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

Theorem packets_ge_prevTerm_packets_unchanged :
forall net ps' st',
packets_ge_prevTerm net ->
(forall p, In p ps' -> In p (nwPackets net) \/ False) ->
packets_ge_prevTerm (mkNetwork ps' st').