Definition get_val_equiv s s' : Prop :=
  forall k, get_val k s = get_val k s'.

Lemma poram_lift_change_post {X Y} (Pre Post Post' : state -> state -> Prop) {P : X -> Y -> Prop} (m : Poram X) (m' : Poram Y) : (forall s s', well_formed s -> well_formed s' -> Post s s' -> Post' s s') -> poram_lift2 Pre Post P m m' -> poram_lift2 Pre Post' P m m'.