proposition: Lemma pmulrn_lle0 x n : (0 < n)%N -> (x *+ n <= 0) = (x <= 0).
proof: Proof. by move=> n_gt0; rewrite -(mul0rn _ n) ler_pMn2r // mul0rn. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)