Section DEL_EFFECT.
(* invariants *)
Variable c0 : Config.
Variable s0 : Site.
Hypothesis rt_true : rt c0 s0 = true.

Lemma del_trans_le_dt_time :
forall s1 : Site,
dt c0 s1 <= time c0 ->
dt (delete_trans c0 s0) s1 <= time (delete_trans c0 s0).