proposition: Lemma quotient_pHall : K \subset 'N(H) -> pi.-Hall(G) K -> pi.-Hall(G / H) (K / H).
proof: Proof. exact: morphim_pHall. 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)