proposition: Fact qact_subdomE : subdom = qact_dom.
proof: Proof. by congr 'N(_|_); apply/setP=> Hx; rewrite !inE genGid. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient)