Proof using.
unfold logs_sorted_nw in *. intros.
simpl in *. find_apply_hyp_hyp. intuition eauto.
Qed.

(* Specifications: *)
Theorem packets_gt_prevIndex_packets_unchanged :
forall net ps' st',
packets_gt_prevIndex net ->
(forall p, In p ps' -> In p (nwPackets net) \/ False) ->
packets_gt_prevIndex (mkNetwork ps' st').