proposition: Lemma drop_polyZ k m p : drop_poly m (k *: p) = k *: drop_poly m p.
proof: Proof. by apply/polyP => i; rewrite coefZ !coef_drop_poly coefZ. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)