proposition: Lemma sube_lt0 x y : (x \is a fin_num) || (y \is a fin_num) -> (x - y < 0) = (x < y).
proof: Proof. by move=> /orP[?|?]; [rewrite subre_lt0|rewrite suber_lt0]. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed