Definition superprecise {A}  {JA: Join A}{PA: Perm_alg A}{SA: Sep_alg A} (P: pred A) :=
   forall w1 w2, P w1 -> P w2 -> comparable w1 w2 -> w1=w2.

Lemma modus_ewand {A} {JA: Join A}{PA: Perm_alg A}{SA: Sep_alg A} : forall P Q, superprecise P -> P * (ewand P Q) |-- Q.