Proof using.
intros a b; generalize a; elim b; clear a b; simpl in |- *; auto.
intros a a0 H; inversion H; auto.
intros p H p0 H0 a H1.
inversion H1; auto.
Qed.

(* Specifications: *)
(* The list of all leaves does not change *)
Theorem to_btree_all_leaves :
forall t, all_leaves (to_btree t) = all_pbleaves t.