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