From b609e0233a084a40e2f6ed4c9df056dfb6b0a2b1 Mon Sep 17 00:00:00 2001
From: "Wesley H. Holliday" <wesholliday@berkeley.edu>
Date: Thu, 2 May 2024 21:46:03 -0700
Subject: [PATCH 1/4] Fixed bug in has_positive_involvement_violation

---
 pref_voting/variable_voter_axioms.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pref_voting/variable_voter_axioms.py b/pref_voting/variable_voter_axioms.py
index a88d0f7..052eebd 100644
--- a/pref_voting/variable_voter_axioms.py
+++ b/pref_voting/variable_voter_axioms.py
@@ -275,7 +275,7 @@ def has_positive_involvement_violation(prof, vm, verbose=False, violation_type="
         if uniform_coalition:
             for loser in losers:
 
-                relevant_ranking_types = [r for r in prof.ranking_types if prof.rankings.count(r) >= coalition_size]
+                relevant_ranking_types = [r for r in prof.ranking_types if r[0] == loser and prof.rankings.count(r) >= coalition_size]
 
                 for r in relevant_ranking_types:
 

From 18345c3eef5585ecdac64ca72a5c73fddaa8da16 Mon Sep 17 00:00:00 2001
From: "Wesley H. Holliday" <wesholliday@berkeley.edu>
Date: Thu, 2 May 2024 22:12:16 -0700
Subject: [PATCH 2/4] Fixed bug in has_smith_violation and
 find_all_smith_violations

---
 pref_voting/dominance_axioms.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pref_voting/dominance_axioms.py b/pref_voting/dominance_axioms.py
index f05a18c..9edb01c 100644
--- a/pref_voting/dominance_axioms.py
+++ b/pref_voting/dominance_axioms.py
@@ -230,7 +230,7 @@ def has_smith_violation(edata, vm, verbose=False):
     s_set = smith_set(edata)
     ws = vm(edata)
 
-    winners_not_in_smith = [w not in s_set for w in ws]
+    winners_not_in_smith = [w for w in ws if w not in s_set]
     if len(winners_not_in_smith) > 0: 
         if verbose:
             if type(edata) == Profile or type(edata) == ProfileWithTies: 
@@ -259,7 +259,7 @@ def find_all_smith_violations(edata, vm, verbose=False):
     s_set = smith_set(edata)
     ws = vm(edata)
 
-    winners_not_in_smith = [w not in s_set for w in ws]
+    winners_not_in_smith = [w for w in ws if w not in s_set]
     if len(winners_not_in_smith) > 0: 
         if verbose:
             if type(edata) == Profile or type(edata) == ProfileWithTies: 

From 977059910a7511c61e3423277c7e23a74744b96a Mon Sep 17 00:00:00 2001
From: "Wesley H. Holliday" <wesholliday@berkeley.edu>
Date: Thu, 2 May 2024 22:28:34 -0700
Subject: [PATCH 3/4] Added Tideman's Preliminary Weighted Condorcet rule

---
 pref_voting/other_methods.py | 49 ++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/pref_voting/other_methods.py b/pref_voting/other_methods.py
index 1781f7e..d8117e5 100644
--- a/pref_voting/other_methods.py
+++ b/pref_voting/other_methods.py
@@ -198,6 +198,53 @@ def kemeny_young(profile, curr_cands = None):
     
     return sorted(list(set([r[0] for r in ky_rankings])))
 
+
+@vm("Preliminary Weighted Condorcet")
+def preliminary_weighted_condorcet(prof, curr_cands = None, show_orders = False, require_positive_plurality_score = False):
+    """The preliminary version of the Weighted Condorcet Rule in Tideman's book, Collective Decisions and Voting (p. 223). The winners are the candidates ranked first by some linear order of the candidates with highest score, where the score of an order (c_1,...,c_n) is the sum over all i<j of the margin of c_i vs. c_j multiplied by the plurality scores of c_i and c_j. 
+    
+    The multiplication by plurality scores is what distinguishes this method from the Kemeny-Young method.
+    
+    Tideman (p. 224) defines a more complicated Weighted Condorcet rule that is intended to be used when some candidates receive zero first-place votes.
+    
+    Args:
+        prof (Profile): An anonymous profile of linear orders on a set of candidates
+        curr_cands (List[int], optional): If set, then find the winners for the profile restricted to the candidates in ``curr_cands``
+        show_orders (bool): If True, then print the set of best orders.
+        require_positive_plurality_score (bool): If True, then require that all candidates have a positive plurality score.
+
+    Returns:
+        A sorted list of candidates
+    """
+
+    cands = curr_cands if curr_cands is not None else prof.candidates
+
+    if require_positive_plurality_score:
+        assert all([prof.plurality_scores(curr_cands=curr_cands)[c] > 0 for c in cands]), "All candidates must have a positive plurality score."
+
+    best_order_score = 0
+    best_orders = []
+
+    for r in permutations(cands):
+
+        score_of_r = 0 
+        for i in r[:-1]:
+            for j in r[r.index(i)+1:]:
+                score_of_r += (prof.plurality_scores(curr_cands=curr_cands)[i] * prof.plurality_scores(curr_cands=curr_cands)[j] * prof.margin(i,j))
+
+        if score_of_r > best_order_score:
+            best_order_score = score_of_r
+            best_orders = [r]
+        if score_of_r == best_order_score:
+            best_orders.append(r)
+
+    if show_orders == True:
+        print(f"Best orders: {set(best_orders)}")
+
+    winners = [r[0] for r in best_orders]
+
+    return list(set(winners))
+
 ### Bucklin
 
 @vm(name = "Bucklin")
@@ -558,6 +605,8 @@ def superior_voting(profile, curr_cands = None):
 
 other_vms = [
     kemeny_young, 
+    pareto,
+    preliminary_weighted_condorcet,
     majority, 
     bucklin,
     simplified_bucklin,

From 5c28732a4e91b3952fc8c5eddd9defdeee059019 Mon Sep 17 00:00:00 2001
From: "Wesley H. Holliday" <wesholliday@berkeley.edu>
Date: Thu, 2 May 2024 22:29:49 -0700
Subject: [PATCH 4/4] Update other_methods.md

---
 docs/source/other_methods.md | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/docs/source/other_methods.md b/docs/source/other_methods.md
index 7a88f33..2332400 100644
--- a/docs/source/other_methods.md
+++ b/docs/source/other_methods.md
@@ -10,7 +10,6 @@ Other Methods
 ```
 
 
-
 ## Kemeny-Young
 
 ```{eval-rst}
@@ -28,6 +27,14 @@ Other Methods
 
 ```
 
+## Preliminary Weighted Condorcet
+
+```{eval-rst}
+
+.. autofunction:: pref_voting.other_methods.preliminary_weighted_condorcet
+
+```
+
 ## Bucklin
 
 ```{eval-rst}