proposition: Lemma lead_coefDr p q : size q > size p -> lead_coef (p + q) = lead_coef q.
proof: Proof. by move/lead_coefDl<-; rewrite addrC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)