Qed.
Hint Resolve ltT_not_eqT eqT_not_ltT ltT_not_refl.

(* Specifications: *)
Lemma ltT_not_ltT : forall x y : Term A n, ltT x y -> ~ ltT y x.
intros x y H'; red in |- *; intros H'0; absurd (ltT x x); auto.