(* Condition variables *)
(*Definition _cond_t := 4%positive.*)
Definition tcond := tint.
(* Does this need to be anything special? *)
Definition cond_var {cs} sh v := @data_at_ cs sh tcond v.
(*+ Specification of each concurrent primitive *)

Lemma approx_eq_i':
forall (P Q : pred rmap) n,
(|> (P <=> Q))%pred n -> approx n P = approx n Q.