proposition: Lemma lead_coef_proper_mul p q : let c := lead_coef p * lead_coef q in c != 0 -> lead_coef (p * q) = c.
proof: Proof. by move=> /= nz_c; rewrite mul_lead_coef -size_proper_mul. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)