proposition: Lemma injm_quotm : 'injm f -> 'injm quotm.
proof: Proof. by move/trivgP=> /= kf1; rewrite ker_quotm kf1 quotientE morphim1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq div) mathcomp(choice fintype prime finset fingroup morphism) mathcomp(automorphism)