proposition: Lemma actKVin : {in D, rev_right_loop invg to}.
proof: Proof. by move=> a Da /= x; rewrite -{2}(invgK a) actKin ?groupV. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient)