proposition: Fact mul_polyDl : left_distributive mul_poly +%R.
proof: Proof. move=> p q r; apply/polyP=> i; rewrite coefD !coef_mul_poly -big_split. by apply: eq_bigr => j _; rewrite coefD mulrDl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)