End ALTERNATE.
Section MESS_ALT.
(* consequence sur la structure alternee *)
Variable b0 : Bag_of_Data Message.
Variable s0 : Site.

Lemma alt_post_any :
forall m : Message,
(forall s : Site, m <> inc_dec s) ->
alternate (b0 s0 owner) ->
alternate (Post_message Message m b0 s0 owner s0 owner).