proposition: Lemma actCJV a b x : to (to x a) b = to (to x (b ^ a^-1)) a.
proof: Proof. by rewrite (actCJ _ a) conjgKV. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient)