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cdwensley merged 1 commit into from
Dec 10, 2025
Merged

adjust to changes in groupoids #159

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2 changes: 1 addition & 1 deletion CHANGES.md
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
## CHANGES to the 'XMod' package

## 2.96 -> 2.97-dev (04/12/2025)
## 2.96 -> 2.97 (10/12/2025)
* (04/12/25) remove various unused categories etc in dom2dnd.gd
* (03/12/25) comment out use of Ancestor - it is no longer defined in groupoids

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33 changes: 17 additions & 16 deletions doc/gpd2obj.xml
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Expand Up @@ -57,15 +57,16 @@ In the example the crossed module <C>DX4</C> has discrete source,
while the crossed module <C>CX4</C> has connected source.
These are groupoid generalisations of <Ref Oper="XModByNormalSubgroup"/>
and the example <C>X4</C> in <Ref Oper="NormalSubXMods"/>.
<P/>
These calculations are WRONG!
Need more investigation of <C>XModAction</C>.
<!-- ------------------------------------------------------------------- -->
<!-- At one time I thought that: These calculations are WRONG! -->
<!-- and: Need more investigation of <C>XModAction</C>. -->
<!-- but they do seem to be correct after all! -->
<!-- ------------------------------------------------------------------- -->
</Description>
</ManSection>
<P/>
<Example>
<![CDATA[
gap> X4 := XModByNormalSubgroup( s4, a4 );;
gap> CX4 := SinglePiecePreXModWithObjects( X4, [-6,-5,-4], false );
single piece precrossed module with objects
source groupoid:
Expand Down Expand Up @@ -102,7 +103,7 @@ The precrossed module <C>CX4</C> belongs to the category
<P/>
<Example>
<![CDATA[
gap> Set( KnownPropertiesOfObject( CX4 ) );
gap> Set( KnownPropertiesOfObject( CX4 ) );
[ "CanEasilyCompareElements", "CanEasilySortElements", "IsAssociative",
"IsDuplicateFree", "IsGeneratorsOfSemigroup", "IsPreXModWithObjects",
"IsSinglePieceDomain", "IsXModWithObjects" ]
Expand All @@ -127,7 +128,7 @@ they were constructed.
<![CDATA[
gap> IsPermPreXModWithObjects( CX4 );
true
gap> IsPcPreXModWithObjects( CX4 );
gap> IsPcPreXModWithObjects( CX4 );
false
gap> IsFpPreXModWithObjects( CX4 );
false
Expand All @@ -142,8 +143,8 @@ false
<Description>
<Index>ObjectList</Index>
The attributes of a precrossed module with objects include the standard
<C>Source</C>; <C>Range</C>;
<Ref Attr="Boundary" Label="for crossed modules"/>;
<C>Source</C>; <C>Range</C>;
<Ref Attr="Boundary" Label="for crossed modules"/>;
and <Ref Meth="XModAction" Label="for crossed modules of groups"/>
as with precrossed modules of groups.
There is also <C>ObjectList</C>,
Expand All @@ -160,13 +161,13 @@ where the group is the automorphism group of the range groupoid.
<P/>
<Example>
<![CDATA[
gap> Root2dGroup( CX4 );
gap> Root2dGroup( CX4 );
[a4->s4]
gap> actC := XModAction( CX4 );;
gap> Size( Range( actC ) );
gap> actC := XModAction( CX4 );;
gap> Size( Range( actC ) );
20736
gap> r1 := Arrow( Cs4, (1,2,3,4), -4, -5 );;
gap> ImageElm( actC, r1 );
gap> r1 := Arrow( Cs4, (1,2,3,4), -4, -5 );;
gap> ir1 := ImageElm( actC, r1 );
[groupoid homomorphism : Ca4 -> Ca4
[ [ [(1,2,3) : -6 -> -6], [(2,3,4) : -6 -> -6], [() : -6 -> -5],
[() : -6 -> -4] ],
Expand All @@ -177,12 +178,12 @@ gap> ## calculate s1^r1
gap> ims1 := ImageElmXModAction( CX4, s1, r1 );
[(1,2,3) : -6 -> -6]
gap> ## repeat using DX4
gap> actD := XModAction( DX4 );;
gap> actD := XModAction( DX4 );;
gap> SetName( Range( actD ), "autD" );
gap> Size( Range( actD ) );
82944
gap> r2 := Arrow( Ds4, (1,2,3,4), -7, -8 );;
gap> ImageElm( actD, r2 );
gap> r2 := Arrow( Ds4, (1,2,3,4), -7, -8 );;
gap> ImageElm( actD, r2 );
[groupoid homomorphism : Da4 -> Da4
: 0 -> 0]
gap> s2 := Arrow( Da4, (1,2,4), -8, -8 );;
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38 changes: 19 additions & 19 deletions tst/manual/gpd2obj.tst
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Expand Up @@ -5,20 +5,20 @@
#Y Copyright (C) 2001-2025, Chris Wensley et al,
##
gap> START_TEST( "XMod package: gpd2obj.tst" );
gap> saved_infolevel_xmod := InfoLevel( InfoXMod );;
gap> saved_infolevel_xmod := InfoLevel( InfoXMod );;
gap> SetInfoLevel( InfoXMod, 0 );;

## make this test independent of gp2obj.tst
gap> s4 := Group( (1,2), (2,3), (3,4) );;
gap> a4 := Subgroup( s4, [ (1,2,3), (2,3,4) ] );;
gap> SetName( s4, "s4" ); SetName( a4, "a4" );
gap> s4 := Group( (1,2), (2,3), (3,4) );;
gap> a4 := Subgroup( s4, [ (1,2,3), (2,3,4) ] );;
gap> SetName( s4, "s4" ); SetName( a4, "a4" );
gap> X4 := XModByNormalSubgroup( s4, a4 );;



## Chapter 10

## Subsection 10.1.1
## Subsection 10.1.2
gap> CX4 := SinglePiecePreXModWithObjects( X4, [-6,-5,-4], false );
single piece precrossed module with objects
source groupoid:
Expand All @@ -38,28 +38,28 @@ gap> SetName( DX4, "DX4" );
gap> Da4 := Source( DX4 );; SetName( Da4, "Da4" );
gap> Ds4 := Range( DX4 );; SetName( Ds4, "Ds4" );

## Subsection 10.1.2
gap> Set( KnownPropertiesOfObject( CX4 ) );
## Subsection 10.1.3
gap> Set( KnownPropertiesOfObject( CX4 ) );
[ "CanEasilyCompareElements", "CanEasilySortElements", "IsAssociative",
"IsDuplicateFree", "IsGeneratorsOfSemigroup", "IsPreXModWithObjects",
"IsSinglePieceDomain", "IsXModWithObjects" ]

## Subsection 10.1.3
## Subsection 10.1.4
gap> IsPermPreXModWithObjects( CX4 );
true
gap> IsPcPreXModWithObjects( CX4 );
gap> IsPcPreXModWithObjects( CX4 );
false
gap> IsFpPreXModWithObjects( CX4 );
false

## Subsection 10.1.4
gap> Root2dGroup( CX4 );
## Subsection 10.1.5
gap> Root2dGroup( CX4 );
[a4->s4]
gap> actC := XModAction( CX4 );;
gap> Size( Range( actC ) );
gap> actC := XModAction( CX4 );;
gap> Size( Range( actC ) );
20736
gap> r1 := Arrow( Cs4, (1,2,3,4), -4, -5 );;
gap> ImageElm( actC, r1 );
gap> r1 := Arrow( Cs4, (1,2,3,4), -4, -5 );;
gap> ir1 := ImageElm( actC, r1 );
[groupoid homomorphism : Ca4 -> Ca4
[ [ [(1,2,3) : -6 -> -6], [(2,3,4) : -6 -> -6], [() : -6 -> -5],
[() : -6 -> -4] ],
Expand All @@ -70,18 +70,18 @@ gap> ## calculate s1^r1
gap> ims1 := ImageElmXModAction( CX4, s1, r1 );
[(1,2,3) : -6 -> -6]
gap> ## repeat using DX4
gap> actD := XModAction( DX4 );;
gap> actD := XModAction( DX4 );;
gap> SetName( Range( actD ), "autD" );
gap> Size( Range( actD ) );
82944
gap> r2 := Arrow( Ds4, (1,2,3,4), -7, -8 );;
gap> ImageElm( actD, r2 );
gap> r2 := Arrow( Ds4, (1,2,3,4), -7, -8 );;
gap> ImageElm( actD, r2 );
[groupoid homomorphism : Da4 -> Da4
: 0 -> 0]
gap> s2 := Arrow( Da4, (1,2,4), -8, -8 );;
gap> ## calculate s2^r2
gap> ims2 := ImageElmXModAction( DX4, s2, r2 );
[(1,2,3) : -9 -> -9]

gap> SetInfoLevel( InfoXMod, saved_infolevel_xmod );;
gap> SetInfoLevel( InfoXMod, saved_infolevel_xmod );;
gap> STOP_TEST( "gpd2obj.tst", 10000 );