proposition: Lemma dsubre_le0 y x : y \is a fin_num -> (y - x <= 0) = (y <= x).
proof: Proof. by move=> ?; rewrite dual_addeE oppe_le0 subre_ge0 ?fin_numN// leeN2. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed