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

(* Specifications: *)
Lemma owner_st_positive : forall c : Config, legal c -> (st c owner >= 0)%Z.
Lemma owner_st_positive : forall c : Config, legal c -> (st c owner >= 0)%Z.
Lemma owner_st_positive : forall c : Config, legal c -> (st c owner >= 0)%Z.