Section BUT_OWNER.
Variable Data : Set.
Let Table := Site -> Data.
Variable f : Site -> Data -> Z.
Definition sigma_table_but_owner (st : Table) :=
sigma_but Site owner eq_site_dec LS (fun s : Site => f s (st s)).

Lemma sigma_sigma_but_owner :
forall t : Table,
sigma_table Site LS Data f t =
(sigma_table_but_owner t + f owner (t owner))%Z.