proposition: Lemma comm_poly_exp p n x: comm_poly p x -> comm_poly (p ^+ n) x.
proof: Proof. by move=> px; rewrite /comm_poly !horner_exp_comm// commrX. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)