From c239b9d0e1974eb1e9be6861fe252565c330194a Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 31 Oct 2023 13:35:20 +0000
Subject: [PATCH] Don't know

---
 gap/semigroups/semicons.gd |  2 ++
 gap/semigroups/semicons.gi | 22 +++++++++++++++++++++-
 gap/semigroups/semiex.gi   |  2 +-
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/gap/semigroups/semicons.gd b/gap/semigroups/semicons.gd
index 6a5c16d77..693e64de5 100644
--- a/gap/semigroups/semicons.gd
+++ b/gap/semigroups/semicons.gd
@@ -20,6 +20,8 @@ DeclareGlobalFunction("LeftZeroSemigroup");
 DeclareGlobalFunction("RightZeroSemigroup");
 DeclareConstructor("BrandtSemigroupCons", [IsSemigroup, IsGroup, IsPosInt]);
 DeclareGlobalFunction("BrandtSemigroup");
+DeclareConstructor("FreeSemilatticeCons", [IsSemigroup, IsPosInt]);
+DeclareGlobalFunction("FreeSemilattice");
 
 DeclareCategory("IsSSSE", IsAssociativeElement);
 DeclareCategoryCollections("IsSSSE");
diff --git a/gap/semigroups/semicons.gi b/gap/semigroups/semicons.gi
index 56dccef8d..7d8353615 100644
--- a/gap/semigroups/semicons.gi
+++ b/gap/semigroups/semicons.gi
@@ -718,7 +718,7 @@ function(arg)
     S := BrandtSemigroupCons(arg[1], arg[2], arg[3]);
   else
     ErrorNoReturn("the arguments must be a positive integer or a filter and",
-                   " a positive integer, or  a perm group and positive ",
+                   " a positive integer, or a perm group and positive ",
                    "integer, or a filter, perm group, and positive ",
                    "integer");
   fi;
@@ -796,6 +796,26 @@ for _IsXSemigroup in ["IsTransformationSemigroup",
 od;
 Unbind(_IsXSemigroup);
 
+InstallGlobalFunction(FreeSemilattice,
+function(arg)
+  local S;
+
+  if Length(arg) = 0 then
+    S := TrivialSemigroupCons(IsTransformationSemigroup, 0);
+  elif Length(arg) = 1 and IsInt(arg[1]) and arg[1] >= 0 then
+    S := TrivialSemigroupCons(IsTransformationSemigroup, arg[1]);
+  elif Length(arg) = 1 and IsOperation(arg[1]) then
+    S := TrivialSemigroupCons(arg[1], 0);
+  elif Length(arg) = 2 and IsOperation(arg[1]) and IsInt(arg[2])
+      and arg[2] >= 0 then
+    S := TrivialSemigroupCons(arg[1], arg[2]);
+  else
+    ErrorNoReturn("the arguments must be a non-negative integer or ",
+                  "a filter and a non-negative integer");
+  fi;
+  SetIsTrivial(S, true);
+  return S;
+end);
 InstallMethod(StrongSemilatticeOfSemigroups,
 "for a digraph, a list, and a list",
 [IsDigraph, IsList, IsList],
diff --git a/gap/semigroups/semiex.gi b/gap/semigroups/semiex.gi
index 3743b2298..ace6bd1ec 100644
--- a/gap/semigroups/semiex.gi
+++ b/gap/semigroups/semiex.gi
@@ -1,7 +1,7 @@
 #############################################################################
 ##
 ##  semigroups/semiex.gi
-##  Copyright (C) 2013-2022                               James D. Mitchell
+##  Copyright (C) 2013-2023                              James D. Mitchell
 ##
 ##  Licensing information can be found in the README file of this package.
 ##