proposition: Lemma suber_ge0 y x : y \is a fin_num -> (0 <= x - y) = (y <= x).
proof: Proof. by move: x y => [x| |] [y| |] //= _; rewrite ?(leey, lee_fin, subr_ge0). Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed