proposition: Lemma horner_morphX : horner_morph cfu 'X = u.
proof: Proof. by rewrite /horner_morph map_polyX hornerX. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)