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