    <proof prover="0"><result status="valid" time="0.423537" steps="96081"/></proof>
     </goal>
     <goal name="knapsack01_dyn&#39;vc.110.0.1" expl="loop invariant preservation" proved="true">
     <transf name="inline_goal" proved="true" >
      <goal name="knapsack01_dyn&#39;vc.110.0.1.0" expl="loop invariant preservation" proved="true">
      <transf name="split_all_full" proved="true" >
       <goal name="knapsack01_dyn&#39;vc.110.0.1.0.0" expl="loop invariant preservation" proved="true">
-      <proof prover="1" timelimit="30" memlimit="4000"><result status="valid" time="0.123057" steps="725381"/></proof>
+      <proof prover="4" timelimit="30" memlimit="4000"><result status="valid" time="1.111865" steps="3565311"/></proof>
       </goal>
      </transf>
      </goal>
@@ -390,7 +389,7 @@
   </transf>
   </goal>
   <goal name="knapsack01_dyn&#39;vc.111" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.720986" steps="73517"/></proof>
+  <proof prover="0"><result status="valid" time="0.289571" steps="68876"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/knapsack_full/why3shapes.gz b/creusot/tests/should_succeed/knapsack_full/why3shapes.gz
index a8c285a20..d2c69afb5 100644
Binary files a/creusot/tests/should_succeed/knapsack_full/why3shapes.gz and b/creusot/tests/should_succeed/knapsack_full/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/lang/modules/why3session.xml b/creusot/tests/should_succeed/lang/modules/why3session.xml
index f929acf6f..d4edf9a30 100644
--- a/creusot/tests/should_succeed/lang/modules/why3session.xml
+++ b/creusot/tests/should_succeed/lang/modules/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="modules.mlcfg"/>
 <theory name="Modules_Nested_InnerFunc" proved="true">
  <goal name="inner_func&#39;vc" expl="VC for inner_func" proved="true">
- <proof prover="1"><result status="valid" time="0.004242" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.004242" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/lang/unary_op/why3session.xml b/creusot/tests/should_succeed/lang/unary_op/why3session.xml
index 996f05129..0c082c6da 100644
--- a/creusot/tests/should_succeed/lang/unary_op/why3session.xml
+++ b/creusot/tests/should_succeed/lang/unary_op/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="unary_op.mlcfg"/>
 <theory name="UnaryOp_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.004158" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.004158" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/lang/while_let/why3session.xml b/creusot/tests/should_succeed/lang/while_let/why3session.xml
index e3c1ac806..a13acc940 100644
--- a/creusot/tests/should_succeed/lang/while_let/why3session.xml
+++ b/creusot/tests/should_succeed/lang/while_let/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="while_let.mlcfg"/>
 <theory name="WhileLet_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.006241" steps="2"/></proof>
+ <proof prover="0"><result status="valid" time="0.006241" steps="2"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/list_index_mut/why3session.xml b/creusot/tests/should_succeed/list_index_mut/why3session.xml
index 255a3f908..86798025c 100644
--- a/creusot/tests/should_succeed/list_index_mut/why3session.xml
+++ b/creusot/tests/should_succeed/list_index_mut/why3session.xml
@@ -2,22 +2,22 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="list_index_mut.mlcfg"/>
 <theory name="ListIndexMut_IndexMut" proved="true">
  <goal name="index_mut&#39;vc" expl="VC for index_mut" proved="true">
- <proof prover="1"><result status="valid" time="0.098784" steps="2604"/></proof>
+ <proof prover="0"><result status="valid" time="0.098784" steps="2598"/></proof>
  </goal>
 </theory>
 <theory name="ListIndexMut_Write" proved="true">
  <goal name="write&#39;vc" expl="VC for write" proved="true">
- <proof prover="1"><result status="valid" time="0.009281" steps="88"/></proof>
+ <proof prover="0"><result status="valid" time="0.009281" steps="88"/></proof>
  </goal>
 </theory>
 <theory name="ListIndexMut_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.009247" steps="62"/></proof>
+ <proof prover="0"><result status="valid" time="0.009247" steps="62"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/list_reversal_lasso/why3session.xml b/creusot/tests/should_succeed/list_reversal_lasso/why3session.xml
index 5593d71e0..d67072bb8 100644
--- a/creusot/tests/should_succeed/list_reversal_lasso/why3session.xml
+++ b/creusot/tests/should_succeed/list_reversal_lasso/why3session.xml
@@ -3,62 +3,62 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="CVC4" version="1.8" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.11.2" timelimit="5" steplimit="0" memlimit="1000"/>
 <prover id="3" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="4" name="CVC5" version="1.0.5" timelimit="5" steplimit="0" memlimit="4000"/>
-<file format="mlcfg" proved="true">
+<prover id="5" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="6" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
+<file format="mlcfg">
 <path name=".."/><path name="list_reversal_lasso.mlcfg"/>
-<theory name="ListReversalLasso_Impl1_Index" proved="true">
- <goal name="index&#39;vc" expl="VC for index" proved="true">
- <proof prover="0"><result status="valid" time="0.100000" steps="14292"/></proof>
+<theory name="ListReversalLasso_Impl1_Index">
+ <goal name="index&#39;vc" expl="VC for index">
+ <proof prover="0" obsolete="true"><result status="valid" time="0.100000" steps="14292"/></proof>
  </goal>
 </theory>
-<theory name="ListReversalLasso_Impl2_IndexMut" proved="true">
- <goal name="index_mut&#39;vc" expl="VC for index_mut" proved="true">
- <proof prover="0"><result status="valid" time="0.130000" steps="21144"/></proof>
+<theory name="ListReversalLasso_Impl2_IndexMut">
+ <goal name="index_mut&#39;vc" expl="VC for index_mut">
+ <proof prover="0" obsolete="true"><result status="valid" time="0.130000" steps="21144"/></proof>
  </goal>
 </theory>
-<theory name="ListReversalLasso_Impl4_ListReversalSafe" proved="true">
- <goal name="list_reversal_safe&#39;vc" expl="VC for list_reversal_safe" proved="true">
- <proof prover="0" timelimit="5"><result status="valid" time="0.099612" steps="23586"/></proof>
+<theory name="ListReversalLasso_Impl4_ListReversalSafe">
+ <goal name="list_reversal_safe&#39;vc" expl="VC for list_reversal_safe">
+ <proof prover="0" timelimit="5" obsolete="true"><result status="valid" time="0.099612" steps="23586"/></proof>
  </goal>
 </theory>
-<theory name="ListReversalLasso_Impl4_ListReversalList" proved="true">
- <goal name="list_reversal_list&#39;vc" expl="VC for list_reversal_list" proved="true">
- <transf name="split_vc" proved="true" >
-  <goal name="list_reversal_list&#39;vc.0" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.090000" steps="15310"/></proof>
+<theory name="ListReversalLasso_Impl4_ListReversalList">
+ <goal name="list_reversal_list&#39;vc" expl="VC for list_reversal_list">
+ <transf name="split_vc" >
+  <goal name="list_reversal_list&#39;vc.0" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.090000" steps="15310"/></proof>
   </goal>
-  <goal name="list_reversal_list&#39;vc.1" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.100000" steps="14788"/></proof>
+  <goal name="list_reversal_list&#39;vc.1" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.100000" steps="14788"/></proof>
   </goal>
-  <goal name="list_reversal_list&#39;vc.2" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.080000" steps="16867"/></proof>
+  <goal name="list_reversal_list&#39;vc.2" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.080000" steps="16867"/></proof>
   </goal>
   <goal name="list_reversal_list&#39;vc.3" expl="postcondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.070000" steps="691"/></proof>
+  <proof prover="6"><result status="valid" time="0.070000" steps="691"/></proof>
   </goal>
-  <goal name="list_reversal_list&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.110000" steps="17723"/></proof>
+  <goal name="list_reversal_list&#39;vc.4" expl="precondition">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.110000" steps="17723"/></proof>
   </goal>
   <goal name="list_reversal_list&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.014740" steps="56"/></proof>
+  <proof prover="6"><result status="valid" time="0.014740" steps="55"/></proof>
   </goal>
   <goal name="list_reversal_list&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.019600" steps="58"/></proof>
+  <proof prover="6"><result status="valid" time="0.019600" steps="56"/></proof>
   </goal>
   <goal name="list_reversal_list&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.020939" steps="64"/></proof>
+  <proof prover="6"><result status="valid" time="0.020939" steps="62"/></proof>
   </goal>
   <goal name="list_reversal_list&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.016210" steps="56"/></proof>
+  <proof prover="6"><result status="valid" time="0.016210" steps="56"/></proof>
   </goal>
-  <goal name="list_reversal_list&#39;vc.9" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.110000" steps="17991"/></proof>
+  <goal name="list_reversal_list&#39;vc.9" expl="loop invariant preservation">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.110000" steps="17991"/></proof>
   </goal>
   <goal name="list_reversal_list&#39;vc.10" expl="loop invariant preservation" proved="true">
-  <proof prover="3" timelimit="5"><result status="valid" time="1.818433" steps="7726"/></proof>
+  <proof prover="6" timelimit="5"><result status="valid" time="0.510470" steps="7730"/></proof>
   </goal>
   <goal name="list_reversal_list&#39;vc.11" expl="loop invariant preservation" proved="true">
   <transf name="split_vc" proved="true" >
@@ -87,23 +87,23 @@
  </transf>
  </goal>
 </theory>
-<theory name="ListReversalLasso_Impl4_ListReversalLoop" proved="true">
- <goal name="list_reversal_loop&#39;vc" expl="VC for list_reversal_loop" proved="true">
- <transf name="split_vc" proved="true" >
-  <goal name="list_reversal_loop&#39;vc.0" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.080000" steps="14767"/></proof>
+<theory name="ListReversalLasso_Impl4_ListReversalLoop">
+ <goal name="list_reversal_loop&#39;vc" expl="VC for list_reversal_loop">
+ <transf name="split_vc" >
+  <goal name="list_reversal_loop&#39;vc.0" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.080000" steps="14767"/></proof>
   </goal>
-  <goal name="list_reversal_loop&#39;vc.1" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.140000" steps="15631"/></proof>
+  <goal name="list_reversal_loop&#39;vc.1" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.140000" steps="15631"/></proof>
   </goal>
-  <goal name="list_reversal_loop&#39;vc.2" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.080000" steps="15705"/></proof>
+  <goal name="list_reversal_loop&#39;vc.2" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.080000" steps="15705"/></proof>
   </goal>
-  <goal name="list_reversal_loop&#39;vc.3" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.110000" steps="17767"/></proof>
+  <goal name="list_reversal_loop&#39;vc.3" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.110000" steps="17767"/></proof>
   </goal>
   <goal name="list_reversal_loop&#39;vc.4" expl="assertion" proved="true">
-  <proof prover="3"><result status="valid" time="1.100014" steps="5417"/></proof>
+  <proof prover="6"><result status="valid" time="0.295628" steps="5318"/></proof>
   </goal>
   <goal name="list_reversal_loop&#39;vc.5" expl="postcondition" proved="true">
   <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
@@ -165,31 +165,31 @@
   </transf>
   </goal>
   <goal name="list_reversal_loop&#39;vc.6" expl="assertion" proved="true">
-  <proof prover="3"><result status="valid" time="0.020000" steps="235"/></proof>
+  <proof prover="6"><result status="valid" time="0.020000" steps="235"/></proof>
   </goal>
-  <goal name="list_reversal_loop&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.150000" steps="20765"/></proof>
+  <goal name="list_reversal_loop&#39;vc.7" expl="precondition">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.150000" steps="20765"/></proof>
   </goal>
   <goal name="list_reversal_loop&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.037369" steps="64"/></proof>
+  <proof prover="6"><result status="valid" time="0.037369" steps="63"/></proof>
   </goal>
   <goal name="list_reversal_loop&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.033165" steps="65"/></proof>
+  <proof prover="6"><result status="valid" time="0.033165" steps="64"/></proof>
   </goal>
   <goal name="list_reversal_loop&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.038181" steps="71"/></proof>
+  <proof prover="6"><result status="valid" time="0.038181" steps="70"/></proof>
   </goal>
   <goal name="list_reversal_loop&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.023187" steps="58"/></proof>
+  <proof prover="6"><result status="valid" time="0.023187" steps="57"/></proof>
   </goal>
-  <goal name="list_reversal_loop&#39;vc.12" expl="loop invariant preservation" proved="true">
-  <proof prover="0" timelimit="5"><result status="valid" time="0.080000" steps="18671"/></proof>
+  <goal name="list_reversal_loop&#39;vc.12" expl="loop invariant preservation">
+  <proof prover="0" timelimit="5" obsolete="true"><result status="valid" time="0.080000" steps="18671"/></proof>
   </goal>
   <goal name="list_reversal_loop&#39;vc.13" expl="loop invariant preservation" proved="true">
-  <proof prover="3" timelimit="5"><result status="valid" time="1.447366" steps="6982"/></proof>
+  <proof prover="6" timelimit="5"><result status="valid" time="0.383409" steps="6979"/></proof>
   </goal>
   <goal name="list_reversal_loop&#39;vc.14" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="1.147318" steps="5110"/></proof>
+  <proof prover="6"><result status="valid" time="0.302352" steps="5108"/></proof>
   </goal>
   <goal name="list_reversal_loop&#39;vc.15" expl="loop invariant preservation" proved="true">
   <transf name="split_vc" proved="true" >
@@ -218,38 +218,38 @@
  </transf>
  </goal>
 </theory>
-<theory name="ListReversalLasso_Impl4_ListReversalLasso" proved="true">
- <goal name="list_reversal_lasso&#39;vc" expl="VC for list_reversal_lasso" proved="true">
- <transf name="split_vc" proved="true" >
-  <goal name="list_reversal_lasso&#39;vc.0" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.144436" steps="15889"/></proof>
-  </goal>
-  <goal name="list_reversal_lasso&#39;vc.1" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.164080" steps="18106"/></proof>
-  </goal>
-  <goal name="list_reversal_lasso&#39;vc.2" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.168837" steps="18786"/></proof>
-  </goal>
-  <goal name="list_reversal_lasso&#39;vc.3" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.150000" steps="19736"/></proof>
-  </goal>
-  <goal name="list_reversal_lasso&#39;vc.4" expl="postcondition" proved="true">
-  <transf name="unfold" proved="true" arg1="lasso">
-   <goal name="list_reversal_lasso&#39;vc.4.0" expl="VC for list_reversal_lasso" proved="true">
-   <transf name="split_vc" proved="true" >
-    <goal name="list_reversal_lasso&#39;vc.4.0.0" expl="VC for list_reversal_lasso" proved="true">
-    <proof prover="0"><result status="valid" time="0.058838" steps="19884"/></proof>
+<theory name="ListReversalLasso_Impl4_ListReversalLasso">
+ <goal name="list_reversal_lasso&#39;vc" expl="VC for list_reversal_lasso">
+ <transf name="split_vc" >
+  <goal name="list_reversal_lasso&#39;vc.0" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.144436" steps="15889"/></proof>
+  </goal>
+  <goal name="list_reversal_lasso&#39;vc.1" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.164080" steps="18106"/></proof>
+  </goal>
+  <goal name="list_reversal_lasso&#39;vc.2" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.168837" steps="18786"/></proof>
+  </goal>
+  <goal name="list_reversal_lasso&#39;vc.3" expl="loop invariant init">
+  <proof prover="0" obsolete="true"><result status="valid" time="0.150000" steps="19736"/></proof>
+  </goal>
+  <goal name="list_reversal_lasso&#39;vc.4" expl="postcondition">
+  <transf name="unfold" arg1="lasso">
+   <goal name="list_reversal_lasso&#39;vc.4.0" expl="VC for list_reversal_lasso">
+   <transf name="split_vc" >
+    <goal name="list_reversal_lasso&#39;vc.4.0.0" expl="VC for list_reversal_lasso">
+    <proof prover="0" obsolete="true"><result status="valid" time="0.058838" steps="19884"/></proof>
     </goal>
     <goal name="list_reversal_lasso&#39;vc.4.0.1" expl="VC for list_reversal_lasso" proved="true">
-    <proof prover="3"><result status="valid" time="0.040000" steps="401"/></proof>
+    <proof prover="6"><result status="valid" time="0.040000" steps="400"/></proof>
     </goal>
-    <goal name="list_reversal_lasso&#39;vc.4.0.2" expl="VC for list_reversal_lasso" proved="true">
-    <transf name="replace" proved="true" arg1="mid" arg2="mid1">
-     <goal name="list_reversal_lasso&#39;vc.4.0.2.0" expl="VC for list_reversal_lasso" proved="true">
-     <proof prover="0"><result status="valid" time="0.422594" steps="42969"/></proof>
+    <goal name="list_reversal_lasso&#39;vc.4.0.2" expl="VC for list_reversal_lasso">
+    <transf name="replace" arg1="mid" arg2="mid1">
+     <goal name="list_reversal_lasso&#39;vc.4.0.2.0" expl="VC for list_reversal_lasso">
+     <proof prover="0" obsolete="true"><result status="valid" time="0.422594" steps="42969"/></proof>
      </goal>
      <goal name="list_reversal_lasso&#39;vc.4.0.2.1" expl="equality hypothesis" proved="true">
-     <proof prover="3"><result status="valid" time="0.151570" steps="459"/></proof>
+     <proof prover="6"><result status="valid" time="0.031036" steps="458"/></proof>
      </goal>
     </transf>
     </goal>
@@ -284,7 +284,7 @@
      </transf>
      </goal>
      <goal name="list_reversal_lasso&#39;vc.4.0.3.1" expl="equality hypothesis" proved="true">
-     <proof prover="3"><result status="valid" time="0.040000" steps="459"/></proof>
+     <proof prover="6"><result status="valid" time="0.040000" steps="458"/></proof>
      </goal>
     </transf>
     </goal>
@@ -293,25 +293,25 @@
   </transf>
   </goal>
   <goal name="list_reversal_lasso&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="3" timelimit="5"><result status="valid" time="0.217285" steps="1073"/></proof>
+  <proof prover="6" timelimit="5"><result status="valid" time="0.068267" steps="1073"/></proof>
   </goal>
   <goal name="list_reversal_lasso&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.036739" steps="70"/></proof>
+  <proof prover="6"><result status="valid" time="0.036739" steps="70"/></proof>
   </goal>
   <goal name="list_reversal_lasso&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.038848" steps="71"/></proof>
+  <proof prover="6"><result status="valid" time="0.038848" steps="70"/></proof>
   </goal>
   <goal name="list_reversal_lasso&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.038466" steps="77"/></proof>
+  <proof prover="6"><result status="valid" time="0.038466" steps="77"/></proof>
   </goal>
   <goal name="list_reversal_lasso&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.028086" steps="57"/></proof>
+  <proof prover="6"><result status="valid" time="0.028086" steps="57"/></proof>
   </goal>
-  <goal name="list_reversal_lasso&#39;vc.10" expl="loop invariant preservation" proved="true">
-  <proof prover="0" timelimit="5"><result status="valid" time="0.069828" steps="20720"/></proof>
+  <goal name="list_reversal_lasso&#39;vc.10" expl="loop invariant preservation">
+  <proof prover="0" timelimit="5" obsolete="true"><result status="valid" time="0.069828" steps="20720"/></proof>
   </goal>
-  <goal name="list_reversal_lasso&#39;vc.11" expl="loop invariant preservation" proved="true">
-  <transf name="split_vc" proved="true" >
+  <goal name="list_reversal_lasso&#39;vc.11" expl="loop invariant preservation">
+  <transf name="split_vc" >
    <goal name="list_reversal_lasso&#39;vc.11.0" expl="loop invariant preservation" proved="true">
    <transf name="inline_goal" proved="true" >
     <goal name="list_reversal_lasso&#39;vc.11.0.0" expl="loop invariant preservation" proved="true">
@@ -340,8 +340,8 @@
     </goal>
    </transf>
    </goal>
-   <goal name="list_reversal_lasso&#39;vc.11.1" expl="loop invariant preservation" proved="true">
-   <proof prover="0"><result status="valid" time="0.516542" steps="66144"/></proof>
+   <goal name="list_reversal_lasso&#39;vc.11.1" expl="loop invariant preservation">
+   <proof prover="0" obsolete="true"><result status="valid" time="0.516542" steps="66144"/></proof>
    </goal>
    <goal name="list_reversal_lasso&#39;vc.11.2" expl="loop invariant preservation" proved="true">
    <transf name="inline_goal" proved="true" >
@@ -533,42 +533,42 @@
  </transf>
  </goal>
 </theory>
-<theory name="ListReversalLasso_Impl4_FindPtrInSeq_Impl" proved="true">
- <goal name="find_ptr_in_seq&#39;vc" expl="VC for find_ptr_in_seq" proved="true">
- <proof prover="0" timelimit="5"><result status="valid" time="0.070000" steps="15617"/></proof>
+<theory name="ListReversalLasso_Impl4_FindPtrInSeq_Impl">
+ <goal name="find_ptr_in_seq&#39;vc" expl="VC for find_ptr_in_seq">
+ <proof prover="0" timelimit="5" obsolete="true"><result status="valid" time="0.070000" steps="15617"/></proof>
  </goal>
 </theory>
 <theory name="ListReversalLasso_Impl4_Pigeon_Impl" proved="true">
  <goal name="pigeon&#39;vc" expl="VC for pigeon" proved="true">
- <proof prover="2"><result status="valid" time="0.173548" steps="689086"/></proof>
+ <proof prover="5" timelimit="5"><result status="valid" time="0.110611" steps="603162"/></proof>
  </goal>
 </theory>
 <theory name="ListReversalLasso_Impl4_FindLassoAux_Impl" proved="true">
  <goal name="find_lasso_aux&#39;vc" expl="VC for find_lasso_aux" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="find_lasso_aux&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.010000" steps="17"/></proof>
+  <proof prover="6"><result status="valid" time="0.010000" steps="16"/></proof>
   </goal>
   <goal name="find_lasso_aux&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.029977" steps="26"/></proof>
+  <proof prover="6"><result status="valid" time="0.029977" steps="26"/></proof>
   </goal>
   <goal name="find_lasso_aux&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.010000" steps="31"/></proof>
+  <proof prover="6"><result status="valid" time="0.010000" steps="30"/></proof>
   </goal>
   <goal name="find_lasso_aux&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.062282" steps="76104"/></proof>
+  <proof prover="5"><result status="valid" time="0.062282" steps="78450"/></proof>
   </goal>
   <goal name="find_lasso_aux&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.010000" steps="122"/></proof>
+  <proof prover="6"><result status="valid" time="0.010000" steps="121"/></proof>
   </goal>
   <goal name="find_lasso_aux&#39;vc.5" expl="variant decrease" proved="true">
-  <proof prover="3"><result status="valid" time="0.000000" steps="30"/></proof>
+  <proof prover="6"><result status="valid" time="0.000000" steps="30"/></proof>
   </goal>
   <goal name="find_lasso_aux&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.000000" steps="30"/></proof>
+  <proof prover="6"><result status="valid" time="0.000000" steps="30"/></proof>
   </goal>
   <goal name="find_lasso_aux&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.010000" steps="132"/></proof>
+  <proof prover="6"><result status="valid" time="0.010000" steps="131"/></proof>
   </goal>
   <goal name="find_lasso_aux&#39;vc.8" expl="precondition" proved="true">
   <transf name="split_vc" proved="true" >
@@ -595,14 +595,14 @@
   </transf>
   </goal>
   <goal name="find_lasso_aux&#39;vc.9" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.353837" steps="363157"/></proof>
+  <proof prover="5"><result status="valid" time="0.086524" steps="367999"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="ListReversalLasso_Impl4_FindLasso_Impl" proved="true">
  <goal name="find_lasso&#39;vc" expl="VC for find_lasso" proved="true">
- <proof prover="4" memlimit="1000"><result status="valid" time="0.200725" steps="13245"/></proof>
+ <proof prover="4" memlimit="1000"><result status="valid" time="0.037699" steps="12647"/></proof>
  </goal>
 </theory>
 <theory name="ListReversalLasso_Impl1" proved="true">
diff --git a/creusot/tests/should_succeed/list_reversal_lasso/why3shapes.gz b/creusot/tests/should_succeed/list_reversal_lasso/why3shapes.gz
index d00043363..f86ee3d4c 100644
Binary files a/creusot/tests/should_succeed/list_reversal_lasso/why3shapes.gz and b/creusot/tests/should_succeed/list_reversal_lasso/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/mapping_test/why3session.xml b/creusot/tests/should_succeed/mapping_test/why3session.xml
index c11e6a928..5b6168876 100644
--- a/creusot/tests/should_succeed/mapping_test/why3session.xml
+++ b/creusot/tests/should_succeed/mapping_test/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="mapping_test.mlcfg"/>
 <theory name="MappingTest_Incr" proved="true">
  <goal name="incr&#39;vc" expl="VC for incr" proved="true">
- <proof prover="1"><result status="valid" time="0.029426" steps="799"/></proof>
+ <proof prover="0"><result status="valid" time="0.029426" steps="796"/></proof>
  </goal>
 </theory>
 <theory name="MappingTest_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.009789" steps="148"/></proof>
+ <proof prover="0"><result status="valid" time="0.009789" steps="148"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/match_int/why3session.xml b/creusot/tests/should_succeed/match_int/why3session.xml
index 400838f97..87c3b9806 100644
--- a/creusot/tests/should_succeed/match_int/why3session.xml
+++ b/creusot/tests/should_succeed/match_int/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="match_int.mlcfg"/>
 <theory name="MatchInt_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.005815" steps="9"/></proof>
+ <proof prover="0"><result status="valid" time="0.005815" steps="9"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/mc91/why3session.xml b/creusot/tests/should_succeed/mc91/why3session.xml
index 733e63d20..a1957f31e 100644
--- a/creusot/tests/should_succeed/mc91/why3session.xml
+++ b/creusot/tests/should_succeed/mc91/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="mc91.mlcfg"/>
 <theory name="Mc91_Mc91" proved="true">
  <goal name="mc91&#39;vc" expl="VC for mc91" proved="true">
- <proof prover="1"><result status="valid" time="0.007568" steps="85"/></proof>
+ <proof prover="0"><result status="valid" time="0.007568" steps="87"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/mutex/why3session.xml b/creusot/tests/should_succeed/mutex/why3session.xml
index 243ab338b..6dac3181c 100644
--- a/creusot/tests/should_succeed/mutex/why3session.xml
+++ b/creusot/tests/should_succeed/mutex/why3session.xml
@@ -4,12 +4,12 @@
 <why3session shape_version="6">
 <prover id="0" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="3" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="mutex.mlcfg"/>
 <theory name="Mutex_Impl3_Call" proved="true">
  <goal name="call&#39;vc" expl="VC for call" proved="true">
- <proof prover="3"><result status="valid" time="0.040000" steps="32728"/></proof>
+ <proof prover="2"><result status="valid" time="0.017331" steps="29961"/></proof>
  </goal>
 </theory>
 <theory name="Mutex_Concurrent" proved="true">
diff --git a/creusot/tests/should_succeed/option/why3session.xml b/creusot/tests/should_succeed/option/why3session.xml
index 51bab34c4..0e34268e6 100644
--- a/creusot/tests/should_succeed/option/why3session.xml
+++ b/creusot/tests/should_succeed/option/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="option.mlcfg"/>
 <theory name="Option_TestOption" proved="true">
  <goal name="test_option&#39;vc" expl="VC for test_option" proved="true">
- <proof prover="1"><result status="valid" time="0.057603" steps="139867"/></proof>
+ <proof prover="0"><result status="valid" time="0.111139" steps="322310"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/ord_trait/why3session.xml b/creusot/tests/should_succeed/ord_trait/why3session.xml
index 963905d91..2b9e14eeb 100644
--- a/creusot/tests/should_succeed/ord_trait/why3session.xml
+++ b/creusot/tests/should_succeed/ord_trait/why3session.xml
@@ -2,13 +2,13 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="ord_trait.mlcfg"/>
 <theory name="OrdTrait_X" proved="true">
  <goal name="x&#39;vc" expl="VC for x" proved="true">
- <proof prover="0"><result status="valid" time="0.008207" steps="6274"/></proof>
+ <proof prover="2"><result status="valid" time="0.013239" steps="5565"/></proof>
  </goal>
 </theory>
 <theory name="OrdTrait_GtOrLe" proved="true">
diff --git a/creusot/tests/should_succeed/projection_toggle/why3session.xml b/creusot/tests/should_succeed/projection_toggle/why3session.xml
index df1fbf31a..2504fe914 100644
--- a/creusot/tests/should_succeed/projection_toggle/why3session.xml
+++ b/creusot/tests/should_succeed/projection_toggle/why3session.xml
@@ -3,7 +3,7 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="projection_toggle.mlcfg"/>
 <theory name="ProjectionToggle_ProjToggle" proved="true">
@@ -13,7 +13,7 @@
 </theory>
 <theory name="ProjectionToggle_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.016003" steps="151"/></proof>
+ <proof prover="2"><result status="valid" time="0.016003" steps="151"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/resolve_uninit/why3session.xml b/creusot/tests/should_succeed/resolve_uninit/why3session.xml
index 3a292395a..80d3400f8 100644
--- a/creusot/tests/should_succeed/resolve_uninit/why3session.xml
+++ b/creusot/tests/should_succeed/resolve_uninit/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="resolve_uninit.mlcfg"/>
 <theory name="ResolveUninit_MaybeUninit" proved="true">
  <goal name="maybe_uninit&#39;vc" expl="VC for maybe_uninit" proved="true">
- <proof prover="0"><result status="valid" time="0.005354" steps="9"/></proof>
+ <proof prover="1"><result status="valid" time="0.005354" steps="9"/></proof>
  </goal>
 </theory>
 <theory name="ResolveUninit_InitJoin" proved="true">
  <goal name="init_join&#39;vc" expl="VC for init_join" proved="true">
- <proof prover="0"><result status="valid" time="0.009232" steps="78"/></proof>
+ <proof prover="1"><result status="valid" time="0.009232" steps="78"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/rusthorn/inc_max/why3session.xml b/creusot/tests/should_succeed/rusthorn/inc_max/why3session.xml
index bb35d3531..c441b1b2b 100644
--- a/creusot/tests/should_succeed/rusthorn/inc_max/why3session.xml
+++ b/creusot/tests/should_succeed/rusthorn/inc_max/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="inc_max.mlcfg"/>
 <theory name="IncMax_TakeMax" proved="true">
  <goal name="take_max&#39;vc" expl="VC for take_max" proved="true">
- <proof prover="1"><result status="valid" time="0.011178" steps="134"/></proof>
+ <proof prover="0"><result status="valid" time="0.011178" steps="134"/></proof>
  </goal>
 </theory>
 <theory name="IncMax_IncMax" proved="true">
  <goal name="inc_max&#39;vc" expl="VC for inc_max" proved="true">
- <proof prover="1"><result status="valid" time="0.024030" steps="509"/></proof>
+ <proof prover="0"><result status="valid" time="0.024030" steps="516"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/rusthorn/inc_max_3/why3session.xml b/creusot/tests/should_succeed/rusthorn/inc_max_3/why3session.xml
index bbf5feac9..7fd8fe4c4 100644
--- a/creusot/tests/should_succeed/rusthorn/inc_max_3/why3session.xml
+++ b/creusot/tests/should_succeed/rusthorn/inc_max_3/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="inc_max_3.mlcfg"/>
 <theory name="IncMax3_IncMax3" proved="true">
  <goal name="inc_max_3&#39;vc" expl="VC for inc_max_3" proved="true">
- <proof prover="0"><result status="valid" time="0.013956" steps="52057"/></proof>
+ <proof prover="1"><result status="valid" time="0.017213" steps="47920"/></proof>
  </goal>
 </theory>
 <theory name="IncMax3_TestIncMax3" proved="true">
  <goal name="test_inc_max_3&#39;vc" expl="VC for test_inc_max_3" proved="true">
- <proof prover="0"><result status="valid" time="0.012366" steps="21743"/></proof>
+ <proof prover="1"><result status="valid" time="0.016236" steps="14916"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/rusthorn/inc_max_many/why3session.xml b/creusot/tests/should_succeed/rusthorn/inc_max_many/why3session.xml
index 398e74165..aca5fccba 100644
--- a/creusot/tests/should_succeed/rusthorn/inc_max_many/why3session.xml
+++ b/creusot/tests/should_succeed/rusthorn/inc_max_many/why3session.xml
@@ -2,7 +2,7 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="inc_max_many.mlcfg"/>
@@ -13,7 +13,7 @@
 </theory>
 <theory name="IncMaxMany_IncMaxMany" proved="true">
  <goal name="inc_max_many&#39;vc" expl="VC for inc_max_many" proved="true">
- <proof prover="1"><result status="valid" time="0.016910" steps="94528"/></proof>
+ <proof prover="0"><result status="valid" time="0.020667" steps="45829"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/rusthorn/inc_max_repeat/why3session.xml b/creusot/tests/should_succeed/rusthorn/inc_max_repeat/why3session.xml
index 4f024b61d..a4ec1bf37 100644
--- a/creusot/tests/should_succeed/rusthorn/inc_max_repeat/why3session.xml
+++ b/creusot/tests/should_succeed/rusthorn/inc_max_repeat/why3session.xml
@@ -2,18 +2,18 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="3" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="inc_max_repeat.mlcfg"/>
 <theory name="IncMaxRepeat_TakeMax" proved="true">
  <goal name="take_max&#39;vc" expl="VC for take_max" proved="true">
- <proof prover="3"><result status="valid" time="0.010682" steps="134"/></proof>
+ <proof prover="2"><result status="valid" time="0.010682" steps="134"/></proof>
  </goal>
 </theory>
 <theory name="IncMaxRepeat_IncMaxRepeat" proved="true">
  <goal name="inc_max_repeat&#39;vc" expl="VC for inc_max_repeat" proved="true">
- <proof prover="0"><result status="valid" time="0.829879" steps="1639833"/></proof>
+ <proof prover="1"><result status="valid" time="0.172157" steps="951036"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/rusthorn/inc_max_repeat/why3shapes.gz b/creusot/tests/should_succeed/rusthorn/inc_max_repeat/why3shapes.gz
index 56bbacf6c..d8ac22421 100644
Binary files a/creusot/tests/should_succeed/rusthorn/inc_max_repeat/why3shapes.gz and b/creusot/tests/should_succeed/rusthorn/inc_max_repeat/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/rusthorn/inc_some_2_list/why3session.xml b/creusot/tests/should_succeed/rusthorn/inc_some_2_list/why3session.xml
index c8bb688dc..3735010cb 100644
--- a/creusot/tests/should_succeed/rusthorn/inc_some_2_list/why3session.xml
+++ b/creusot/tests/should_succeed/rusthorn/inc_some_2_list/why3session.xml
@@ -2,8 +2,8 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="inc_some_2_list.mlcfg"/>
 <theory name="IncSome2List_Impl0_LemmaSumNonneg_Impl" proved="true">
@@ -13,7 +13,7 @@
 </theory>
 <theory name="IncSome2List_Impl0_SumX" proved="true">
  <goal name="sum_x&#39;vc" expl="VC for sum_x" proved="true">
- <proof prover="2"><result status="valid" time="0.011254" steps="8145"/></proof>
+ <proof prover="0"><result status="valid" time="0.012260" steps="6720"/></proof>
  </goal>
 </theory>
 <theory name="IncSome2List_Impl0_TakeSomeRest" proved="true">
@@ -23,7 +23,7 @@
 </theory>
 <theory name="IncSome2List_IncSome2List" proved="true">
  <goal name="inc_some_2_list&#39;vc" expl="VC for inc_some_2_list" proved="true">
- <proof prover="2"><result status="valid" time="0.014432" steps="35591"/></proof>
+ <proof prover="0"><result status="valid" time="0.019182" steps="33723"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/rusthorn/inc_some_2_tree/why3session.xml b/creusot/tests/should_succeed/rusthorn/inc_some_2_tree/why3session.xml
index 2ac088923..cfe68cf19 100644
--- a/creusot/tests/should_succeed/rusthorn/inc_some_2_tree/why3session.xml
+++ b/creusot/tests/should_succeed/rusthorn/inc_some_2_tree/why3session.xml
@@ -2,7 +2,7 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="inc_some_2_tree.mlcfg"/>
@@ -13,17 +13,17 @@
 </theory>
 <theory name="IncSome2Tree_Impl0_SumX" proved="true">
  <goal name="sum_x&#39;vc" expl="VC for sum_x" proved="true">
- <proof prover="1"><result status="valid" time="0.013016" steps="13052"/></proof>
+ <proof prover="0"><result status="valid" time="0.013090" steps="12932"/></proof>
  </goal>
 </theory>
 <theory name="IncSome2Tree_Impl0_TakeSomeRest" proved="true">
  <goal name="take_some_rest&#39;vc" expl="VC for take_some_rest" proved="true">
- <proof prover="1"><result status="valid" time="0.021331" steps="81443"/></proof>
+ <proof prover="0"><result status="valid" time="0.021724" steps="212881"/></proof>
  </goal>
 </theory>
 <theory name="IncSome2Tree_IncSome2Tree" proved="true">
  <goal name="inc_some_2_tree&#39;vc" expl="VC for inc_some_2_tree" proved="true">
- <proof prover="1"><result status="valid" time="0.013779" steps="36099"/></proof>
+ <proof prover="0"><result status="valid" time="0.019419" steps="33696"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/rusthorn/inc_some_list/why3session.xml b/creusot/tests/should_succeed/rusthorn/inc_some_list/why3session.xml
index 57dd42f5d..96dfd3274 100644
--- a/creusot/tests/should_succeed/rusthorn/inc_some_list/why3session.xml
+++ b/creusot/tests/should_succeed/rusthorn/inc_some_list/why3session.xml
@@ -2,8 +2,8 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="inc_some_list.mlcfg"/>
 <theory name="IncSomeList_Impl0_LemmaSumNonneg_Impl" proved="true">
@@ -13,7 +13,7 @@
 </theory>
 <theory name="IncSomeList_Impl0_SumX" proved="true">
  <goal name="sum_x&#39;vc" expl="VC for sum_x" proved="true">
- <proof prover="0"><result status="valid" time="0.010016" steps="8145"/></proof>
+ <proof prover="2"><result status="valid" time="0.013484" steps="6720"/></proof>
  </goal>
 </theory>
 <theory name="IncSomeList_Impl0_TakeSome" proved="true">
diff --git a/creusot/tests/should_succeed/rusthorn/inc_some_tree/why3session.xml b/creusot/tests/should_succeed/rusthorn/inc_some_tree/why3session.xml
index cd17b7232..acd099faa 100644
--- a/creusot/tests/should_succeed/rusthorn/inc_some_tree/why3session.xml
+++ b/creusot/tests/should_succeed/rusthorn/inc_some_tree/why3session.xml
@@ -3,7 +3,7 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="inc_some_tree.mlcfg"/>
 <theory name="IncSomeTree_Impl0_LemmaSumNonneg_Impl" proved="true">
@@ -13,12 +13,12 @@
 </theory>
 <theory name="IncSomeTree_Impl0_SumX" proved="true">
  <goal name="sum_x&#39;vc" expl="VC for sum_x" proved="true">
- <proof prover="1"><result status="valid" time="0.013856" steps="13052"/></proof>
+ <proof prover="2"><result status="valid" time="0.013884" steps="12932"/></proof>
  </goal>
 </theory>
 <theory name="IncSomeTree_Impl0_TakeSome" proved="true">
  <goal name="take_some&#39;vc" expl="VC for take_some" proved="true">
- <proof prover="1"><result status="valid" time="0.015652" steps="70654"/></proof>
+ <proof prover="2"><result status="valid" time="0.023870" steps="88154"/></proof>
  </goal>
 </theory>
 <theory name="IncSomeTree_IncSomeTree" proved="true">
diff --git a/creusot/tests/should_succeed/selection_sort_generic/why3session.xml b/creusot/tests/should_succeed/selection_sort_generic/why3session.xml
index 3c4f0f778..d4d47b5b2 100644
--- a/creusot/tests/should_succeed/selection_sort_generic/why3session.xml
+++ b/creusot/tests/should_succeed/selection_sort_generic/why3session.xml
@@ -2,107 +2,106 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="CVC4" version="1.8" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="2" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="5" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="4" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="selection_sort_generic.mlcfg"/>
 <theory name="SelectionSortGeneric_SelectionSort" proved="true">
  <goal name="selection_sort&#39;vc" expl="VC for selection_sort" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="selection_sort&#39;vc.0" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.044225" steps="8"/></proof>
+  <proof prover="4"><result status="valid" time="0.044225" steps="8"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.036574" steps="12"/></proof>
+  <proof prover="4"><result status="valid" time="0.036574" steps="12"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="12"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="12"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.030580" steps="22"/></proof>
+  <proof prover="4"><result status="valid" time="0.030580" steps="22"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="22"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="22"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.5" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="32"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="32"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.6" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="91"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="90"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.7" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="80"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="80"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.8" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="84"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="84"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.016432" steps="47"/></proof>
+  <proof prover="4"><result status="valid" time="0.016432" steps="46"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.10" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.026885" steps="52"/></proof>
+  <proof prover="4"><result status="valid" time="0.026885" steps="52"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.11" expl="postcondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.020000" steps="279"/></proof>
+  <proof prover="4"><result status="valid" time="0.020000" steps="278"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.12" expl="postcondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="61"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="59"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.13" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.043977" steps="66"/></proof>
+  <proof prover="4"><result status="valid" time="0.043977" steps="65"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.14" expl="integer overflow" proved="true">
-  <proof prover="5"><result status="valid" time="0.030000" steps="583"/></proof>
+  <proof prover="4"><result status="valid" time="0.030000" steps="583"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="66"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="66"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.047018" steps="87"/></proof>
+  <proof prover="4"><result status="valid" time="0.047018" steps="86"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.17" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="74"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="74"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.18" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="99"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="99"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.19" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.020000" steps="509"/></proof>
+  <proof prover="4"><result status="valid" time="0.020000" steps="508"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.20" expl="loop invariant init" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="107"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="105"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.21" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.033361" steps="111"/></proof>
+  <proof prover="4"><result status="valid" time="0.033361" steps="109"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.22" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.010000" steps="123"/></proof>
+  <proof prover="4"><result status="valid" time="0.010000" steps="122"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.23" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.177677" steps="1145"/></proof>
+  <proof prover="4"><result status="valid" time="0.177677" steps="1145"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.24" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.101040" steps="686"/></proof>
+  <proof prover="4"><result status="valid" time="0.101040" steps="685"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.25" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.019355" steps="139"/></proof>
+  <proof prover="4"><result status="valid" time="0.019355" steps="138"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.26" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.033242" steps="140"/></proof>
+  <proof prover="4"><result status="valid" time="0.033242" steps="139"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.27" expl="assertion" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="selection_sort&#39;vc.27.0" expl="assertion" proved="true">
    <transf name="assert" proved="true" arg1="(length (inner produced) = length (inner produced2) + 1)">
     <goal name="selection_sort&#39;vc.27.0.0" expl="asserted formula" proved="true">
-    <proof prover="5"><result status="valid" time="0.052939" steps="158"/></proof>
+    <proof prover="4"><result status="valid" time="0.052939" steps="157"/></proof>
     </goal>
     <goal name="selection_sort&#39;vc.27.0.1" expl="assertion" proved="true">
     <transf name="remove" proved="true" arg1="one,(-),(&gt;),(&gt;=),uint64&#39;maxInt,uint64&#39;minInt,max_uint64,length1,singleton,cons,snoc,(++),mem,iseq,occ,occ_all,permut,mAX&#39;,is_inhabited,sorted_range,sorted,permutation_of,shallow_model,Mul_distr_r,Comm,Unitary,NonTrivialRing,Total,CompatOrderAdd,CompatOrderMult,Mod_inf,Div_mult,Mod_mult,Numof_append,Numof_left_no_add,Numof_left_add,Empty,Full,numof_increasing,numof_strictly_increasing,numof_change_any,numof_change_some,numof_change_equiv,length_nonnegative,([&lt;-])&#39;def,singleton&#39;spec,cons&#39;spec,snoc&#39;spec,mem_append,occ_cons,occ_tail,append_num_occ,exchange_set,permut_sym,permut_trans,permut_exists,new&#39;spec,produces_trans_spec,produces_refl_spec,is_inhabited_spec">
      <goal name="selection_sort&#39;vc.27.0.1.0" expl="assertion" proved="true">
-     <proof prover="1"><result status="valid" time="0.225401" steps="508596"/></proof>
+     <proof prover="3"><result status="valid" time="0.061385" steps="349439"/></proof>
      </goal>
     </transf>
     </goal>
@@ -111,27 +110,27 @@
   </transf>
   </goal>
   <goal name="selection_sort&#39;vc.28" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.020000" steps="241726"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="245051"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.29" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.498968" steps="3413"/></proof>
+  <proof prover="4"><result status="valid" time="0.188252" steps="3395"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.30" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.040000" steps="619"/></proof>
+  <proof prover="4"><result status="valid" time="0.040000" steps="618"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.31" expl="loop invariant preservation" proved="true">
   <transf name="instantiate" proved="true" arg1="deep_model_spec" arg2="( * v)">
    <goal name="selection_sort&#39;vc.31.0" expl="loop invariant preservation" proved="true">
    <transf name="assert" proved="true" arg1="(forall x:deepModelTy, y:deepModelTy. le_log x y = True &lt;-&gt; not cmp_log x y = C_Greater)">
     <goal name="selection_sort&#39;vc.31.0.0" expl="asserted formula" proved="true">
-    <proof prover="5"><result status="valid" time="0.156159" steps="1341"/></proof>
+    <proof prover="4"><result status="valid" time="0.156159" steps="1340"/></proof>
     </goal>
     <goal name="selection_sort&#39;vc.31.0.1" expl="loop invariant preservation" proved="true">
     <transf name="inline_goal" proved="true" >
      <goal name="selection_sort&#39;vc.31.0.1.0" expl="loop invariant preservation" proved="true">
      <transf name="split_vc" proved="true" >
       <goal name="selection_sort&#39;vc.31.0.1.0.0" expl="loop invariant preservation" proved="true">
-      <proof prover="0"><result status="valid" time="0.852257" steps="136631"/></proof>
+      <proof prover="2"><result status="valid" time="0.978389" steps="238341"/></proof>
       </goal>
      </transf>
      </goal>
@@ -142,49 +141,49 @@
   </transf>
   </goal>
   <goal name="selection_sort&#39;vc.32" expl="loop invariant preservation" proved="true">
-  <proof prover="5"><result status="valid" time="0.199512" steps="981"/></proof>
+  <proof prover="4"><result status="valid" time="0.064462" steps="979"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.33" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.200759" steps="1218"/></proof>
+  <proof prover="4"><result status="valid" time="0.077391" steps="1217"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.34" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.031688" steps="137"/></proof>
+  <proof prover="4"><result status="valid" time="0.031688" steps="135"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.35" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.036204" steps="137"/></proof>
+  <proof prover="4"><result status="valid" time="0.036204" steps="137"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.36" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.028065" steps="112"/></proof>
+  <proof prover="4"><result status="valid" time="0.028065" steps="112"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.37" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.035101" steps="549"/></proof>
+  <proof prover="4"><result status="valid" time="0.035101" steps="549"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.38" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.118334" steps="139"/></proof>
+  <proof prover="4"><result status="valid" time="0.118334" steps="138"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.39" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.017093" steps="141"/></proof>
+  <proof prover="4"><result status="valid" time="0.017093" steps="139"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.40" expl="type invariant" proved="true">
-  <proof prover="5"><result status="valid" time="0.029730" steps="118"/></proof>
+  <proof prover="4"><result status="valid" time="0.029730" steps="118"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.41" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.032602" steps="120"/></proof>
+  <proof prover="4"><result status="valid" time="0.032602" steps="120"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.42" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.031963" steps="120"/></proof>
+  <proof prover="4"><result status="valid" time="0.031963" steps="120"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.43" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.119854" steps="232035"/></proof>
+  <proof prover="3"><result status="valid" time="0.119854" steps="233584"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.44" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.220000" steps="38323"/></proof>
+  <proof prover="2"><result status="valid" time="0.220000" steps="37192"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.45" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.506144" steps="77481"/></proof>
+  <proof prover="2"><result status="valid" time="0.305224" steps="75347"/></proof>
   </goal>
   <goal name="selection_sort&#39;vc.46" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.255950" steps="44362"/></proof>
+  <proof prover="2"><result status="valid" time="0.255950" steps="43188"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/selection_sort_generic/why3shapes.gz b/creusot/tests/should_succeed/selection_sort_generic/why3shapes.gz
index bc9853f37..98e3e8a1b 100644
Binary files a/creusot/tests/should_succeed/selection_sort_generic/why3shapes.gz and b/creusot/tests/should_succeed/selection_sort_generic/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/slices/01/why3session.xml b/creusot/tests/should_succeed/slices/01/why3session.xml
index f92d50c77..70ba52aa1 100644
--- a/creusot/tests/should_succeed/slices/01/why3session.xml
+++ b/creusot/tests/should_succeed/slices/01/why3session.xml
@@ -2,23 +2,23 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="01.mlcfg"/>
 <theory name="C01_IndexSlice" proved="true">
  <goal name="index_slice&#39;vc" expl="VC for index_slice" proved="true">
- <proof prover="2"><result status="valid" time="0.014857" steps="51730"/></proof>
+ <proof prover="0"><result status="valid" time="0.014857" steps="51439"/></proof>
  </goal>
 </theory>
 <theory name="C01_IndexMutSlice" proved="true">
  <goal name="index_mut_slice&#39;vc" expl="VC for index_mut_slice" proved="true">
- <proof prover="1"><result status="valid" time="0.017381" steps="195"/></proof>
+ <proof prover="3"><result status="valid" time="0.017381" steps="195"/></proof>
  </goal>
 </theory>
 <theory name="C01_SliceFirst" proved="true">
  <goal name="slice_first&#39;vc" expl="VC for slice_first" proved="true">
- <proof prover="1"><result status="valid" time="0.014152" steps="125"/></proof>
+ <proof prover="3"><result status="valid" time="0.014152" steps="124"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/slices/01/why3shapes.gz b/creusot/tests/should_succeed/slices/01/why3shapes.gz
index 6e4381aa0..3d7ed1a93 100644
Binary files a/creusot/tests/should_succeed/slices/01/why3shapes.gz and b/creusot/tests/should_succeed/slices/01/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/slices/02_std/why3session.xml b/creusot/tests/should_succeed/slices/02_std/why3session.xml
index e597d67f8..93d83d0dc 100644
--- a/creusot/tests/should_succeed/slices/02_std/why3session.xml
+++ b/creusot/tests/should_succeed/slices/02_std/why3session.xml
@@ -2,36 +2,36 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="02_std.mlcfg"/>
 <theory name="C02Std_BinarySearch" proved="true">
  <goal name="binary_search&#39;vc" expl="VC for binary_search" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="binary_search&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.010000" steps="79"/></proof>
+  <proof prover="1"><result status="valid" time="0.010000" steps="82"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.017370" steps="19"/></proof>
+  <proof prover="1"><result status="valid" time="0.017370" steps="19"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.013155" steps="20"/></proof>
+  <proof prover="1"><result status="valid" time="0.013155" steps="20"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.3" expl="precondition" proved="true">
   <transf name="destruct_term" proved="true" arg1="_5">
    <goal name="binary_search&#39;vc.3.0" expl="precondition" proved="true">
-   <proof prover="0"><result status="valid" time="0.126562" steps="982"/></proof>
+   <proof prover="1"><result status="valid" time="0.126562" steps="984"/></proof>
    </goal>
    <goal name="binary_search&#39;vc.3.1" expl="precondition" proved="true">
-   <proof prover="0"><result status="valid" time="0.020800" steps="44"/></proof>
+   <proof prover="1"><result status="valid" time="0.020800" steps="44"/></proof>
    </goal>
   </transf>
   </goal>
   <goal name="binary_search&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.022953" steps="25"/></proof>
+  <proof prover="1"><result status="valid" time="0.022953" steps="25"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.5" expl="assertion" proved="true">
-  <proof prover="0"><result status="valid" time="0.010000" steps="26"/></proof>
+  <proof prover="1"><result status="valid" time="0.010000" steps="26"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/slices/02_std/why3shapes.gz b/creusot/tests/should_succeed/slices/02_std/why3shapes.gz
index 3da06821c..6aae85d5b 100644
Binary files a/creusot/tests/should_succeed/slices/02_std/why3shapes.gz and b/creusot/tests/should_succeed/slices/02_std/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/sparse_array/why3session.xml b/creusot/tests/should_succeed/sparse_array/why3session.xml
index 22d3b951f..eb761eb3d 100644
--- a/creusot/tests/should_succeed/sparse_array/why3session.xml
+++ b/creusot/tests/should_succeed/sparse_array/why3session.xml
@@ -2,40 +2,40 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="CVC4" version="1.8" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="5" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<file format="mlcfg" proved="true">
+<prover id="4" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
+<file format="mlcfg">
 <path name=".."/><path name="sparse_array.mlcfg"/>
 <theory name="SparseArray_Impl2_Get" proved="true">
  <goal name="get&#39;vc" expl="VC for get" proved="true">
- <proof prover="3"><result status="valid" time="0.119879" steps="23547"/></proof>
+ <proof prover="3"><result status="valid" time="0.119879" steps="22753"/></proof>
  </goal>
 </theory>
-<theory name="SparseArray_Impl2_LemmaPermutation_Impl" proved="true">
- <goal name="lemma_permutation&#39;vc" expl="VC for lemma_permutation" proved="true">
- <transf name="split_vc" proved="true" >
-  <goal name="lemma_permutation&#39;vc.0" expl="postcondition" proved="true">
-  <transf name="use_th" proved="true" arg1="map.MapInjection">
-   <goal name="lemma_permutation&#39;vc.0.0" expl="postcondition" proved="true">
-   <transf name="pose" proved="true" arg1="f" arg2="(fun k -&gt; to_int (get1 (shallow_model1 (sparse_back self)) k))">
-    <goal name="lemma_permutation&#39;vc.0.0.0" expl="postcondition" proved="true">
-    <transf name="assert" proved="true" arg1="(surjective f (sparse_n self))">
-     <goal name="lemma_permutation&#39;vc.0.0.0.0" expl="asserted formula" proved="true">
-     <proof prover="1"><result status="valid" time="0.130197" steps="27133"/></proof>
+<theory name="SparseArray_Impl2_LemmaPermutation_Impl">
+ <goal name="lemma_permutation&#39;vc" expl="VC for lemma_permutation">
+ <transf name="split_vc" >
+  <goal name="lemma_permutation&#39;vc.0" expl="postcondition">
+  <transf name="use_th" arg1="map.MapInjection">
+   <goal name="lemma_permutation&#39;vc.0.0" expl="postcondition">
+   <transf name="pose" arg1="f" arg2="(fun k -&gt; to_int (get1 (shallow_model1 (sparse_back self)) k))">
+    <goal name="lemma_permutation&#39;vc.0.0.0" expl="postcondition">
+    <transf name="assert" arg1="(surjective f (sparse_n self))">
+     <goal name="lemma_permutation&#39;vc.0.0.0.0" expl="asserted formula">
+     <proof prover="1" obsolete="true"><result status="valid" time="0.130197" steps="27133"/></proof>
      </goal>
      <goal name="lemma_permutation&#39;vc.0.0.0.1" expl="postcondition" proved="true">
      <transf name="assert" proved="true" arg1="(exists k. 0 &lt;= k &lt; sparse_n self /\ (f k) = i)">
       <goal name="lemma_permutation&#39;vc.0.0.0.1.0" expl="asserted formula" proved="true">
       <transf name="unfold" proved="true" arg1="surjective" arg2="in" arg3="h1">
        <goal name="lemma_permutation&#39;vc.0.0.0.1.0.0" expl="asserted formula" proved="true">
-       <proof prover="5"><result status="valid" time="0.205093" steps="2161"/></proof>
+       <proof prover="4"><result status="valid" time="0.205093" steps="2160"/></proof>
        </goal>
       </transf>
       </goal>
       <goal name="lemma_permutation&#39;vc.0.0.0.1.1" expl="postcondition" proved="true">
-      <proof prover="3"><result status="valid" time="0.094333" steps="12169"/></proof>
+      <proof prover="3"><result status="valid" time="0.094333" steps="12069"/></proof>
       </goal>
      </transf>
      </goal>
@@ -52,95 +52,95 @@
  <goal name="set&#39;vc" expl="VC for set" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="set&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.317095" steps="17955"/></proof>
+  <proof prover="3"><result status="valid" time="0.049523" steps="16806"/></proof>
   </goal>
   <goal name="set&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.165675" steps="15819"/></proof>
+  <proof prover="3"><result status="valid" time="0.036540" steps="14670"/></proof>
   </goal>
   <goal name="set&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.093846" steps="15824"/></proof>
+  <proof prover="3"><result status="valid" time="0.093846" steps="14675"/></proof>
