proposition: Lemma gte_daddl x y : x \is a fin_num -> (x + y < x) = (y < 0).
proof: Proof. by rewrite -fin_numN dual_addeE lteNl -[0]oppe0 lteNr; exact: lteDl. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed