intros x y z t p; case p; simpl in |- *; auto.
intros H'; injection H'; simpl in |- *; auto.
intros a l; case l; simpl in |- *; auto.
intros H'; discriminate H'.
intros a0 l0; case l0; simpl in |- *; auto.
intros H'; discriminate H'.
intros a1 l1 H'; discriminate H'.
Qed.

Theorem olist_ltT :
forall (l : list (Term A n)) (a b : Term A n),
olist (l ++ pX a (pX b pO)) -> ltT b a.