proposition: Lemma afixYin A B : A \subset D -> B \subset D -> 'Fix_to(A <*> B) = 'Fix_to(A) :&: 'Fix_to(B).
proof: Proof. by move=> sAD sBD; rewrite afix_gen_in ?afixU // subUset sAD. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient)