IsIsomorphicSemigroup returns incorrect results when using graph isomorphism

Issue #96 resolved
Attila Egri-Nagy
created an issue

These two semigroups are conjugate as transformation semigroups but the graph isomorphism fails for them.

gap> Generators(S);
[ Transformation( [ 1, 2, 1 ] ), Transformation( [ 1, 2, 3, 2 ] ), 
  Transformation( [ 2, 2, 2 ] ), Transformation( [ 4, 2, 1, 4 ] ) ]
gap> Generators(T);
[ Transformation( [ 1, 2, 3, 1 ] ), Transformation( [ 2, 2, 3, 1 ] ), 
  Transformation( [ 2, 3, 3, 1 ] ), Transformation( [ 1, 3, 3 ] ), 
  Transformation( [ 2, 3, 3, 3 ] ), Transformation( [ 3, 2, 3, 3 ] ) ]

This code returns fail, though the partial order of D classes are isomorphic.

   pS:=Graph(Group(()), [1..NrDClasses(S)], OnPoints,
     function(i,j)
       return i in PartialOrderOfDClasses(S)[j];
     end, true);

    pT:=Graph(Group(()), [1..NrDClasses(T)], OnPoints,
     function(i,j)
       return i in PartialOrderOfDClasses(T)[j];
     end, true);

    iso:=GraphIsomorphism(pS, pT);

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