proposition: Lemma pmulrz_lge0 x n (n0 : 0 < n) : 0 <= x *~ n = (0 <= x).
proof: Proof. by rewrite -(mul0rz _ n) ler_pMz2r // mul0rz. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)