proposition: Lemma lteDl y x : y \is a fin_num -> (y < y + x) = (0 < x).
proof: Proof. by move: x y => [x| |] [y| |] _ //; rewrite ?ltry ?ltNyr // !lte_fin ltrDl. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed