proposition: Lemma pquotient_pgroup : G \subset 'N(K) -> pi.-group (G / K) = pi.-group G.
proof: Proof. by move=> nKG; rewrite pmorphim_pgroup ?ker_coset. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(fintype bigop finset prime fingroup morphism) mathcomp(gfunctor automorphism quotient action gproduct) mathcomp(cyclic)