   </goal>
   <goal name="set&#39;vc.3" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.098301" steps="14791"/></proof>
+  <proof prover="3"><result status="valid" time="0.098301" steps="13970"/></proof>
   </goal>
   <goal name="set&#39;vc.4" expl="type invariant" proved="true">
-  <proof prover="3"><result status="valid" time="0.126567" steps="16136"/></proof>
+  <proof prover="3"><result status="valid" time="0.126567" steps="15315"/></proof>
   </goal>
   <goal name="set&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="5"><result status="valid" time="0.024183" steps="289"/></proof>
+  <proof prover="4"><result status="valid" time="0.024183" steps="289"/></proof>
   </goal>
   <goal name="set&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.109230" steps="19370"/></proof>
+  <proof prover="3"><result status="valid" time="0.109230" steps="17998"/></proof>
   </goal>
   <goal name="set&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.193378" steps="19371"/></proof>
+  <proof prover="3"><result status="valid" time="0.048217" steps="17999"/></proof>
   </goal>
   <goal name="set&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.140696" steps="22403"/></proof>
+  <proof prover="3"><result status="valid" time="0.140696" steps="21359"/></proof>
   </goal>
   <goal name="set&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.142968" steps="19605"/></proof>
+  <proof prover="3"><result status="valid" time="0.142968" steps="18561"/></proof>
   </goal>
   <goal name="set&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.108040" steps="19611"/></proof>
+  <proof prover="3"><result status="valid" time="0.108040" steps="18567"/></proof>
   </goal>
   <goal name="set&#39;vc.11" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.517403" steps="783328"/></proof>
+  <proof prover="2"><result status="valid" time="0.143120" steps="656873"/></proof>
   </goal>
   <goal name="set&#39;vc.12" expl="assertion" proved="true">
-  <proof prover="3"><result status="valid" time="0.238761" steps="28298"/></proof>
+  <proof prover="3"><result status="valid" time="0.089553" steps="26803"/></proof>
   </goal>
   <goal name="set&#39;vc.13" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.213043" steps="23305"/></proof>
+  <proof prover="3"><result status="valid" time="0.070125" steps="22261"/></proof>
   </goal>
   <goal name="set&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.238189" steps="20332"/></proof>
+  <proof prover="3"><result status="valid" time="0.050465" steps="19288"/></proof>
   </goal>
   <goal name="set&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.160266" steps="20337"/></proof>
+  <proof prover="3"><result status="valid" time="0.160266" steps="19293"/></proof>
   </goal>
   <goal name="set&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.244901" steps="24754"/></proof>
+  <proof prover="3"><result status="valid" time="0.074932" steps="23710"/></proof>
   </goal>
   <goal name="set&#39;vc.17" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.164054" steps="20848"/></proof>
+  <proof prover="3"><result status="valid" time="0.164054" steps="19804"/></proof>
   </goal>
   <goal name="set&#39;vc.18" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.109818" steps="20863"/></proof>
+  <proof prover="3"><result status="valid" time="0.109818" steps="19819"/></proof>
   </goal>
   <goal name="set&#39;vc.19" expl="integer overflow" proved="true">
-  <proof prover="3"><result status="valid" time="0.255573" steps="29385"/></proof>
+  <proof prover="3"><result status="valid" time="0.094717" steps="28393"/></proof>
   </goal>
   <goal name="set&#39;vc.20" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.861516" steps="1289397"/></proof>
+  <proof prover="2"><result status="valid" time="0.368720" steps="1350053"/></proof>
   </goal>
   <goal name="set&#39;vc.21" expl="postcondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.301371" steps="29236"/></proof>
+  <proof prover="3"><result status="valid" time="0.087245" steps="28192"/></proof>
   </goal>
   <goal name="set&#39;vc.22" expl="postcondition" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="set&#39;vc.22.0" expl="postcondition" proved="true">
-   <proof prover="3"><result status="valid" time="0.267856" steps="38898"/></proof>
+   <proof prover="3"><result status="valid" time="0.130441" steps="36884"/></proof>
    </goal>
    <goal name="set&#39;vc.22.1" expl="postcondition" proved="true">
-   <proof prover="3"><result status="valid" time="0.439165" steps="65990"/></proof>
+   <proof prover="3"><result status="valid" time="0.251558" steps="66943"/></proof>
    </goal>
   </transf>
   </goal>
   <goal name="set&#39;vc.23" expl="postcondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.376107" steps="528799"/></proof>
+  <proof prover="2"><result status="valid" time="0.094411" steps="495047"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="SparseArray_Create" proved="true">
  <goal name="create&#39;vc" expl="VC for create" proved="true">
- <proof prover="3"><result status="valid" time="0.405832" steps="35342"/></proof>
+ <proof prover="3"><result status="valid" time="0.161894" steps="61004"/></proof>
  </goal>
 </theory>
 <theory name="SparseArray_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="0"><result status="valid" time="0.328671" steps="410665"/></proof>
+ <proof prover="2"><result status="valid" time="0.084133" steps="429716"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/sparse_array/why3shapes.gz b/creusot/tests/should_succeed/sparse_array/why3shapes.gz
index ab0eac4e7..0b93af0a3 100644
Binary files a/creusot/tests/should_succeed/sparse_array/why3shapes.gz and b/creusot/tests/should_succeed/sparse_array/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/specification/division/why3session.xml b/creusot/tests/should_succeed/specification/division/why3session.xml
index f43b14509..f03c368a6 100644
--- a/creusot/tests/should_succeed/specification/division/why3session.xml
+++ b/creusot/tests/should_succeed/specification/division/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="division.mlcfg"/>
 <theory name="Division_Divide" proved="true">
  <goal name="divide&#39;vc" expl="VC for divide" proved="true">
- <proof prover="1"><result status="valid" time="0.008165" steps="59"/></proof>
+ <proof prover="0"><result status="valid" time="0.008165" steps="59"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/specification/forall/why3session.xml b/creusot/tests/should_succeed/specification/forall/why3session.xml
index f8454789d..9334ba099 100644
--- a/creusot/tests/should_succeed/specification/forall/why3session.xml
+++ b/creusot/tests/should_succeed/specification/forall/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="forall.mlcfg"/>
 <theory name="Forall_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.006964" steps="2"/></proof>
+ <proof prover="0"><result status="valid" time="0.006964" steps="2"/></proof>
  </goal>
 </theory>
 <theory name="Forall_Omg_Impl" proved="true">
  <goal name="omg&#39;vc" expl="VC for omg" proved="true">
- <proof prover="1"><result status="valid" time="0.005485" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.005485" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/specification/logic_call/why3session.xml b/creusot/tests/should_succeed/specification/logic_call/why3session.xml
index 74a416b52..5c642dfa8 100644
--- a/creusot/tests/should_succeed/specification/logic_call/why3session.xml
+++ b/creusot/tests/should_succeed/specification/logic_call/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="logic_call.mlcfg"/>
 <theory name="LogicCall_Dummy" proved="true">
  <goal name="dummy&#39;vc" expl="VC for dummy" proved="true">
- <proof prover="1"><result status="valid" time="0.006199" steps="8"/></proof>
+ <proof prover="0"><result status="valid" time="0.006199" steps="8"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/specification/logic_functions/why3session.xml b/creusot/tests/should_succeed/specification/logic_functions/why3session.xml
index 31fd57ec1..f169c0e85 100644
--- a/creusot/tests/should_succeed/specification/logic_functions/why3session.xml
+++ b/creusot/tests/should_succeed/specification/logic_functions/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="logic_functions.mlcfg"/>
 <theory name="LogicFunctions_UseLogic" proved="true">
  <goal name="use_logic&#39;vc" expl="VC for use_logic" proved="true">
- <proof prover="1"><result status="valid" time="0.004230" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.004230" steps="0"/></proof>
  </goal>
 </theory>
 <theory name="LogicFunctions_UseLogicPearlite" proved="true">
  <goal name="use_logic_pearlite&#39;vc" expl="VC for use_logic_pearlite" proved="true">
- <proof prover="1"><result status="valid" time="0.005307" steps="2"/></proof>
+ <proof prover="0"><result status="valid" time="0.005307" steps="2"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/specification/trusted/why3session.xml b/creusot/tests/should_succeed/specification/trusted/why3session.xml
index e7ba70514..66d895702 100644
--- a/creusot/tests/should_succeed/specification/trusted/why3session.xml
+++ b/creusot/tests/should_succeed/specification/trusted/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="trusted.mlcfg"/>
 <theory name="Trusted_VictimOfLie" proved="true">
  <goal name="victim_of_lie&#39;vc" expl="VC for victim_of_lie" proved="true">
- <proof prover="1"><result status="valid" time="0.005508" steps="2"/></proof>
+ <proof prover="0"><result status="valid" time="0.005508" steps="2"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/sum/why3session.xml b/creusot/tests/should_succeed/sum/why3session.xml
index bfa8cce7c..1be18dcbc 100644
--- a/creusot/tests/should_succeed/sum/why3session.xml
+++ b/creusot/tests/should_succeed/sum/why3session.xml
@@ -4,38 +4,39 @@
 <why3session shape_version="6">
 <prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="4" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="sum.mlcfg"/>
 <theory name="Sum_SumFirstN" proved="true">
  <goal name="sum_first_n&#39;vc" expl="VC for sum_first_n" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="sum_first_n&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.013914" steps="46455"/></proof>
+  <proof prover="3"><result status="valid" time="0.015236" steps="42521"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.106520" steps="19"/></proof>
+  <proof prover="4"><result status="valid" time="0.106520" steps="19"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.007380" steps="16"/></proof>
+  <proof prover="4"><result status="valid" time="0.007380" steps="16"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.008401" steps="16"/></proof>
+  <proof prover="4"><result status="valid" time="0.008401" steps="16"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.008354" steps="3858"/></proof>
+  <proof prover="3"><result status="valid" time="0.009981" steps="4034"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.5" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.008896" steps="37"/></proof>
+  <proof prover="4"><result status="valid" time="0.008896" steps="37"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.6" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.014020" steps="215"/></proof>
+  <proof prover="4"><result status="valid" time="0.014020" steps="214"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.007377" steps="101"/></proof>
+  <proof prover="4"><result status="valid" time="0.007377" steps="101"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.8" expl="postcondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.405841" steps="14361"/></proof>
+  <proof prover="4"><result status="valid" time="0.405841" steps="14356"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.9" expl="integer overflow" proved="true">
   <transf name="split_vc" proved="true" >
@@ -49,7 +50,7 @@
      <goal name="sum_first_n&#39;vc.9.0.0.1" expl="VC for sum_first_n" proved="true">
      <transf name="inline_goal" proved="true" >
       <goal name="sum_first_n&#39;vc.9.0.0.1.0" expl="VC for sum_first_n" proved="true">
-      <proof prover="2" timelimit="30" memlimit="4000"><result status="valid" time="0.251319" steps="1076869"/></proof>
+      <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="0.854840" steps="2745056"/></proof>
       </goal>
      </transf>
      </goal>
@@ -60,18 +61,18 @@
   </transf>
   </goal>
   <goal name="sum_first_n&#39;vc.10" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.108026" steps="11558"/></proof>
+  <proof prover="1"><result status="valid" time="0.108026" steps="11302"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.11" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.173264" steps="4705"/></proof>
+  <proof prover="4"><result status="valid" time="0.173264" steps="4708"/></proof>
   </goal>
   <goal name="sum_first_n&#39;vc.12" expl="loop invariant preservation" proved="true">
   <transf name="assert" proved="true" arg1="(to_int i = length (inner produced))">
    <goal name="sum_first_n&#39;vc.12.0" expl="asserted formula" proved="true">
-   <proof prover="0"><result status="valid" time="0.100016" steps="1240"/></proof>
+   <proof prover="4"><result status="valid" time="0.100016" steps="1241"/></proof>
    </goal>
    <goal name="sum_first_n&#39;vc.12.1" expl="loop invariant preservation" proved="true">
-   <proof prover="0"><result status="valid" time="0.235500" steps="3565"/></proof>
+   <proof prover="4"><result status="valid" time="0.235500" steps="3563"/></proof>
    </goal>
   </transf>
   </goal>
diff --git a/creusot/tests/should_succeed/sum/why3shapes.gz b/creusot/tests/should_succeed/sum/why3shapes.gz
index 345b44b36..f466c413c 100644
Binary files a/creusot/tests/should_succeed/sum/why3shapes.gz and b/creusot/tests/should_succeed/sum/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/sum_of_odds/why3session.xml b/creusot/tests/should_succeed/sum_of_odds/why3session.xml
index 851f75bef..ae9d697fb 100644
--- a/creusot/tests/should_succeed/sum_of_odds/why3session.xml
+++ b/creusot/tests/should_succeed/sum_of_odds/why3session.xml
@@ -2,8 +2,9 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="2" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="sum_of_odds.mlcfg"/>
 <theory name="SumOfOdds_SumOfOdd_Impl" proved="true">
@@ -13,53 +14,53 @@
 </theory>
 <theory name="SumOfOdds_SumOfOddIsSqr_Impl" proved="true">
  <goal name="sum_of_odd_is_sqr&#39;vc" expl="VC for sum_of_odd_is_sqr" proved="true">
- <proof prover="0"><result status="valid" time="0.008268" steps="1693"/></proof>
+ <proof prover="1"><result status="valid" time="0.010615" steps="1543"/></proof>
  </goal>
 </theory>
 <theory name="SumOfOdds_ComputeSumOfOdd" proved="true">
  <goal name="compute_sum_of_odd&#39;vc" expl="VC for compute_sum_of_odd" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="compute_sum_of_odd&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009885" steps="8"/></proof>
+  <proof prover="3"><result status="valid" time="0.009885" steps="8"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.019646" steps="15"/></proof>
+  <proof prover="3"><result status="valid" time="0.019646" steps="15"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.2" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.011411" steps="16"/></proof>
+  <proof prover="3"><result status="valid" time="0.011411" steps="16"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.3" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.014429" steps="25"/></proof>
+  <proof prover="3"><result status="valid" time="0.014429" steps="25"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.018927" steps="96"/></proof>
+  <proof prover="3"><result status="valid" time="0.018927" steps="95"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.010425" steps="46"/></proof>
+  <proof prover="3"><result status="valid" time="0.010425" steps="45"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.6" expl="postcondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.048413" steps="433"/></proof>
+  <proof prover="3"><result status="valid" time="0.048413" steps="433"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.7" expl="assertion" proved="true">
-  <proof prover="2"><result status="valid" time="0.007018" steps="48"/></proof>
+  <proof prover="3"><result status="valid" time="0.007018" steps="48"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.8" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.093643" steps="1061"/></proof>
+  <proof prover="3"><result status="valid" time="0.093643" steps="1060"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.9" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.027777" steps="217"/></proof>
+  <proof prover="3"><result status="valid" time="0.027777" steps="216"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.10" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.238716" steps="2953"/></proof>
+  <proof prover="3"><result status="valid" time="0.113176" steps="2956"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.11" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.037591" steps="94"/></proof>
+  <proof prover="3"><result status="valid" time="0.037591" steps="93"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.12" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.375992" steps="3996"/></proof>
+  <proof prover="3"><result status="valid" time="0.158851" steps="3995"/></proof>
   </goal>
   <goal name="compute_sum_of_odd&#39;vc.13" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.070890" steps="573"/></proof>
+  <proof prover="3"><result status="valid" time="0.070890" steps="572"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/sum_of_odds/why3shapes.gz b/creusot/tests/should_succeed/sum_of_odds/why3shapes.gz
index 14e25fd2d..cbe4d366d 100644
Binary files a/creusot/tests/should_succeed/sum_of_odds/why3shapes.gz and b/creusot/tests/should_succeed/sum_of_odds/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/swap_borrows/why3session.xml b/creusot/tests/should_succeed/swap_borrows/why3session.xml
index cfdf672bf..1c6808ca9 100644
--- a/creusot/tests/should_succeed/swap_borrows/why3session.xml
+++ b/creusot/tests/should_succeed/swap_borrows/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="swap_borrows.mlcfg"/>
 <theory name="SwapBorrows_Swap" proved="true">
  <goal name="swap&#39;vc" expl="VC for swap" proved="true">
- <proof prover="1"><result status="valid" time="0.006682" steps="9"/></proof>
+ <proof prover="0"><result status="valid" time="0.006682" steps="9"/></proof>
  </goal>
 </theory>
 <theory name="SwapBorrows_F" proved="true">
  <goal name="f&#39;vc" expl="VC for f" proved="true">
- <proof prover="1"><result status="valid" time="0.017480" steps="100"/></proof>
+ <proof prover="0"><result status="valid" time="0.017480" steps="100"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/syntax/02_operators/why3session.xml b/creusot/tests/should_succeed/syntax/02_operators/why3session.xml
index d4359928e..ef97012d8 100644
--- a/creusot/tests/should_succeed/syntax/02_operators/why3session.xml
+++ b/creusot/tests/should_succeed/syntax/02_operators/why3session.xml
@@ -3,8 +3,8 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="2" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="02_operators.mlcfg"/>
 <theory name="C02Operators_Division" proved="true">
@@ -29,7 +29,7 @@
 </theory>
 <theory name="C02Operators_Sub" proved="true">
  <goal name="sub&#39;vc" expl="VC for sub" proved="true">
- <proof prover="1"><result status="valid" time="0.007647" steps="1619"/></proof>
+ <proof prover="3"><result status="valid" time="0.011202" steps="1611"/></proof>
  </goal>
 </theory>
 <theory name="C02Operators_Expression" proved="true">
@@ -44,7 +44,7 @@
 </theory>
 <theory name="C02Operators_PrimitiveComparison" proved="true">
  <goal name="primitive_comparison&#39;vc" expl="VC for primitive_comparison" proved="true">
- <proof prover="1"><result status="valid" time="0.009421" steps="106"/></proof>
+ <proof prover="3"><result status="valid" time="0.010620" steps="106"/></proof>
  </goal>
 </theory>
 <theory name="C02Operators_BoolEq" proved="true">
diff --git a/creusot/tests/should_succeed/syntax/06_logic_function_contracts/why3session.xml b/creusot/tests/should_succeed/syntax/06_logic_function_contracts/why3session.xml
index 6508257e7..c2fa7ab82 100644
--- a/creusot/tests/should_succeed/syntax/06_logic_function_contracts/why3session.xml
+++ b/creusot/tests/should_succeed/syntax/06_logic_function_contracts/why3session.xml
@@ -2,18 +2,19 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="06_logic_function_contracts.mlcfg"/>
 <theory name="C06LogicFunctionContracts_Sum_Impl" proved="true">
  <goal name="sum&#39;vc" expl="VC for sum" proved="true">
- <proof prover="0"><result status="valid" time="0.012757" steps="41138"/></proof>
+ <proof prover="2"><result status="valid" time="0.019315" steps="37880"/></proof>
  </goal>
 </theory>
 <theory name="C06LogicFunctionContracts_AllZero_Impl" proved="true">
  <goal name="all_zero&#39;vc" expl="VC for all_zero" proved="true">
- <proof prover="1"><result status="valid" time="0.008419" steps="15"/></proof>
+ <proof prover="3"><result status="valid" time="0.008419" steps="15"/></proof>
  </goal>
 </theory>
 <theory name="C06LogicFunctionContracts_Stupid_Impl" proved="true">
diff --git a/creusot/tests/should_succeed/syntax/06_logic_function_contracts/why3shapes.gz b/creusot/tests/should_succeed/syntax/06_logic_function_contracts/why3shapes.gz
index fcd3aae4f..c74f2acb9 100644
Binary files a/creusot/tests/should_succeed/syntax/06_logic_function_contracts/why3shapes.gz and b/creusot/tests/should_succeed/syntax/06_logic_function_contracts/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/syntax/09_maintains/why3session.xml b/creusot/tests/should_succeed/syntax/09_maintains/why3session.xml
index 2ac0f7371..7c9316231 100644
--- a/creusot/tests/should_succeed/syntax/09_maintains/why3session.xml
+++ b/creusot/tests/should_succeed/syntax/09_maintains/why3session.xml
@@ -2,9 +2,9 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="2" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="09_maintains.mlcfg"/>
 <theory name="C09Maintains_Test1" proved="true">
@@ -19,7 +19,7 @@
 </theory>
 <theory name="C09Maintains_Test3" proved="true">
  <goal name="test_3&#39;vc" expl="VC for test_3" proved="true">
- <proof prover="0"><result status="valid" time="0.006890" steps="588"/></proof>
+ <proof prover="3"><result status="valid" time="0.011029" steps="588"/></proof>
  </goal>
 </theory>
 <theory name="C09Maintains_Test5" proved="true">
diff --git a/creusot/tests/should_succeed/syntax/11_array_types/why3session.xml b/creusot/tests/should_succeed/syntax/11_array_types/why3session.xml
index 36cbb722a..f98e5c9b6 100644
--- a/creusot/tests/should_succeed/syntax/11_array_types/why3session.xml
+++ b/creusot/tests/should_succeed/syntax/11_array_types/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="11_array_types.mlcfg"/>
 <theory name="C11ArrayTypes_Omg" proved="true">
  <goal name="omg&#39;vc" expl="VC for omg" proved="true">
- <proof prover="0"><result status="valid" time="0.007404" steps="23"/></proof>
+ <proof prover="1"><result status="valid" time="0.007404" steps="23"/></proof>
  </goal>
 </theory>
 <theory name="C11ArrayTypes_CallOmg" proved="true">
  <goal name="call_omg&#39;vc" expl="VC for call_omg" proved="true">
- <proof prover="0"><result status="valid" time="0.007545" steps="27"/></proof>
+ <proof prover="1"><result status="valid" time="0.007545" steps="27"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/syntax/11_array_types/why3shapes.gz b/creusot/tests/should_succeed/syntax/11_array_types/why3shapes.gz
index f5066d0ec..c3ff302a4 100644
Binary files a/creusot/tests/should_succeed/syntax/11_array_types/why3shapes.gz and b/creusot/tests/should_succeed/syntax/11_array_types/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/syntax/12_ghost_code/why3session.xml b/creusot/tests/should_succeed/syntax/12_ghost_code/why3session.xml
index d39f4ff35..b1871b20b 100644
--- a/creusot/tests/should_succeed/syntax/12_ghost_code/why3session.xml
+++ b/creusot/tests/should_succeed/syntax/12_ghost_code/why3session.xml
@@ -3,7 +3,7 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="12_ghost_code.mlcfg"/>
 <theory name="C12GhostCode_GhostIsCopy" proved="true">
@@ -13,7 +13,7 @@
 </theory>
 <theory name="C12GhostCode_GhostCheck" proved="true">
  <goal name="ghost_check&#39;vc" expl="VC for ghost_check" proved="true">
- <proof prover="1"><result status="valid" time="0.014735" steps="60"/></proof>
+ <proof prover="2"><result status="valid" time="0.014735" steps="60"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/syntax/12_ghost_code/why3shapes.gz b/creusot/tests/should_succeed/syntax/12_ghost_code/why3shapes.gz
index 69b0082f9..679b70d37 100644
Binary files a/creusot/tests/should_succeed/syntax/12_ghost_code/why3shapes.gz and b/creusot/tests/should_succeed/syntax/12_ghost_code/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/syntax/13_vec_macro/why3session.xml b/creusot/tests/should_succeed/syntax/13_vec_macro/why3session.xml
index 058e693b7..3116ab6db 100644
--- a/creusot/tests/should_succeed/syntax/13_vec_macro/why3session.xml
+++ b/creusot/tests/should_succeed/syntax/13_vec_macro/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="3" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="13_vec_macro.mlcfg"/>
 <theory name="C13VecMacro_X" proved="true">
  <goal name="x&#39;vc" expl="VC for x" proved="true">
- <proof prover="3"><result status="valid" time="0.012870" steps="117"/></proof>
+ <proof prover="0"><result status="valid" time="0.012870" steps="117"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/syntax/13_vec_macro/why3shapes.gz b/creusot/tests/should_succeed/syntax/13_vec_macro/why3shapes.gz
index 5e7503b75..6b7d909af 100644
Binary files a/creusot/tests/should_succeed/syntax/13_vec_macro/why3shapes.gz and b/creusot/tests/should_succeed/syntax/13_vec_macro/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/syntax/derive_macros/why3session.xml b/creusot/tests/should_succeed/syntax/derive_macros/why3session.xml
index 9770112e8..ffb4def5a 100644
--- a/creusot/tests/should_succeed/syntax/derive_macros/why3session.xml
+++ b/creusot/tests/should_succeed/syntax/derive_macros/why3session.xml
@@ -3,7 +3,7 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="derive_macros.mlcfg"/>
 <theory name="DeriveMacros_Impl2_Clone" proved="true">
@@ -18,7 +18,7 @@
 </theory>
 <theory name="DeriveMacros_Impl4_Clone" proved="true">
  <goal name="clone&#39;&#39;vc" expl="VC for clone&#39;" proved="true">
- <proof prover="1"><result status="valid" time="0.009828" steps="11306"/></proof>
+ <proof prover="2"><result status="valid" time="0.012907" steps="9877"/></proof>
  </goal>
 </theory>
 <theory name="DeriveMacros_Impl5_Eq" proved="true">
@@ -33,7 +33,7 @@
 </theory>
 <theory name="DeriveMacros_Impl4" proved="true">
  <goal name="clone&#39;_refn" proved="true">
- <proof prover="1"><result status="valid" time="0.007195" steps="433"/></proof>
+ <proof prover="2"><result status="valid" time="0.010641" steps="433"/></proof>
  </goal>
 </theory>
 <theory name="DeriveMacros_Impl3" proved="true">
diff --git a/creusot/tests/should_succeed/take_first_mut/why3session.xml b/creusot/tests/should_succeed/take_first_mut/why3session.xml
index efe891a4d..b15625318 100644
--- a/creusot/tests/should_succeed/take_first_mut/why3session.xml
+++ b/creusot/tests/should_succeed/take_first_mut/why3session.xml
@@ -7,7 +7,7 @@
 <path name=".."/><path name="take_first_mut.mlcfg"/>
 <theory name="TakeFirstMut_TakeFirstMut" proved="true">
  <goal name="take_first_mut&#39;vc" expl="VC for take_first_mut" proved="true">
- <proof prover="1"><result status="valid" time="0.553322" steps="84825"/></proof>
+ <proof prover="1"><result status="valid" time="0.218773" steps="89062"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/take_first_mut/why3shapes.gz b/creusot/tests/should_succeed/take_first_mut/why3shapes.gz
index e3a3c70d2..6a0a7abcf 100644
Binary files a/creusot/tests/should_succeed/take_first_mut/why3shapes.gz and b/creusot/tests/should_succeed/take_first_mut/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/traits/02/why3session.xml b/creusot/tests/should_succeed/traits/02/why3session.xml
index e58a464ab..69068c8ae 100644
--- a/creusot/tests/should_succeed/traits/02/why3session.xml
+++ b/creusot/tests/should_succeed/traits/02/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="02.mlcfg"/>
 <theory name="C02_Omg" proved="true">
  <goal name="omg&#39;vc" expl="VC for omg" proved="true">
- <proof prover="1"><result status="valid" time="0.004445" steps="4"/></proof>
+ <proof prover="0"><result status="valid" time="0.004445" steps="4"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/traits/12_default_method/why3session.xml b/creusot/tests/should_succeed/traits/12_default_method/why3session.xml
index 2ba371719..327f395a9 100644
--- a/creusot/tests/should_succeed/traits/12_default_method/why3session.xml
+++ b/creusot/tests/should_succeed/traits/12_default_method/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="12_default_method.mlcfg"/>
 <theory name="C12DefaultMethod_T_Default" proved="true">
  <goal name="default&#39;vc" expl="VC for default" proved="true">
- <proof prover="1"><result status="valid" time="0.006114" steps="8"/></proof>
+ <proof prover="0"><result status="valid" time="0.006114" steps="8"/></proof>
  </goal>
 </theory>
 <theory name="C12DefaultMethod_ShouldUseImpl" proved="true">
  <goal name="should_use_impl&#39;vc" expl="VC for should_use_impl" proved="true">
- <proof prover="1"><result status="valid" time="0.006043" steps="4"/></proof>
+ <proof prover="0"><result status="valid" time="0.006043" steps="4"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/traits/13_assoc_types/why3session.xml b/creusot/tests/should_succeed/traits/13_assoc_types/why3session.xml
index cad38239b..0116e0197 100644
--- a/creusot/tests/should_succeed/traits/13_assoc_types/why3session.xml
+++ b/creusot/tests/should_succeed/traits/13_assoc_types/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="13_assoc_types.mlcfg"/>
 <theory name="C13AssocTypes_Impl0_Model" proved="true">
  <goal name="model&#39;vc" expl="VC for model" proved="true">
- <proof prover="0"><result status="valid" time="0.007763" steps="2"/></proof>
+ <proof prover="1"><result status="valid" time="0.007763" steps="2"/></proof>
  </goal>
 </theory>
 <theory name="C13AssocTypes_Impl0" proved="true">
  <goal name="model_refn" proved="true">
- <proof prover="0"><result status="valid" time="0.007899" steps="0"/></proof>
+ <proof prover="1"><result status="valid" time="0.007899" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/traits/16_impl_cloning/why3session.xml b/creusot/tests/should_succeed/traits/16_impl_cloning/why3session.xml
index 226d56a98..724789b50 100644
--- a/creusot/tests/should_succeed/traits/16_impl_cloning/why3session.xml
+++ b/creusot/tests/should_succeed/traits/16_impl_cloning/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="16_impl_cloning.mlcfg"/>
 <theory name="C16ImplCloning_Test" proved="true">
  <goal name="test&#39;vc" expl="VC for test" proved="true">
- <proof prover="1"><result status="valid" time="0.007470" steps="8"/></proof>
+ <proof prover="0"><result status="valid" time="0.007470" steps="8"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/traits/16_impl_cloning/why3shapes.gz b/creusot/tests/should_succeed/traits/16_impl_cloning/why3shapes.gz
index 3492c69cb..549b88642 100644
Binary files a/creusot/tests/should_succeed/traits/16_impl_cloning/why3shapes.gz and b/creusot/tests/should_succeed/traits/16_impl_cloning/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/traits/18_trait_laws/why3session.xml b/creusot/tests/should_succeed/traits/18_trait_laws/why3session.xml
index b634bb7f6..aa25bfb00 100644
--- a/creusot/tests/should_succeed/traits/18_trait_laws/why3session.xml
+++ b/creusot/tests/should_succeed/traits/18_trait_laws/why3session.xml
@@ -2,8 +2,8 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="18_trait_laws.mlcfg"/>
 <theory name="C18TraitLaws_UsesOp_Impl" proved="true">
@@ -13,7 +13,7 @@
 </theory>
 <theory name="C18TraitLaws_Impl0_Reflexive_Impl" proved="true">
  <goal name="reflexive&#39;vc" expl="VC for reflexive" proved="true">
- <proof prover="0"><result status="valid" time="0.007368" steps="6"/></proof>
+ <proof prover="2"><result status="valid" time="0.010607" steps="6"/></proof>
  </goal>
 </theory>
 <theory name="C18TraitLaws_ImplLaws_Impl" proved="true">
diff --git a/creusot/tests/should_succeed/type_invariants/generated/why3session.xml b/creusot/tests/should_succeed/type_invariants/generated/why3session.xml
index 4834550de..374444741 100644
--- a/creusot/tests/should_succeed/type_invariants/generated/why3session.xml
+++ b/creusot/tests/should_succeed/type_invariants/generated/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="generated.mlcfg"/>
 <theory name="Generated_UseFoo" proved="true">
  <goal name="use_foo&#39;vc" expl="VC for use_foo" proved="true">
- <proof prover="0"><result status="valid" time="0.007458" steps="5"/></proof>
+ <proof prover="1"><result status="valid" time="0.007458" steps="5"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/type_invariants/non_zero/why3session.xml b/creusot/tests/should_succeed/type_invariants/non_zero/why3session.xml
index a5abb58de..027b856ed 100644
--- a/creusot/tests/should_succeed/type_invariants/non_zero/why3session.xml
+++ b/creusot/tests/should_succeed/type_invariants/non_zero/why3session.xml
@@ -2,8 +2,8 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="non_zero.mlcfg"/>
 <theory name="NonZero_Impl1_New" proved="true">
@@ -18,7 +18,7 @@
 </theory>
 <theory name="NonZero_Impl1_SubPreTrans_Impl" proved="true">
  <goal name="sub_pre_trans&#39;vc" expl="VC for sub_pre_trans" proved="true">
- <proof prover="0"><result status="valid" time="0.010971" steps="2303"/></proof>
+ <proof prover="2"><result status="valid" time="0.012607" steps="2292"/></proof>
  </goal>
 </theory>
 <theory name="NonZero_Impl1_Sub" proved="true">
diff --git a/creusot/tests/should_succeed/type_invariants/quant/why3session.xml b/creusot/tests/should_succeed/type_invariants/quant/why3session.xml
index 2a92ba966..5438d54dd 100644
--- a/creusot/tests/should_succeed/type_invariants/quant/why3session.xml
+++ b/creusot/tests/should_succeed/type_invariants/quant/why3session.xml
@@ -3,7 +3,7 @@
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
 <prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="quant.mlcfg"/>
 <theory name="Quant_Forall_Impl" proved="true">
@@ -13,7 +13,7 @@
 </theory>
 <theory name="Quant_Exists_Impl" proved="true">
  <goal name="exists&#39;&#39;vc" expl="VC for exists&#39;" proved="true">
- <proof prover="2"><result status="valid" time="0.008010" steps="430"/></proof>
+ <proof prover="1"><result status="valid" time="0.012453" steps="409"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/type_invariants/type_invariants/why3session.xml b/creusot/tests/should_succeed/type_invariants/type_invariants/why3session.xml
index 613aedc3f..7a558ad90 100644
--- a/creusot/tests/should_succeed/type_invariants/type_invariants/why3session.xml
+++ b/creusot/tests/should_succeed/type_invariants/type_invariants/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="type_invariants.mlcfg"/>
 <theory name="TypeInvariants_Id" proved="true">
  <goal name="id&#39;vc" expl="VC for id" proved="true">
- <proof prover="1"><result status="valid" time="0.004426" steps="0"/></proof>
+ <proof prover="0"><result status="valid" time="0.004426" steps="0"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/type_invariants/vec_inv/why3session.xml b/creusot/tests/should_succeed/type_invariants/vec_inv/why3session.xml
index dc17e0f11..92135c671 100644
--- a/creusot/tests/should_succeed/type_invariants/vec_inv/why3session.xml
+++ b/creusot/tests/should_succeed/type_invariants/vec_inv/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="vec_inv.mlcfg"/>
 <theory name="VecInv_Vec" proved="true">
  <goal name="vec&#39;vc" expl="VC for vec" proved="true">
- <proof prover="0"><result status="valid" time="0.036238" steps="58"/></proof>
+ <proof prover="1"><result status="valid" time="0.036238" steps="58"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/type_invariants/vec_inv/why3shapes.gz b/creusot/tests/should_succeed/type_invariants/vec_inv/why3shapes.gz
index 51da37f82..db78d5985 100644
Binary files a/creusot/tests/should_succeed/type_invariants/vec_inv/why3shapes.gz and b/creusot/tests/should_succeed/type_invariants/vec_inv/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/unnest/why3session.xml b/creusot/tests/should_succeed/unnest/why3session.xml
index 136eb15df..103f7cd78 100644
--- a/creusot/tests/should_succeed/unnest/why3session.xml
+++ b/creusot/tests/should_succeed/unnest/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="unnest.mlcfg"/>
 <theory name="Unnest_Unnest" proved="true">
  <goal name="unnest&#39;vc" expl="VC for unnest" proved="true">
- <proof prover="1"><result status="valid" time="0.008807" steps="26"/></proof>
+ <proof prover="0"><result status="valid" time="0.008807" steps="26"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/unused_in_loop/why3session.xml b/creusot/tests/should_succeed/unused_in_loop/why3session.xml
index 3231342ce..8a832490b 100644
--- a/creusot/tests/should_succeed/unused_in_loop/why3session.xml
+++ b/creusot/tests/should_succeed/unused_in_loop/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="unused_in_loop.mlcfg"/>
 <theory name="UnusedInLoop_UnusedInLoop" proved="true">
  <goal name="unused_in_loop&#39;vc" expl="VC for unused_in_loop" proved="true">
- <proof prover="1"><result status="valid" time="0.007110" steps="10"/></proof>
+ <proof prover="0"><result status="valid" time="0.007110" steps="10"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/vecdeque/why3session.xml b/creusot/tests/should_succeed/vecdeque/why3session.xml
index 62b682d9f..b0bba52d8 100644
--- a/creusot/tests/should_succeed/vecdeque/why3session.xml
+++ b/creusot/tests/should_succeed/vecdeque/why3session.xml
@@ -2,111 +2,111 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="vecdeque.mlcfg"/>
 <theory name="Vecdeque_TestDeque" proved="true">
  <goal name="test_deque&#39;vc" expl="VC for test_deque" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="test_deque&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.006744" steps="11"/></proof>
+  <proof prover="3"><result status="valid" time="0.006744" steps="11"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.1" expl="VC for test_deque" proved="true">
-  <proof prover="2"><result status="valid" time="0.015298" steps="9"/></proof>
+  <proof prover="3"><result status="valid" time="0.015298" steps="8"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.018384" steps="12"/></proof>
+  <proof prover="3"><result status="valid" time="0.018384" steps="11"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.3" expl="VC for test_deque" proved="true">
-  <proof prover="2"><result status="valid" time="0.016911" steps="15"/></proof>
+  <proof prover="3"><result status="valid" time="0.016911" steps="14"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.016907" steps="24"/></proof>
+  <proof prover="3"><result status="valid" time="0.016907" steps="23"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.5" expl="VC for test_deque" proved="true">
-  <proof prover="2"><result status="valid" time="0.013994" steps="19"/></proof>
+  <proof prover="3"><result status="valid" time="0.013994" steps="19"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.010514" steps="25"/></proof>
+  <proof prover="3"><result status="valid" time="0.010514" steps="24"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.7" expl="VC for test_deque" proved="true">
-  <proof prover="2"><result status="valid" time="0.017351" steps="23"/></proof>
+  <proof prover="3"><result status="valid" time="0.017351" steps="22"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.016604" steps="33"/></proof>
+  <proof prover="3"><result status="valid" time="0.016604" steps="32"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.015340" steps="39"/></proof>
+  <proof prover="3"><result status="valid" time="0.015340" steps="38"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.014104" steps="40"/></proof>
+  <proof prover="3"><result status="valid" time="0.014104" steps="40"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.11" expl="VC for test_deque" proved="true">
-  <proof prover="2"><result status="valid" time="0.036262" steps="304"/></proof>
+  <proof prover="3"><result status="valid" time="0.036262" steps="303"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.12" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.017203" steps="45"/></proof>
+  <proof prover="3"><result status="valid" time="0.017203" steps="44"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.13" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.019733" steps="49"/></proof>
+  <proof prover="3"><result status="valid" time="0.019733" steps="48"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.016260" steps="50"/></proof>
+  <proof prover="3"><result status="valid" time="0.016260" steps="49"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.15" expl="VC for test_deque" proved="true">
-  <proof prover="2"><result status="valid" time="0.053939" steps="514"/></proof>
+  <proof prover="3"><result status="valid" time="0.053939" steps="513"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.019949" steps="57"/></proof>
+  <proof prover="3"><result status="valid" time="0.019949" steps="57"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.17" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.022440" steps="61"/></proof>
+  <proof prover="3"><result status="valid" time="0.022440" steps="61"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.18" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.020579" steps="78"/></proof>
+  <proof prover="3"><result status="valid" time="0.020579" steps="77"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.19" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.017564" steps="84"/></proof>
+  <proof prover="3"><result status="valid" time="0.017564" steps="83"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.20" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.029489" steps="99"/></proof>
+  <proof prover="3"><result status="valid" time="0.029489" steps="99"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.21" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.031548" steps="105"/></proof>
+  <proof prover="3"><result status="valid" time="0.031548" steps="105"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.22" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.038955" steps="113"/></proof>
+  <proof prover="3"><result status="valid" time="0.038955" steps="111"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.23" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.041070" steps="118"/></proof>
+  <proof prover="3"><result status="valid" time="0.041070" steps="117"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.24" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.036039" steps="119"/></proof>
+  <proof prover="3"><result status="valid" time="0.036039" steps="118"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.25" expl="VC for test_deque" proved="true">
-  <proof prover="0"><result status="valid" time="0.086368" steps="198713"/></proof>
+  <proof prover="1"><result status="valid" time="0.086368" steps="147198"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.26" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.026337" steps="123"/></proof>
+  <proof prover="3"><result status="valid" time="0.026337" steps="123"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.27" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.026044" steps="130"/></proof>
+  <proof prover="3"><result status="valid" time="0.026044" steps="130"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.28" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.030211" steps="131"/></proof>
+  <proof prover="3"><result status="valid" time="0.030211" steps="131"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.29" expl="VC for test_deque" proved="true">
-  <proof prover="2"><result status="valid" time="0.404906" steps="4269"/></proof>
+  <proof prover="3"><result status="valid" time="0.173450" steps="4266"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.30" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.031166" steps="137"/></proof>
+  <proof prover="3"><result status="valid" time="0.031166" steps="135"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.31" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.043553" steps="140"/></proof>
+  <proof prover="3"><result status="valid" time="0.043553" steps="140"/></proof>
   </goal>
   <goal name="test_deque&#39;vc.32" expl="VC for test_deque" proved="true">
-  <proof prover="2"><result status="valid" time="0.017023" steps="107"/></proof>
+  <proof prover="3"><result status="valid" time="0.017023" steps="107"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/vecdeque/why3shapes.gz b/creusot/tests/should_succeed/vecdeque/why3shapes.gz
index f0e291fc3..b3c323509 100644
Binary files a/creusot/tests/should_succeed/vecdeque/why3shapes.gz and b/creusot/tests/should_succeed/vecdeque/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/vector/01/why3session.xml b/creusot/tests/should_succeed/vector/01/why3session.xml
index 158c1776f..6848a3884 100644
--- a/creusot/tests/should_succeed/vector/01/why3session.xml
+++ b/creusot/tests/should_succeed/vector/01/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="01.mlcfg"/>
 <theory name="C01_AllZero" proved="true">
  <goal name="all_zero&#39;vc" expl="VC for all_zero" proved="true">
- <proof prover="1"><result status="valid" time="0.403443" steps="880151"/></proof>
+ <proof prover="0"><result status="valid" time="0.172182" steps="816789"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/vector/01/why3shapes.gz b/creusot/tests/should_succeed/vector/01/why3shapes.gz
index cf570080d..562528e1e 100644
Binary files a/creusot/tests/should_succeed/vector/01/why3shapes.gz and b/creusot/tests/should_succeed/vector/01/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/vector/02_gnome/why3session.xml b/creusot/tests/should_succeed/vector/02_gnome/why3session.xml
index 0f176444f..3c2be9c18 100644
--- a/creusot/tests/should_succeed/vector/02_gnome/why3session.xml
+++ b/creusot/tests/should_succeed/vector/02_gnome/why3session.xml
@@ -2,106 +2,106 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="02_gnome.mlcfg"/>
 <theory name="C02Gnome_GnomeSort" proved="true">
  <goal name="gnome_sort&#39;vc" expl="VC for gnome_sort" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="gnome_sort&#39;vc.0" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.016869" steps="8"/></proof>
+  <proof prover="3"><result status="valid" time="0.016869" steps="8"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.1" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.011344" steps="38"/></proof>
+  <proof prover="3"><result status="valid" time="0.011344" steps="38"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.2" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.020187" steps="102329"/></proof>
+  <proof prover="1"><result status="valid" time="0.020914" steps="93388"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.012033" steps="22"/></proof>
+  <proof prover="3"><result status="valid" time="0.012033" steps="22"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.4" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.012470" steps="71"/></proof>
+  <proof prover="3"><result status="valid" time="0.012470" steps="71"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.024421" steps="142276"/></proof>
+  <proof prover="1"><result status="valid" time="0.027521" steps="129258"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.010591" steps="39"/></proof>
+  <proof prover="3"><result status="valid" time="0.010591" steps="39"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.014700" steps="39"/></proof>
+  <proof prover="3"><result status="valid" time="0.014700" steps="39"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.8" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.010559" steps="34"/></proof>
+  <proof prover="3"><result status="valid" time="0.010559" steps="34"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.9" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.010845" steps="36"/></proof>
+  <proof prover="3"><result status="valid" time="0.010845" steps="36"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.025635" steps="148348"/></proof>
+  <proof prover="1"><result status="valid" time="0.028757" steps="136751"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.010375" steps="148433"/></proof>
+  <proof prover="1"><result status="valid" time="0.028250" steps="136826"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.12" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.024696" steps="42"/></proof>
+  <proof prover="3"><result status="valid" time="0.024696" steps="42"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.13" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.010624" steps="44"/></proof>
+  <proof prover="3"><result status="valid" time="0.010624" steps="44"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.015968" steps="46"/></proof>
+  <proof prover="3"><result status="valid" time="0.015968" steps="46"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.029629" steps="46"/></proof>
+  <proof prover="3"><result status="valid" time="0.029629" steps="46"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.16" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.025578" steps="133424"/></proof>
+  <proof prover="1"><result status="valid" time="0.026681" steps="120313"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.17" expl="postcondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.016845" steps="194"/></proof>
+  <proof prover="3"><result status="valid" time="0.016845" steps="193"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.18" expl="postcondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.023485" steps="136147"/></proof>
+  <proof prover="1"><result status="valid" time="0.027288" steps="124673"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.19" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.014145" steps="70"/></proof>
+  <proof prover="3"><result status="valid" time="0.014145" steps="70"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.20" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.014222" steps="82"/></proof>
+  <proof prover="3"><result status="valid" time="0.014222" steps="82"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.21" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.014839" steps="88"/></proof>
+  <proof prover="3"><result status="valid" time="0.014839" steps="88"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.22" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.014869" steps="93"/></proof>
+  <proof prover="3"><result status="valid" time="0.014869" steps="97"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.23" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.016746" steps="88"/></proof>
+  <proof prover="3"><result status="valid" time="0.016746" steps="88"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.24" expl="type invariant" proved="true">
-  <proof prover="2"><result status="valid" time="0.010592" steps="89"/></proof>
+  <proof prover="3"><result status="valid" time="0.010592" steps="89"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.25" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.014728" steps="94"/></proof>
+  <proof prover="3"><result status="valid" time="0.014728" steps="94"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.26" expl="integer overflow" proved="true">
-  <proof prover="0"><result status="valid" time="0.025082" steps="144691"/></proof>
+  <proof prover="1"><result status="valid" time="0.028493" steps="142012"/></proof>
   </goal>
   <goal name="gnome_sort&#39;vc.27" expl="loop invariant preservation" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="gnome_sort&#39;vc.27.0" expl="loop invariant preservation" proved="true">
-   <proof prover="2"><result status="valid" time="0.164719" steps="2852"/></proof>
+   <proof prover="3"><result status="valid" time="0.164719" steps="2844"/></proof>
    </goal>
    <goal name="gnome_sort&#39;vc.27.1" expl="loop invariant preservation" proved="true">
-   <proof prover="2"><result status="valid" time="0.234710" steps="5033"/></proof>
+   <proof prover="3"><result status="valid" time="0.234710" steps="5038"/></proof>
    </goal>
   </transf>
   </goal>
   <goal name="gnome_sort&#39;vc.28" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.024456" steps="260"/></proof>
+  <proof prover="3"><result status="valid" time="0.024456" steps="266"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/vector/02_gnome/why3shapes.gz b/creusot/tests/should_succeed/vector/02_gnome/why3shapes.gz
index e1d2ead2c..95bf9d8a1 100644
Binary files a/creusot/tests/should_succeed/vector/02_gnome/why3shapes.gz and b/creusot/tests/should_succeed/vector/02_gnome/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/vector/03_knuth_shuffle/why3session.xml b/creusot/tests/should_succeed/vector/03_knuth_shuffle/why3session.xml
index 5d71019b5..8c8daba04 100644
--- a/creusot/tests/should_succeed/vector/03_knuth_shuffle/why3session.xml
+++ b/creusot/tests/should_succeed/vector/03_knuth_shuffle/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="CVC4" version="1.8" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="03_knuth_shuffle.mlcfg"/>
 <theory name="C03KnuthShuffle_KnuthShuffle" proved="true">
  <goal name="knuth_shuffle&#39;vc" expl="VC for knuth_shuffle" proved="true">
- <proof prover="1"><result status="valid" time="0.368403" steps="89343"/></proof>
+ <proof prover="0"><result status="valid" time="0.340951" steps="102722"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/vector/03_knuth_shuffle/why3shapes.gz b/creusot/tests/should_succeed/vector/03_knuth_shuffle/why3shapes.gz
index 55927ee97..a56287781 100644
Binary files a/creusot/tests/should_succeed/vector/03_knuth_shuffle/why3shapes.gz and b/creusot/tests/should_succeed/vector/03_knuth_shuffle/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/vector/04_binary_search/why3session.xml b/creusot/tests/should_succeed/vector/04_binary_search/why3session.xml
index 85a37fc43..2dfab7153 100644
--- a/creusot/tests/should_succeed/vector/04_binary_search/why3session.xml
+++ b/creusot/tests/should_succeed/vector/04_binary_search/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="04_binary_search.mlcfg"/>
 <theory name="C04BinarySearch_BinarySearch" proved="true">
  <goal name="binary_search&#39;vc" expl="VC for binary_search" proved="true">
- <proof prover="1"><result status="valid" time="0.043744" steps="188060"/></proof>
+ <proof prover="0"><result status="valid" time="0.043744" steps="223994"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/vector/04_binary_search/why3shapes.gz b/creusot/tests/should_succeed/vector/04_binary_search/why3shapes.gz
index 96bfe0f2e..5d7bf11dd 100644
Binary files a/creusot/tests/should_succeed/vector/04_binary_search/why3shapes.gz and b/creusot/tests/should_succeed/vector/04_binary_search/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/vector/05_binary_search_generic/why3session.xml b/creusot/tests/should_succeed/vector/05_binary_search_generic/why3session.xml
index df588d00c..9f01f219a 100644
--- a/creusot/tests/should_succeed/vector/05_binary_search_generic/why3session.xml
+++ b/creusot/tests/should_succeed/vector/05_binary_search_generic/why3session.xml
@@ -2,118 +2,118 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="2" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="4" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="05_binary_search_generic.mlcfg"/>
 <theory name="C05BinarySearchGeneric_BinarySearch" proved="true">
  <goal name="binary_search&#39;vc" expl="VC for binary_search" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="binary_search&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.012406" steps="10"/></proof>
+  <proof prover="4"><result status="valid" time="0.012406" steps="10"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.1" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.007496" steps="18"/></proof>
+  <proof prover="4"><result status="valid" time="0.007496" steps="17"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.2" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.020246" steps="18"/></proof>
+  <proof prover="4"><result status="valid" time="0.020246" steps="18"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.008765" steps="18"/></proof>
+  <proof prover="4"><result status="valid" time="0.008765" steps="18"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.017749" steps="72738"/></proof>
+  <proof prover="2"><result status="valid" time="0.017749" steps="73423"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.5" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.020032" steps="89396"/></proof>
+  <proof prover="2"><result status="valid" time="0.020032" steps="87928"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.6" expl="loop invariant init" proved="true">
-  <proof prover="1"><result status="valid" time="0.008712" steps="28"/></proof>
+  <proof prover="4"><result status="valid" time="0.008712" steps="27"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.7" expl="division by zero" proved="true">
-  <proof prover="1"><result status="valid" time="0.008926" steps="31"/></proof>
+  <proof prover="4"><result status="valid" time="0.008926" steps="31"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.8" expl="division by zero" proved="true">
-  <proof prover="1"><result status="valid" time="0.008616" steps="35"/></proof>
+  <proof prover="4"><result status="valid" time="0.008616" steps="35"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.9" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.011959" steps="91"/></proof>
+  <proof prover="4"><result status="valid" time="0.011959" steps="90"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.10" expl="integer overflow" proved="true">
-  <proof prover="0"><result status="valid" time="0.021739" steps="102707"/></proof>
+  <proof prover="2"><result status="valid" time="0.021739" steps="101087"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.021647" steps="102086"/></proof>
+  <proof prover="2"><result status="valid" time="0.021647" steps="100466"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.12" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.013170" steps="41"/></proof>
+  <proof prover="4"><result status="valid" time="0.013170" steps="41"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.13" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.019786" steps="100401"/></proof>
+  <proof prover="2"><result status="valid" time="0.019786" steps="98933"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.14" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.008558" steps="43"/></proof>
+  <proof prover="4"><result status="valid" time="0.008558" steps="43"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.009508" steps="45"/></proof>
+  <proof prover="4"><result status="valid" time="0.009508" steps="45"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.010248" steps="105"/></proof>
+  <proof prover="4"><result status="valid" time="0.010248" steps="105"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.17" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.022533" steps="28"/></proof>
+  <proof prover="4"><result status="valid" time="0.022533" steps="28"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.18" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.008769" steps="30"/></proof>
+  <proof prover="4"><result status="valid" time="0.008769" steps="30"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.19" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.069202" steps="11993"/></proof>
+  <proof prover="3"><result status="valid" time="0.069202" steps="10846"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.20" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.008900" steps="43"/></proof>
+  <proof prover="4"><result status="valid" time="0.008900" steps="43"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.21" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.010241" steps="36"/></proof>
+  <proof prover="4"><result status="valid" time="0.010241" steps="36"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.22" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.008788" steps="38"/></proof>
+  <proof prover="4"><result status="valid" time="0.008788" steps="38"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.23" expl="type invariant" proved="true">
-  <proof prover="1"><result status="valid" time="0.008573" steps="50"/></proof>
+  <proof prover="4"><result status="valid" time="0.008573" steps="50"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.24" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.011303" steps="46"/></proof>
+  <proof prover="4"><result status="valid" time="0.011303" steps="46"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.25" expl="precondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.028871" steps="46"/></proof>
+  <proof prover="4"><result status="valid" time="0.028871" steps="46"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.26" expl="type invariant" proved="true">
-  <proof prover="0"><result status="valid" time="0.009512" steps="7266"/></proof>
+  <proof prover="2"><result status="valid" time="0.009512" steps="7477"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.27" expl="integer overflow" proved="true">
-  <proof prover="0"><result status="valid" time="0.020319" steps="94377"/></proof>
+  <proof prover="2"><result status="valid" time="0.020319" steps="94785"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.28" expl="integer overflow" proved="true">
-  <proof prover="1"><result status="valid" time="0.026441" steps="454"/></proof>
+  <proof prover="4"><result status="valid" time="0.026441" steps="454"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.29" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.018221" steps="221"/></proof>
+  <proof prover="4"><result status="valid" time="0.018221" steps="221"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.30" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="0.352712" steps="53397"/></proof>
+  <proof prover="3"><result status="valid" time="0.123755" steps="45711"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.31" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="0.347815" steps="37160"/></proof>
+  <proof prover="3"><result status="valid" time="0.119156" steps="36161"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.32" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.028855" steps="412"/></proof>
+  <proof prover="4"><result status="valid" time="0.028855" steps="410"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.33" expl="postcondition" proved="true">
-  <proof prover="1"><result status="valid" time="0.231345" steps="1427"/></proof>
+  <proof prover="4"><result status="valid" time="0.076317" steps="1426"/></proof>
   </goal>
   <goal name="binary_search&#39;vc.34" expl="postcondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.032788" steps="130861"/></proof>
+  <proof prover="2"><result status="valid" time="0.032788" steps="123363"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/vector/05_binary_search_generic/why3shapes.gz b/creusot/tests/should_succeed/vector/05_binary_search_generic/why3shapes.gz
index e09a15023..ca4cd7cbd 100644
Binary files a/creusot/tests/should_succeed/vector/05_binary_search_generic/why3shapes.gz and b/creusot/tests/should_succeed/vector/05_binary_search_generic/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/vector/06_knights_tour/why3session.xml b/creusot/tests/should_succeed/vector/06_knights_tour/why3session.xml
index 4a1abc4bf..c3527f26a 100644
--- a/creusot/tests/should_succeed/vector/06_knights_tour/why3session.xml
+++ b/creusot/tests/should_succeed/vector/06_knights_tour/why3session.xml
@@ -2,87 +2,87 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
+<prover id="0" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="1" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Z3" version="4.12.1" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="4" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="3" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="06_knights_tour.mlcfg"/>
 <theory name="C06KnightsTour_Impl3_Clone" proved="true">
  <goal name="clone&#39;&#39;vc" expl="VC for clone&#39;" proved="true">
- <proof prover="4"><result status="valid" time="0.000000" steps="12"/></proof>
+ <proof prover="3"><result status="valid" time="0.000000" steps="12"/></proof>
  </goal>
 </theory>
 <theory name="C06KnightsTour_Impl0_Mov" proved="true">
  <goal name="mov&#39;vc" expl="VC for mov" proved="true">
- <proof prover="4"><result status="valid" time="0.020000" steps="311"/></proof>
+ <proof prover="3"><result status="valid" time="0.020000" steps="310"/></proof>
  </goal>
 </theory>
 <theory name="C06KnightsTour_Impl1_New_Closure3" proved="true">
  <goal name="c06KnightsTour_Impl1_New_Closure3&#39;vc" expl="VC for c06KnightsTour_Impl1_New_Closure3" proved="true">
- <proof prover="4"><result status="valid" time="0.000000" steps="33"/></proof>
+ <proof prover="3"><result status="valid" time="0.000000" steps="32"/></proof>
  </goal>
 </theory>
 <theory name="C06KnightsTour_Impl1_New" proved="true">
  <goal name="new&#39;vc" expl="VC for new" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="new&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.041075" steps="23"/></proof>
+  <proof prover="3"><result status="valid" time="0.041075" steps="23"/></proof>
   </goal>
   <goal name="new&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.079378" steps="170"/></proof>
+  <proof prover="3"><result status="valid" time="0.079378" steps="170"/></proof>
   </goal>
   <goal name="new&#39;vc.2" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.048165" steps="59"/></proof>
+  <proof prover="3"><result status="valid" time="0.048165" steps="59"/></proof>
   </goal>
   <goal name="new&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.029300" steps="16"/></proof>
+  <proof prover="3"><result status="valid" time="0.029300" steps="16"/></proof>
   </goal>
   <goal name="new&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.032098" steps="18"/></proof>
+  <proof prover="3"><result status="valid" time="0.032098" steps="18"/></proof>
   </goal>
   <goal name="new&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.026648" steps="15"/></proof>
+  <proof prover="3"><result status="valid" time="0.026648" steps="15"/></proof>
   </goal>
   <goal name="new&#39;vc.6" expl="postcondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.041395" steps="64"/></proof>
+  <proof prover="3"><result status="valid" time="0.041395" steps="64"/></proof>
   </goal>
   <goal name="new&#39;vc.7" expl="postcondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.066909" steps="346267"/></proof>
+  <proof prover="0"><result status="valid" time="0.066909" steps="461805"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="C06KnightsTour_Impl1_Available" proved="true">
  <goal name="available&#39;vc" expl="VC for available" proved="true">
- <proof prover="4"><result status="valid" time="0.030000" steps="534"/></proof>
+ <proof prover="3"><result status="valid" time="0.030000" steps="533"/></proof>
  </goal>
 </theory>
 <theory name="C06KnightsTour_Impl1_CountDegree" proved="true">
  <goal name="count_degree&#39;vc" expl="VC for count_degree" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="count_degree&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.000000" steps="12"/></proof>
+  <proof prover="3"><result status="valid" time="0.000000" steps="12"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.021056" steps="19"/></proof>
+  <proof prover="3"><result status="valid" time="0.021056" steps="17"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.2" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.000000" steps="20"/></proof>
+  <proof prover="3"><result status="valid" time="0.000000" steps="20"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.3" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="26"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="26"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.4" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="31"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="31"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.020679" steps="36"/></proof>
+  <proof prover="3"><result status="valid" time="0.020679" steps="36"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="109"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="109"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.020000" steps="117"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="117"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.8" expl="precondition" proved="true">
   <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
@@ -95,7 +95,7 @@
       <goal name="count_degree&#39;vc.8.0.0.0.0" expl="VC for count_degree" proved="true">
       <transf name="inline_goal" proved="true" >
        <goal name="count_degree&#39;vc.8.0.0.0.0.0" expl="VC for count_degree" proved="true">
-       <proof prover="4" timelimit="30" memlimit="4000"><result status="valid" time="3.264339" steps="16873"/></proof>
+       <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="0.753991" steps="16876"/></proof>
        </goal>
       </transf>
       </goal>
@@ -110,7 +110,7 @@
       <goal name="count_degree&#39;vc.8.0.1.0.0" expl="VC for count_degree" proved="true">
       <transf name="inline_goal" proved="true" >
        <goal name="count_degree&#39;vc.8.0.1.0.0.0" expl="VC for count_degree" proved="true">
-       <proof prover="4" timelimit="30" memlimit="4000"><result status="valid" time="3.385215" steps="16891"/></proof>
+       <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="0.758364" steps="16919"/></proof>
        </goal>
       </transf>
       </goal>
@@ -133,7 +133,7 @@
       <goal name="count_degree&#39;vc.9.0.0.0.0" expl="VC for count_degree" proved="true">
       <transf name="inline_goal" proved="true" >
        <goal name="count_degree&#39;vc.9.0.0.0.0.0" expl="VC for count_degree" proved="true">
-       <proof prover="4" timelimit="30" memlimit="4000"><result status="valid" time="3.533824" steps="17178"/></proof>
+       <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="0.767532" steps="17168"/></proof>
        </goal>
       </transf>
       </goal>
@@ -148,7 +148,7 @@
       <goal name="count_degree&#39;vc.9.0.1.0.0" expl="VC for count_degree" proved="true">
       <transf name="inline_goal" proved="true" >
        <goal name="count_degree&#39;vc.9.0.1.0.0.0" expl="VC for count_degree" proved="true">
-       <proof prover="4" timelimit="30" memlimit="4000"><result status="valid" time="3.431793" steps="17195"/></proof>
+       <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="0.775345" steps="17231"/></proof>
        </goal>
       </transf>
       </goal>
@@ -161,25 +161,25 @@
   </transf>
   </goal>
   <goal name="count_degree&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.020000" steps="65"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="65"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.11" expl="integer overflow" proved="true">
-  <proof prover="4"><result status="valid" time="0.223396" steps="847"/></proof>
+  <proof prover="3"><result status="valid" time="0.052571" steps="846"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.12" expl="loop invariant preservation" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="42"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="42"/></proof>
   </goal>
   <goal name="count_degree&#39;vc.13" expl="loop invariant preservation" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="count_degree&#39;vc.13.0" expl="loop invariant preservation" proved="true">
-   <proof prover="4"><result status="valid" time="0.326915" steps="996"/></proof>
+   <proof prover="3"><result status="valid" time="0.062400" steps="995"/></proof>
    </goal>
   </transf>
   </goal>
   <goal name="count_degree&#39;vc.14" expl="loop invariant preservation" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="count_degree&#39;vc.14.0" expl="loop invariant preservation" proved="true">
-   <proof prover="4"><result status="valid" time="0.010000" steps="222"/></proof>
+   <proof prover="3"><result status="valid" time="0.010000" steps="222"/></proof>
    </goal>
   </transf>
   </goal>
@@ -188,7 +188,7 @@
 </theory>
 <theory name="C06KnightsTour_Impl1_Set" proved="true">
  <goal name="set&#39;vc" expl="VC for set" proved="true">
- <proof prover="4"><result status="valid" time="1.635298" steps="5729"/></proof>
+ <proof prover="3"><result status="valid" time="0.362387" steps="5728"/></proof>
  </goal>
 </theory>
 <theory name="C06KnightsTour_Min" proved="true">
@@ -197,28 +197,28 @@
   <goal name="min&#39;vc.0" expl="VC for min" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="min&#39;vc.0.0" expl="precondition" proved="true">
-   <proof prover="4"><result status="valid" time="0.000000" steps="4"/></proof>
+   <proof prover="3"><result status="valid" time="0.000000" steps="4"/></proof>
    </goal>
    <goal name="min&#39;vc.0.1" expl="precondition" proved="true">
-   <proof prover="4"><result status="valid" time="0.009531" steps="8"/></proof>
+   <proof prover="3"><result status="valid" time="0.009531" steps="6"/></proof>
    </goal>
    <goal name="min&#39;vc.0.2" expl="loop invariant init" proved="true">
-   <proof prover="4"><result status="valid" time="0.000000" steps="12"/></proof>
+   <proof prover="3"><result status="valid" time="0.000000" steps="12"/></proof>
    </goal>
    <goal name="min&#39;vc.0.3" expl="loop invariant init" proved="true">
-   <proof prover="2"><result status="valid" time="0.020000" steps="61654"/></proof>
+   <proof prover="0"><result status="valid" time="0.020000" steps="62510"/></proof>
    </goal>
    <goal name="min&#39;vc.0.4" expl="loop invariant init" proved="true">
-   <proof prover="4"><result status="valid" time="0.000000" steps="20"/></proof>
+   <proof prover="3"><result status="valid" time="0.000000" steps="19"/></proof>
    </goal>
    <goal name="min&#39;vc.0.5" expl="postcondition" proved="true">
-   <proof prover="4"><result status="valid" time="0.010000" steps="82"/></proof>
+   <proof prover="3"><result status="valid" time="0.010000" steps="81"/></proof>
    </goal>
    <goal name="min&#39;vc.0.6" expl="loop invariant preservation" proved="true">
-   <proof prover="4"><result status="valid" time="0.010000" steps="17"/></proof>
+   <proof prover="3"><result status="valid" time="0.010000" steps="17"/></proof>
    </goal>
    <goal name="min&#39;vc.0.7" expl="loop invariant preservation" proved="true">
-   <proof prover="1"><result status="valid" time="0.222478" steps="25965"/></proof>
+   <proof prover="1"><result status="valid" time="0.076049" steps="25791"/></proof>
    </goal>
    <goal name="min&#39;vc.0.8" expl="loop invariant preservation" proved="true">
    <transf name="split_vc" proved="true" >
@@ -229,7 +229,7 @@
       <goal name="min&#39;vc.0.8.0.0.0" expl="loop invariant preservation" proved="true">
       <transf name="split_vc" proved="true" >
        <goal name="min&#39;vc.0.8.0.0.0.0" expl="loop invariant preservation" proved="true">
-       <proof prover="4"><result status="valid" time="1.032809" steps="13235"/></proof>
+       <proof prover="3"><result status="valid" time="0.535349" steps="13230"/></proof>
        </goal>
       </transf>
       </goal>
@@ -248,14 +248,14 @@
         <goal name="min&#39;vc.0.8.1.0.0.0.0" expl="loop invariant preservation" proved="true">
         <transf name="split_all_full" proved="true" >
          <goal name="min&#39;vc.0.8.1.0.0.0.0.0" expl="loop invariant preservation" proved="true">
-         <proof prover="4" timelimit="30" memlimit="4000"><result status="valid" time="2.601782" steps="22976"/></proof>
+         <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="1.154758" steps="22905"/></proof>
          </goal>
         </transf>
         </goal>
        </transf>
        </goal>
        <goal name="min&#39;vc.0.8.1.0.0.1" expl="loop invariant preservation" proved="true">
-       <proof prover="4"><result status="valid" time="0.044256" steps="237"/></proof>
+       <proof prover="3"><result status="valid" time="0.044256" steps="236"/></proof>
        </goal>
       </transf>
       </goal>
@@ -272,103 +272,103 @@
 </theory>
 <theory name="C06KnightsTour_DumbNonlinearArith_Impl" proved="true">
  <goal name="dumb_nonlinear_arith&#39;vc" expl="VC for dumb_nonlinear_arith" proved="true">
- <proof prover="4"><result status="valid" time="0.000000" steps="7"/></proof>
+ <proof prover="3"><result status="valid" time="0.000000" steps="7"/></proof>
  </goal>
 </theory>
 <theory name="C06KnightsTour_KnightsTour" proved="true">
  <goal name="knights_tour&#39;vc" expl="VC for knights_tour" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="knights_tour&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.000000" steps="10"/></proof>
+  <proof prover="3"><result status="valid" time="0.000000" steps="10"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.1" expl="integer overflow" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="32"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="31"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.2" expl="integer overflow" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="37"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="36"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="30"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="30"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.191980" steps="595"/></proof>
+  <proof prover="3"><result status="valid" time="0.037506" steps="594"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="35"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="34"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.6" expl="integer overflow" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="63"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="63"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.7" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="43"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="42"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.8" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.038473" steps="177"/></proof>
+  <proof prover="3"><result status="valid" time="0.038473" steps="177"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.9" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="73"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="71"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.10" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.122769" steps="251"/></proof>
+  <proof prover="3"><result status="valid" time="0.122769" steps="249"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.11" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="79"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="78"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.12" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="83"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="82"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.13" expl="loop invariant init" proved="true">
-  <proof prover="4" timelimit="5"><result status="valid" time="0.549388" steps="3499"/></proof>
+  <proof prover="3" timelimit="5"><result status="valid" time="0.128006" steps="3497"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.050239" steps="300"/></proof>
+  <proof prover="3"><result status="valid" time="0.050239" steps="299"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.15" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="199"/></proof>
+  <proof prover="3"><result status="valid" time="0.030000" steps="199"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.16" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.086621" steps="415"/></proof>
+  <proof prover="3"><result status="valid" time="0.086621" steps="414"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.17" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.030000" steps="220"/></proof>
+  <proof prover="3"><result status="valid" time="0.030000" steps="219"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.18" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.037720" steps="540"/></proof>
+  <proof prover="3"><result status="valid" time="0.037720" steps="540"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.19" expl="loop invariant init" proved="true">
-  <proof prover="4"><result status="valid" time="0.040000" steps="227"/></proof>
+  <proof prover="3"><result status="valid" time="0.040000" steps="226"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.20" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.079357" steps="495"/></proof>
+  <proof prover="3"><result status="valid" time="0.079357" steps="495"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.21" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.100000" steps="311"/></proof>
+  <proof prover="3"><result status="valid" time="0.100000" steps="310"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.22" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.201008" steps="1952"/></proof>
+  <proof prover="3"><result status="valid" time="0.077592" steps="1951"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.23" expl="loop invariant preservation" proved="true">
-  <proof prover="4" timelimit="5"><result status="valid" time="0.058954" steps="613"/></proof>
+  <proof prover="3" timelimit="5"><result status="valid" time="0.058954" steps="612"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.24" expl="loop invariant preservation" proved="true">
-  <proof prover="4"><result status="valid" time="0.915583" steps="7973"/></proof>
+  <proof prover="3"><result status="valid" time="0.304490" steps="7974"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.25" expl="loop invariant preservation" proved="true">
-  <proof prover="4"><result status="valid" time="0.020000" steps="335"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="335"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.26" expl="loop invariant preservation" proved="true">
-  <proof prover="1" timelimit="5" memlimit="2000"><result status="valid" time="0.130000" steps="21821"/></proof>
+  <proof prover="1" timelimit="5" memlimit="2000"><result status="valid" time="0.130000" steps="21125"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.27" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="0.328578" steps="39713"/></proof>
+  <proof prover="1"><result status="valid" time="0.135677" steps="39265"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.28" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.040000" steps="932"/></proof>
+  <proof prover="3"><result status="valid" time="0.040000" steps="932"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.29" expl="precondition" proved="true">
   <transf name="use_th" proved="true" arg1="seq.FreeMonoid">
    <goal name="knights_tour&#39;vc.29.0" expl="precondition" proved="true">
-   <proof prover="4"><result status="valid" time="0.050000" steps="1050"/></proof>
+   <proof prover="3"><result status="valid" time="0.050000" steps="1050"/></proof>
    </goal>
   </transf>
   </goal>
@@ -383,7 +383,7 @@
       <goal name="knights_tour&#39;vc.30.0.0.0.0" expl="VC for knights_tour" proved="true">
       <transf name="inline_goal" proved="true" >
        <goal name="knights_tour&#39;vc.30.0.0.0.0.0" expl="VC for knights_tour" proved="true">
-       <proof prover="4" timelimit="30" memlimit="4000"><result status="valid" time="7.659475" steps="52434"/></proof>
+       <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="2.209465" steps="52447"/></proof>
        </goal>
       </transf>
       </goal>
@@ -398,7 +398,7 @@
       <goal name="knights_tour&#39;vc.30.0.1.0.0" expl="VC for knights_tour" proved="true">
       <transf name="inline_goal" proved="true" >
        <goal name="knights_tour&#39;vc.30.0.1.0.0.0" expl="VC for knights_tour" proved="true">
-       <proof prover="4" timelimit="30" memlimit="4000"><result status="valid" time="7.074190" steps="52495"/></proof>
+       <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="2.214089" steps="52507"/></proof>
        </goal>
       </transf>
       </goal>
@@ -421,7 +421,7 @@
       <goal name="knights_tour&#39;vc.31.0.0.0.0" expl="VC for knights_tour" proved="true">
       <transf name="inline_goal" proved="true" >
        <goal name="knights_tour&#39;vc.31.0.0.0.0.0" expl="VC for knights_tour" proved="true">
-       <proof prover="4" timelimit="30" memlimit="4000"><result status="valid" time="7.771057" steps="52990"/></proof>
+       <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="2.256303" steps="52990"/></proof>
        </goal>
       </transf>
       </goal>
@@ -436,7 +436,7 @@
       <goal name="knights_tour&#39;vc.31.0.1.0.0" expl="VC for knights_tour" proved="true">
       <transf name="inline_goal" proved="true" >
        <goal name="knights_tour&#39;vc.31.0.1.0.0.0" expl="VC for knights_tour" proved="true">
-       <proof prover="4" timelimit="30" memlimit="4000"><result status="valid" time="8.171911" steps="53051"/></proof>
+       <proof prover="3" timelimit="30" memlimit="4000"><result status="valid" time="2.256854" steps="53056"/></proof>
        </goal>
       </transf>
       </goal>
@@ -449,43 +449,43 @@
   </transf>
   </goal>
   <goal name="knights_tour&#39;vc.32" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.020000" steps="359"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="359"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.33" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.020000" steps="373"/></proof>
+  <proof prover="3"><result status="valid" time="0.020000" steps="371"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.34" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.010000" steps="373"/></proof>
+  <proof prover="3"><result status="valid" time="0.010000" steps="371"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.35" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.156337" steps="852"/></proof>
+  <proof prover="3"><result status="valid" time="0.029820" steps="851"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.36" expl="precondition" proved="true">
-  <proof prover="4"><result status="valid" time="0.118800" steps="862"/></proof>
+  <proof prover="3"><result status="valid" time="0.118800" steps="862"/></proof>
   </goal>
   <goal name="knights_tour&#39;vc.37" expl="loop invariant preservation" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="knights_tour&#39;vc.37.0" expl="loop invariant preservation" proved="true">
-   <proof prover="4"><result status="valid" time="0.169823" steps="894"/></proof>
+   <proof prover="3"><result status="valid" time="0.030719" steps="894"/></proof>
    </goal>
   </transf>
   </goal>
   <goal name="knights_tour&#39;vc.38" expl="loop invariant preservation" proved="true">
   <transf name="split_vc" proved="true" >
    <goal name="knights_tour&#39;vc.38.0" expl="loop invariant preservation" proved="true">
-   <proof prover="4"><result status="valid" time="1.209185" steps="8241"/></proof>
+   <proof prover="3"><result status="valid" time="0.394194" steps="8246"/></proof>
    </goal>
   </transf>
   </goal>
   <goal name="knights_tour&#39;vc.39" expl="loop invariant preservation" proved="true">
-  <proof prover="1"><result status="valid" time="1.010977" steps="78121"/></proof>
+  <proof prover="1"><result status="valid" time="0.305249" steps="77028"/></proof>
   </goal>
  </transf>
  </goal>
 </theory>
 <theory name="C06KnightsTour_Impl3" proved="true">
  <goal name="clone&#39;_refn" proved="true">
- <proof prover="4"><result status="valid" time="0.000000" steps="6"/></proof>
+ <proof prover="3"><result status="valid" time="0.000000" steps="6"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/vector/06_knights_tour/why3shapes.gz b/creusot/tests/should_succeed/vector/06_knights_tour/why3shapes.gz
index 3a6bd76c9..574aed745 100644
Binary files a/creusot/tests/should_succeed/vector/06_knights_tour/why3shapes.gz and b/creusot/tests/should_succeed/vector/06_knights_tour/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/vector/07_read_write/why3session.xml b/creusot/tests/should_succeed/vector/07_read_write/why3session.xml
index 68f3e78f7..4d6b40519 100644
--- a/creusot/tests/should_succeed/vector/07_read_write/why3session.xml
+++ b/creusot/tests/should_succeed/vector/07_read_write/why3session.xml
@@ -2,12 +2,12 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="07_read_write.mlcfg"/>
 <theory name="C07ReadWrite_ReadWrite" proved="true">
  <goal name="read_write&#39;vc" expl="VC for read_write" proved="true">
- <proof prover="1"><result status="valid" time="0.021785" steps="174"/></proof>
+ <proof prover="0"><result status="valid" time="0.021785" steps="173"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/vector/07_read_write/why3shapes.gz b/creusot/tests/should_succeed/vector/07_read_write/why3shapes.gz
index a9a5b1dee..7eaf167fb 100644
Binary files a/creusot/tests/should_succeed/vector/07_read_write/why3shapes.gz and b/creusot/tests/should_succeed/vector/07_read_write/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/vector/08_haystack/why3session.xml b/creusot/tests/should_succeed/vector/08_haystack/why3session.xml
index 90a474bd5..9ebd25945 100644
--- a/creusot/tests/should_succeed/vector/08_haystack/why3session.xml
+++ b/creusot/tests/should_succeed/vector/08_haystack/why3session.xml
@@ -2,118 +2,118 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="0" name="Z3" version="4.11.2" timelimit="1" steplimit="0" memlimit="1000"/>
-<prover id="2" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="1" name="Z3" version="4.12.2" timelimit="1" steplimit="0" memlimit="1000"/>
 <prover id="3" name="CVC5" version="1.0.5" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="4" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="08_haystack.mlcfg"/>
 <theory name="C08Haystack_Search" proved="true">
  <goal name="search&#39;vc" expl="VC for search" proved="true">
  <transf name="split_vc" proved="true" >
   <goal name="search&#39;vc.0" expl="precondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.155020" steps="11262"/></proof>
+  <proof prover="3"><result status="valid" time="0.027003" steps="10664"/></proof>
   </goal>
   <goal name="search&#39;vc.1" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.028733" steps="84507"/></proof>
+  <proof prover="1"><result status="valid" time="0.021521" steps="78454"/></proof>
   </goal>
   <goal name="search&#39;vc.2" expl="integer overflow" proved="true">
-  <proof prover="2"><result status="valid" time="0.009606" steps="23"/></proof>
+  <proof prover="4"><result status="valid" time="0.009606" steps="23"/></proof>
   </goal>
   <goal name="search&#39;vc.3" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.016841" steps="29"/></proof>
+  <proof prover="4"><result status="valid" time="0.016841" steps="29"/></proof>
   </goal>
   <goal name="search&#39;vc.4" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.019284" steps="85188"/></proof>
+  <proof prover="1"><result status="valid" time="0.021902" steps="79091"/></proof>
   </goal>
   <goal name="search&#39;vc.5" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.008654" steps="18"/></proof>
+  <proof prover="4"><result status="valid" time="0.008654" steps="18"/></proof>
   </goal>
   <goal name="search&#39;vc.6" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.035544" steps="6802"/></proof>
+  <proof prover="1"><result status="valid" time="0.011722" steps="6990"/></proof>
   </goal>
   <goal name="search&#39;vc.7" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.010443" steps="25"/></proof>
+  <proof prover="4"><result status="valid" time="0.010443" steps="25"/></proof>
   </goal>
   <goal name="search&#39;vc.8" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.010430" steps="47"/></proof>
+  <proof prover="4"><result status="valid" time="0.010430" steps="47"/></proof>
   </goal>
   <goal name="search&#39;vc.9" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.023052" steps="124542"/></proof>
+  <proof prover="1"><result status="valid" time="0.025817" steps="111815"/></proof>
   </goal>
   <goal name="search&#39;vc.10" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.030444" steps="52"/></proof>
+  <proof prover="4"><result status="valid" time="0.030444" steps="52"/></proof>
   </goal>
   <goal name="search&#39;vc.11" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.008926" steps="56"/></proof>
+  <proof prover="4"><result status="valid" time="0.008926" steps="56"/></proof>
   </goal>
   <goal name="search&#39;vc.12" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.019476" steps="130704"/></proof>
+  <proof prover="1"><result status="valid" time="0.027197" steps="119004"/></proof>
   </goal>
   <goal name="search&#39;vc.13" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.009955" steps="9225"/></proof>
+  <proof prover="1"><result status="valid" time="0.012903" steps="9560"/></proof>
   </goal>
   <goal name="search&#39;vc.14" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.086810" steps="79"/></proof>
+  <proof prover="4"><result status="valid" time="0.086810" steps="79"/></proof>
   </goal>
   <goal name="search&#39;vc.15" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.008849" steps="65"/></proof>
+  <proof prover="4"><result status="valid" time="0.008849" steps="65"/></proof>
   </goal>
   <goal name="search&#39;vc.16" expl="loop invariant init" proved="true">
-  <proof prover="2"><result status="valid" time="0.013109" steps="94"/></proof>
+  <proof prover="4"><result status="valid" time="0.013109" steps="94"/></proof>
   </goal>
   <goal name="search&#39;vc.17" expl="loop invariant init" proved="true">
-  <proof prover="0"><result status="valid" time="0.075230" steps="412578"/></proof>
+  <proof prover="1"><result status="valid" time="0.110319" steps="511866"/></proof>
   </goal>
   <goal name="search&#39;vc.18" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.024488" steps="134017"/></proof>
+  <proof prover="1"><result status="valid" time="0.027203" steps="122080"/></proof>
   </goal>
   <goal name="search&#39;vc.19" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.055409" steps="967"/></proof>
+  <proof prover="4"><result status="valid" time="0.055409" steps="962"/></proof>
   </goal>
   <goal name="search&#39;vc.20" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.020785" steps="131"/></proof>
+  <proof prover="4"><result status="valid" time="0.020785" steps="131"/></proof>
   </goal>
   <goal name="search&#39;vc.21" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.018639" steps="131"/></proof>
+  <proof prover="4"><result status="valid" time="0.018639" steps="131"/></proof>
   </goal>
   <goal name="search&#39;vc.22" expl="integer overflow" proved="true">
-  <proof prover="0"><result status="valid" time="0.027655" steps="152896"/></proof>
+  <proof prover="1"><result status="valid" time="0.034007" steps="159511"/></proof>
   </goal>
   <goal name="search&#39;vc.23" expl="precondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.114528" steps="620054"/></proof>
+  <proof prover="1"><result status="valid" time="0.287861" steps="1270843"/></proof>
   </goal>
   <goal name="search&#39;vc.24" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009833" steps="142"/></proof>
+  <proof prover="4"><result status="valid" time="0.009833" steps="142"/></proof>
   </goal>
   <goal name="search&#39;vc.25" expl="precondition" proved="true">
-  <proof prover="2"><result status="valid" time="0.009715" steps="143"/></proof>
+  <proof prover="4"><result status="valid" time="0.009715" steps="143"/></proof>
   </goal>
   <goal name="search&#39;vc.26" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="0.191848" steps="18051"/></proof>
+  <proof prover="3"><result status="valid" time="0.049810" steps="17572"/></proof>
   </goal>
   <goal name="search&#39;vc.27" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.119033" steps="624778"/></proof>
+  <proof prover="1"><result status="valid" time="0.297581" steps="1244685"/></proof>
   </goal>
   <goal name="search&#39;vc.28" expl="loop invariant preservation" proved="true">
-  <proof prover="3"><result status="valid" time="0.326537" steps="50293"/></proof>
+  <proof prover="3"><result status="valid" time="0.189997" steps="49183"/></proof>
   </goal>
   <goal name="search&#39;vc.29" expl="loop invariant preservation" proved="true">
-  <proof prover="0"><result status="valid" time="0.029358" steps="146430"/></proof>
+  <proof prover="1"><result status="valid" time="0.028925" steps="135647"/></proof>
   </goal>
   <goal name="search&#39;vc.30" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.151645" steps="2638"/></proof>
+  <proof prover="4"><result status="valid" time="0.151645" steps="2655"/></proof>
   </goal>
   <goal name="search&#39;vc.31" expl="loop invariant preservation" proved="true">
-  <proof prover="2"><result status="valid" time="0.329596" steps="7202"/></proof>
+  <proof prover="4"><result status="valid" time="0.329596" steps="7287"/></proof>
   </goal>
   <goal name="search&#39;vc.32" expl="postcondition" proved="true">
-  <proof prover="3"><result status="valid" time="0.139861" steps="22306"/></proof>
+  <proof prover="3"><result status="valid" time="0.139861" steps="21499"/></proof>
   </goal>
   <goal name="search&#39;vc.33" expl="postcondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.083467" steps="447276"/></proof>
+  <proof prover="1"><result status="valid" time="0.912981" steps="3038114"/></proof>
   </goal>
   <goal name="search&#39;vc.34" expl="postcondition" proved="true">
-  <proof prover="0"><result status="valid" time="0.046369" steps="285721"/></proof>
+  <proof prover="1"><result status="valid" time="0.050621" steps="262231"/></proof>
   </goal>
  </transf>
  </goal>
diff --git a/creusot/tests/should_succeed/vector/08_haystack/why3shapes.gz b/creusot/tests/should_succeed/vector/08_haystack/why3shapes.gz
index 68991feb1..3611e1c8a 100644
Binary files a/creusot/tests/should_succeed/vector/08_haystack/why3shapes.gz and b/creusot/tests/should_succeed/vector/08_haystack/why3shapes.gz differ
diff --git a/creusot/tests/should_succeed/vector/09_capacity/why3session.xml b/creusot/tests/should_succeed/vector/09_capacity/why3session.xml
index b4d02c4c5..185c194ba 100644
--- a/creusot/tests/should_succeed/vector/09_capacity/why3session.xml
+++ b/creusot/tests/should_succeed/vector/09_capacity/why3session.xml
@@ -2,17 +2,17 @@
 <!DOCTYPE why3session PUBLIC "-//Why3//proof session v5//EN"
 "http://why3.lri.fr/why3session.dtd">
 <why3session shape_version="6">
-<prover id="1" name="Alt-Ergo" version="2.4.2" timelimit="1" steplimit="0" memlimit="1000"/>
+<prover id="0" name="Alt-Ergo" version="2.4.3" timelimit="1" steplimit="0" memlimit="1000"/>
 <file format="mlcfg" proved="true">
 <path name=".."/><path name="09_capacity.mlcfg"/>
 <theory name="C09Capacity_ChangeCapacity" proved="true">
  <goal name="change_capacity&#39;vc" expl="VC for change_capacity" proved="true">
- <proof prover="1"><result status="valid" time="0.045134" steps="269"/></proof>
+ <proof prover="0"><result status="valid" time="0.045134" steps="268"/></proof>
  </goal>
 </theory>
 <theory name="C09Capacity_ClearVec" proved="true">
  <goal name="clear_vec&#39;vc" expl="VC for clear_vec" proved="true">
- <proof prover="1"><result status="valid" time="0.014807" steps="23"/></proof>
+ <proof prover="0"><result status="valid" time="0.014807" steps="21"/></proof>
  </goal>
 </theory>
 </file>
diff --git a/creusot/tests/should_succeed/vector/09_capacity/why3shapes.gz b/creusot/tests/should_succeed/vector/09_capacity/why3shapes.gz
index cc7bc69a4..641262ce7 100644
Binary files a/creusot/tests/should_succeed/vector/09_capacity/why3shapes.gz and b/creusot/tests/should_succeed/vector/09_capacity/why3shapes.gz differ