proposition: Lemma comm_polyD p q x: comm_poly p x -> comm_poly q x -> comm_poly (p + q) x.
proof: Proof. by rewrite /comm_poly hornerD mulrDr mulrDl => -> ->. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)