proposition: Lemma comm_polyX x : comm_poly 'X x.
proof: Proof. by rewrite /comm_poly !hornerX. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)