proposition: Lemma card_conjugates A G : #|A :^: G| = #|G : 'N_G(A)|.
proof: Proof. by rewrite card_orbit astab1Js. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient)