proposition: Lemma dsuber_le0 x y : y \is a fin_num -> (x - y <= 0) = (x <= y).
proof: Proof. by move=> ?; rewrite dual_addeE oppe_le0 suber_ge0 ?fin_numN// leeN2. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed