proposition: Lemma map_comm_poly p x : comm_poly p x -> comm_poly p^f (f x).
proof: Proof. by rewrite /comm_poly horner_map -!rmorphM // => ->. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)