proposition: Lemma horner_cons p c x : (cons_poly c p).[x] = p.[x] * x + c.
proof: Proof. rewrite /horner polyseq_cons; case: nilP => //= ->. by rewrite !simp -/(_.[x]) hornerC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)