Dera Hung, Dear Forum, Yes, you can do it with cohomolo. cohomolo works only with permutation groups, and you have to do the calculation one prime at at a time.
gap> LoadPackage("cohomolo"); true gap> G:=GL(3,4);; gap> P:=Image(IsomorphismPermGroup(G)); <permutation group of size 181440 with 2 generators> gap> C:=CHR(P,2);; SchurMultiplier(C); [ ] gap> C:=CHR(P,3);; SchurMultiplier(C); [ ] gap> C:=CHR(P,5);; SchurMultiplier(C); The Sylow p-subgroup of the group is cyclic - so the multiplier is trivial. [ ] gap> C:=CHR(P,7);; SchurMultiplier(C); The Sylow p-subgroup of the group is cyclic - so the multiplier is trivial. [ ] So the Schur multiplier of GL(3,4) is trivial. (SL(3,4) on the other hand has multiplier 4 X 4, but the outer automorphism of SL(3,4) of order 3 induces a fixed-point-free action on this group, and hence kills it in GL(3,4).) Derek. > Dear Forum, > > I am trying to compute the Schur multiplier of GL(3,4) and here is what I got: > > >G:=GeneralLinearGroup(3,4); > [GL(3,4) > >AbelianInvariantsMultiplier(G); > [Error, the coset enumeration has defined more than 256000 cosets > > I just wonder if we can do it by using the ''cohomolo'' package and working > under UNIX/LINUX systems? > > Thank you very much for your help, > Hung. > _______________________________________________ > Forum mailing list > Forum@mail.gap-system.org > http://mail.gap-system.org/mailman/listinfo/forum _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum