Local Open Scope pred.
Hint Rewrite @sepcon_emp @emp_sepcon @TT_and @andp_TT
@exp_sepcon1 @exp_sepcon2
@exp_andp1 @exp_andp2
@sepcon_andp_prop @sepcon_andp_prop'
: normalize.
Definition pure {A}{JA: Join A}{PA: Perm_alg A}{SA: Sep_alg A}{agA: ageable A}{AgeA: Age_alg A}
(P: pred A) : Prop :=
P |-- emp.
Hint Resolve @pure_e : core.
Hint Resolve @pure_emp : core.
Hint Resolve @pure_existential : core.
Hint Rewrite @FF_sepcon @sepcon_FF : normalize.
Hint Rewrite @prop_true_andp using (solve [auto]) : normalize.

Lemma true_eq {A} `{ageable A}:  forall P: Prop, P -> (!! P) = (TT: pred A).