proposition: Lemma lee_dsubel_addl x y z : x \is a fin_num -> (x - y <= z) = (x <= y + z).
proof: Proof. by move=> ?; rewrite !dual_addeE leeNl leeNr lee_suber_addl ?fin_numN. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed