proposition: Lemma coprime_sdprod_Hall_r G K H : K ><| H = G -> coprime #|K| #|H| = Hall G H.
proof: Proof. by move=> defG; rewrite (coprime_sdprod_Hall_l defG) (sdprod_Hall defG). 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)