Section DEL_ALT.
(* structure de file d'attente *)
Variable c0 : Config.
Variable s0 s1 : Site.

Lemma del_trans_D :
(rt c0 s0 = false -> D_queue (bm c0 s0 owner)) ->
rt (delete_trans c0 s1) s0 = false ->
D_queue (bm (delete_trans c0 s1) s0 owner).