GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
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#W sl25.g XMOD example files Chris Wensley
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#Y Copyright (C) 2001-2017, Chris Wensley et al,
#Y School of Computer Science, Bangor University, U.K.
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Print("\nXMod test file sl25.g (version 05/04/17) :-\n");
Print( "testing crossed modules of linear groups:\n\n" );
level := InfoLevel( InfoXMod );
SetInfoLevel( InfoXMod, 2 );
sl25pc := SpecialLinearGroup(2,5);
SetName( sl25pc, "sl25-pc" );
isosl := IsomorphismPermGroup( sl25pc );
sl25 := Image( isosl );
SetName( sl25, "sl25" );
gensl25 := GeneratorsOfGroup( sl25 );
Print( "sl25 has generators: ", gensl25, "\n" );
ccsl := ConjugacyClassesSubgroups( sl25 );
repssl := List( ccsl, c -> Representative(c) );
Print( "conj. classes: ", List( repssl, r -> Size(r) ), "\n" );
Print( List( repssl, r -> StructureDescription(r) ), "\n" );
gl25pc := GeneralLinearGroup(2,5);
SetName( gl25pc, "gl25-pc" );
isogl := IsomorphismPermGroup( gl25pc );
invgl := InverseGeneralMapping( isogl );
gl25 := Image( isogl );
SetName( gl25, "gl25" );
gengl25 := GeneratorsOfGroup( gl25 );
Print( "gl25 has generators: ", gengl25, "\n" );
ccgl := ConjugacyClassesSubgroups( gl25 );
repsgl := List( ccgl, c -> Representative(c) );
Print( "conj. classes: ", List( repsgl, r -> Size(r) ), "\n" );
Print( List( repsgl, r -> StructureDescription(r) ), "\n" );
lengl := Length( repsgl );
sl25c2 := repsgl[lengl-1];
SetName( sl25c2, "sl25.c2" );
X25 := XModByNormalSubgroup( sl25c2, sl25 );
inc25 := InclusionMappingGroups( gl25, sl25c2 );
indX25 := InducedXMod( X25, inc25 );
Display( indX25 );
h25 := Source( indX25 );
Print( "h25 = ", StructureDescription( h25 ), "\n" );
SetInfoLevel( InfoXMod, level );
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#E sl25.g . . . . . . . . . . . . . . . . . . . . . . . . . . . . ends here