Dear Mr. Sorouhesh, I believe the command IntermediateSubgroups does what you want. Here's an example (where I'm calling your "fixed" subgroup H):
gap> G := SymmetricGroup(4);; gap> ccsg := ConjugacyClassesSubgroups(G);; gap> H := Representative(ccsg[5]);; # the Klein-4 group gap> intHG := IntermediateSubgroups(G,H); rec( subgroups := [ Group([ (1,4)(2,3), (1,3)(2,4), (3,4) ]), Group([ (1,4)(2,3), (1,3)(2,4), (2,3) ]), Group([ (1,4)(2,3), (1,3)(2,4), (2,4) ]), Group([ (1,4)(2,3), (1,3)(2,4), (2,4,3) ]) ], inclusions := [ [ 0, 1 ], [ 0, 2 ], [ 0, 3 ], [ 0, 4 ], [ 1, 5 ], [ 2, 5 ], [ 3, 5 ], [ 4, 5 ] ] ) The subgroups field of the intHG structure gives the list of subgroups of G that contain H. You can access the i-th intermediate subgroup using intHG.subgroups[i]. (Note that H and G are not included in the intHG.subgroups list.) The inclusions field gives the lattice of intermediate subgroups by showing the covering relations. -William On Sun, May 13, 2012 at 9:44 PM, Mr. Sorouhesh <msorouh...@gmail.com> wrote: > Suppose we have a finite group such that know all its subgroups. Now, > fix a certain subgroup in the group.Can we use GAP to list all > subgroups of the group that contain our fixed subgroup? > Best > > _______________________________________________ > Forum mailing list > Forum@mail.gap-system.org > http://mail.gap-system.org/mailman/listinfo/forum -- William J. DeMeo Department of Mathematics University of Hawaii at Manoa phone: 808-298-4874 url: http://math.hawaii.edu/~williamdemeo _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum