proposition: Lemma even_polyD p q : even_poly (p + q) = even_poly p + even_poly q.
proof: Proof. by apply/polyP => i; rewrite !(coef_even_poly, coefD). Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)