proposition: Lemma leeDl x y : 0 <= y -> x <= x + y.
proof: Proof. move: x y => -[ x [y| |]//= | [| |]// | [| | ]//]; by [rewrite !lee_fin lerDl | move=> _; exact: leey]. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed