proposition: Lemma horner_comp p q x : (p \Po q).[x] = p.[q.[x]].
proof: Proof. by apply: polyC_inj; rewrite -!comp_polyCr comp_polyA. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)