Proof using.
intros. subst. intuition.
Qed.

(* Specifications: *)
Lemma app_contiguous_maxIndex_le_eq :
forall l l1 l2 l2' i,
l = l1 ++ l2 ->
Prefix l2 l2' ->
contiguous_range_exact_lo l i ->
maxIndex l2' <= i ->
l = l1.