proposition: Lemma im_actperm_Aut : actperm to @* D \subset Aut R.
proof: Proof. by apply/subsetP=> _ /morphimP[a _ Da ->]; apply: actperm_Aut. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient)