proposition: Lemma Frobenius_autMz x n : (x *~ n)^f = x^f *~ n.
proof: Proof. case: n=> n /=; first exact: Frobenius_autMn. by rewrite !NegzE !mulrNz Frobenius_autN Frobenius_autMn. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)