proposition: Lemma lreg_lead0 p : GRing.lreg (lead_coef p) -> p != 0.
proof: Proof. by move/lreg_neq0; rewrite lead_coef_eq0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)