Proof using.
destruct l'.
- intros. simpl in *. rewrite app_nil_r in *.
eapply_prop (contiguous_range_exact_lo l). omega.
- intros. find_eapply_lem_hyp contiguous_app_prefix_contiguous; eauto.
left. intuition. congruence.
Qed.

(* Specifications: *)
Lemma contiguous_0_app :
forall l1 l2 e,
sorted (l1 ++ l2) ->
contiguous_range_exact_lo (l1 ++ l2) 0 ->
In e l1 ->
eIndex e > maxIndex l2.