proposition: Lemma lee_suber_addr x y z : y \is a fin_num -> (x <= y - z) = (x + z <= y).
proof: Proof. move: y x z => [y| |] [x| |] [z| |] _ //=; rewrite ?leNye ?leey //. by rewrite !lee_fin lerBrDr. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed