Proof using.
induction l; intros.
- contradiction.
- destruct l'; try congruence.
find_copy_apply_lem_hyp prefix_sorted; auto. simpl in *. intuition.
+ left. subst. reflexivity.
+ right. subst. destruct l'.
* find_apply_lem_hyp contiguous_index_singleton.
specialize (H0 e). concludes. omega.
* eapply IHl; try discriminate; eauto. eapply cons_contiguous_sorted; eauto.
simpl in *. intuition.
Qed.

Lemma removeAfterIndex_contiguous :
forall l i i',
sorted l ->
contiguous_range_exact_lo l i ->
contiguous_range_exact_lo (removeAfterIndex l i') i.