proposition: Lemma cosetpre_cent A : 'C_('N(H))(A) \subset coset H @*^-1 'C(A / H).
proof: Proof. exact: morphpre_cent. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq div) mathcomp(choice fintype prime finset fingroup morphism) mathcomp(automorphism)