Definition Z_id (s : Site) (x : Z) := x.

Lemma sigma_table_simpl_property : forall (t1 t2 : Site -> Data) (P : (Site -> Data) -> Site -> Set), ((forall d : Site, P t2 d) -> t1 = t2) -> (forall d : Site, P t2 d) -> sigma_table Site LS Data f t1 = sigma_table Site LS Data f t2.