proposition: Lemma lteif_nM2l C x : x < 0 -> {mono *%R x : y z /~ y < z ?<= if C}.
proof: Proof. by case: C => ? ? ?; rewrite /= lter_nM2l. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)