semifp: add missing methods for fp monoids/semigroups

doc/semifp.xml

@@ -1,7 +1,7 @@
 #############################################################################
 ##
 #W semifp.xml
-#Y Copyright (C) 2020 Luke Elliott
+#Y Copyright (C) 2020-2022 Luke Elliott
 ##
 ## Licensing information can be found in the README file of this package.
 ##
@@ -89,3 +89,28 @@ true]]></Example>
  </Description>
 </ManSection>
 <#/GAPDoc>
+
+<#GAPDoc Label="FreeMonoidAndAssignGeneratorVars">
+<ManSection>
+ <Func Name="FreeMonoidAndAssignGeneratorVars" Arg="arg..."/>
+ <Func Name="FreeSemigroupAndAssignGeneratorVars" Arg="arg..."/>
+ <Returns>A free semigroup or monoid.</Returns>
+ <Description>
+ <C>FreeMonoidAndAssignGeneratorVars</C> is synonym with:
+ <Log>
+ FreeMonoid(arg...);
+ AssignGeneratorVariables(last);</Log>
+ These functions exist so that the <C>String</C> method for a finitely
+ presented semigroup or monoid to be valid &GAP; input which can be used to
+ reconstruct the semigroup or monoid.
+ <Example><![CDATA[
+gap> F := FreeSemigroupAndAssignGeneratorVars("x", "y");;
+gap> IsBound(x);
+true
+gap> IsBound(y);
+true]]></Example>
+ </Description>
+</ManSection>
+<#/GAPDoc>
+
+

doc/z-chap15.xml

@@ -51,6 +51,7 @@
  <#Include Label = "ParseRelations">
  <#Include Label = "ElementOfFpSemigroup">
  <#Include Label = "ElementOfFpMonoid">
+ <#Include Label = "FreeMonoidAndAssignGeneratorVars">
  </Section>
 
  <Section Label="Creating Tietze transformation objects">

gap/semigroups/semifp.gd

@@ -15,3 +15,6 @@ DeclareAttribute("UnderlyingCongruence", IsFpSemigroup);
 DeclareAttribute("UnderlyingCongruence", IsFpMonoid);
 DeclareAttribute("Length", IsFpSemigroup);
 DeclareAttribute("Length", IsFpMonoid);
+
+DeclareGlobalFunction("FreeMonoidAndAssignGeneratorVars");
+DeclareGlobalFunction("FreeSemigroupAndAssignGeneratorVars");