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

Theorem no_entries_past_current_term_nw_only_new_packets_matter :
forall net ps' l st',
no_entries_past_current_term_nw net ->
(forall p, In p ps' -> In p (nwPackets net) \/ In p l) ->
no_entries_past_current_term_nw (mkNetwork l st') ->
no_entries_past_current_term_nw (mkNetwork ps' st').