Definition ge (x y: t) :=
    match x, y with
    | OK a, OK b => EqSet.Subset b a
    | Error _, _ => True
    | _, Error _ => False
    end.

(* Specifications: *)
Lemma ge_refl: forall x y, eq x y -> ge x y.
Lemma ge_trans: forall x y z, ge x y -> ge y z -> ge x z.