From 79d230fe7c3dff45b30dfca341b77bd0f4974fce Mon Sep 17 00:00:00 2001
From: Tom Conti-Leslie <tom.contileslie@gmail.com>
Date: Wed, 19 May 2021 17:14:35 +0200
Subject: [PATCH] Add IsOrthoGroup property

---
 gap/attributes/properties.gd | 3 +++
 gap/attributes/properties.gi | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/gap/attributes/properties.gd b/gap/attributes/properties.gd
index a1c763f2b..1d46f37bf 100644
--- a/gap/attributes/properties.gd
+++ b/gap/attributes/properties.gd
@@ -102,3 +102,6 @@ DeclareProperty("IsSurjectiveSemigroup", IsSemigroup);
 InstallTrueMethod(IsSurjectiveSemigroup, IsRegularSemigroup);
 InstallTrueMethod(IsSurjectiveSemigroup, IsMonoidAsSemigroup);
 InstallTrueMethod(IsSurjectiveSemigroup, IsIdempotentGenerated);
+
+DeclareProperty("IsOrthogroup", IsSemigroup);
+DeclareSynonym("IsOrthoGroup", IsOrthogroup);
diff --git a/gap/attributes/properties.gi b/gap/attributes/properties.gi
index ab588cfcf..9bea4e492 100644
--- a/gap/attributes/properties.gi
+++ b/gap/attributes/properties.gi
@@ -1784,3 +1784,9 @@ x -> UnderlyingSemigroupOfSemigroupWithAdjoinedZero(x) <> fail);
 InstallMethod(IsSurjectiveSemigroup, "for a semigroup",
 [IsSemigroup],
 S -> IsEmpty(IndecomposableElements(S)));
+
+InstallMethod(IsOrthogroup, "for a semigroup",
+[IsSemigroup],
+function(S)
+  return IsCompletelyRegularSemigroup(S) and IsOrthodoxSemigroup(S);
+end);