Dear Masoud, You could look the following GAP session:
gap> G:=DihedralGroup(32); gap> H:=NormalSubgroups(G)[2]; ## H is a normal subgroup of G gap> p:=NaturalHomomorphismByNormalSubgroup(G,H); ## p: G->G/H gap> GH:=Range(p); ## GH is the quotient G/H gap> A:=AutomorphismGroup(G); ## A=AutG gap> a:=Random(A); ## f is a element in AutG gap> gH:=List(GH,x->PreImagesRepresentative(p,x)); ##gH is the list of representatives {g_1,g_2,...,g_n} gap> agH:=List(gH,x->x^a); ## agH:={g_1^a,g_2^a,...,g_n^a} gap> aGH:=List(agH,x->x^p); Then aGH is the list that you want to compute Best regards, Luyen _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum