proposition: Lemma ltr_nMz2l x (hx : x < 0) : {mono *~%R x : x y /~ x < y}.
proof: Proof. exact: leW_nmono (ler_nMz2l _). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)