proposition: Lemma dvdn_orbit G x : #|orbit to G x| %| #|G|.
proof: Proof. by rewrite card_orbit dvdn_indexg. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient)