proposition: Lemma restrm_quotientE G A (nHG : G \subset 'N(H)) : A \subset G -> restrm nHG (coset H) @* A = A / H.
proof: Proof. exact: restrmEsub. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq div) mathcomp(choice fintype prime finset fingroup morphism) mathcomp(automorphism)