Remark add_reduce : forall x : Z, (x > 0)%Z -> (x + 1 - 1 > 0)%Z.

(* Specifications: *)
Lemma safety1 : forall c : Config, legal c -> forall s : Site, s <> owner -> rt c s = true -> (st c owner > 0)%Z.
Lemma safety2 : forall c : Config, legal c -> forall s1 s2 : Site, In_queue Message copy (bm c s1 s2) -> (st c owner > 0)%Z.
Lemma safety1 : forall c : Config, legal c -> forall s : Site, s <> owner -> rt c s = true -> (st c owner > 0)%Z.
Lemma safety2 : forall c : Config, legal c -> forall s1 s2 : Site, In_queue Message copy (bm c s1 s2) -> (st c owner > 0)%Z.