proposition: Lemma ler_wpM2l x : 0 <= x -> {homo *%R x : y z / y <= z}.
proof: Proof. by rewrite le0r => /orP[/eqP-> y z | /ler_pM2l/mono2W//]; rewrite !mul0r. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)