Fixpoint Ulist (n:nat) :=
  match n with
  | 0 => nil
  | S n' => U :: Ulist n'
  end.

(* Specifications: *)
Lemma ULTyped' : forall e n, isULTerm e -> closed' n e -> Typ (Ulist n) e U.
Theorem ULTyped : forall e, closed e /\ isULTerm e -> Typ nil e U.