GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
############################################################################# ## #W cat1.g XMODALG example files Zekeriya Arvasi #W & Alper Odabas ## version 1.12, 10/11/2015 ## #Y Copyright (C) 2014-2015, Zekeriya Arvasi & Alper Odabas, ## Print("\nXModAlg test file cat1.g (version 10/11/15) :-"); Print("\ntesting constructions of cat1-algebras\n\n"); A := GroupRing(GF(2),Group((1,2,3)(4,5))); R := GroupRing(GF(2),Group((1,2,3))); f := AllHomsOfAlgebras(A,R); g := AllHomsOfAlgebras(R,A); C4 := PreCat1ByTailHeadEmbedding(f[6],f[6],g[8]); IsCat1Algebra(C4); Size(C4); Display(C4); C2 := Cat1AlgebraSelect( 4, 6, 2, 2 ); Size( C2 ); Display( C2 ); C := Cat1AlgebraSelect(11); C := Cat1AlgebraSelect(4,12); C := Cat1AlgebraSelect(2,6,3); C := Cat1AlgebraSelect(2,6,2); C3 := Cat1AlgebraSelect( 2, 6, 2, 4 );; A3 := Source( C3 ); B3 := Range( C3 ); eA3 := Elements( A3 );; eB3 := Elements( B3 );; AA3 := Subalgebra( A3, [ eA3[1], eA3[2], eA3[3] ] ); [ Size(A3), Size(AA3) ]; BB3 := Subalgebra( B3, [ eB3[1], eB3[2] ] ); [ Size(B3), Size(BB3) ]; CC3 := SubCat1Algebra( C3, AA3, BB3 ); Display( CC3 ); C4 := Cat1AlgebraSelect( 2, 1, 1, 1 ); G := SmallGroup(4,2); F := GaloisField(4); R := GroupRing( F, G ); Size(R); SetName( R, "GF(2^2)[k4]" ); e5 := Elements(R)[5]; S := Subalgebra( R, [e5] ); SetName( S, "<e5>" ); RS := Cartesian( R, S );; SetName( RS, "GF(2^2)[k4] x <e5>" ); act := AlgebraAction( R, RS, S );; bdy := AlgebraHomomorphismByFunction( S, R, r->r ); IsAlgebraAction( act ); IsAlgebraHomomorphism( bdy ); XM := PreXModAlgebraByBoundaryAndAction( bdy, act ); CXM := Cat1AlgebraByXModAlgebra( XM ); Display(CXM); X3 := XModAlgebraByCat1Algebra( C3 ); Display( X3 ); ############################################################################# ## #E cat1.g . . . . . . . . . . . . . . . . . . . . . . . . . . . ends here