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.