As a simple-minded user I stumbled over exactly this last week. I don't understand much of what this thread is discussing, but I know what a simple-minded user wants.
sage: G = GL(2,13) sage: G = G.as_matrix_group() sage: H = G.subgroup([ matrix(GF(13),[[1,0],[1,1]]) ]) sage: H2 = G.subgroup([ matrix(GF(13),[[1,1],[0,1]]) ]) sage: H3 = G.subgroup([ matrix(GF(13),[[1,0],[2,1]]) ]) I expect H == H3 to say True as they are the same subgroup. I expect H = H2 to say False, since they are not the same subgroup, even though they are isomorphic. Instead sage: H == H3 False sage: matrix(GF(13),[[1,0],[1,1]]) in H3 True sage: matrix(GF(13),[[1,0],[2,1]]) in H True sage: H.is_isomorphic(H3) True sage: H.is_isomorphic(H2) True sage: matrix(GF(13),[[1,0],[1,1]]) in H2 False I though of working around it by checking if they are the same as sets, but to my surprise: sage: Set( h for h in H ) == Set( h for h in H3 ) False sage: Set( h.matrix() for h in H ) == Set( h.matrix() for h in H3 ) True In short: I consider this a bug. No matter how this is done at the back, the user expects == to mean mathematical equality, here equality of subgroups. Otherwise the function should be called subgroups_with_given_generators. Chris -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
