Definition delete_trans (c : Config) (s : Site) :=
  mkconfig (S (time c)) (dt c) (st c) (Reset_rec_table (rt c) s)
    (Post_message dec (bm c) s owner).

Lemma del_trans_diff_site : forall s3 s4 : Site, (In_queue Message copy (bm c0 s3 s4) -> s3 <> s4) -> In_queue Message copy (bm (delete_trans c0 s0) s3 s4) -> s3 <> s4.