proposition: Lemma qisom_restr_proof : setT \subset 'N(H) / G.
proof: Proof. by rewrite eqGH im_quotient. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq div) mathcomp(choice fintype prime finset fingroup morphism) mathcomp(automorphism)