proposition: Lemma eq_p'Hall pi rho G H : pi =i rho -> pi^'.-Hall(G) H = rho^'.-Hall(G) H.
proof: Proof. by move=> eq_pi_rho; apply: eq_pHall (eq_negn _). 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)