Fixpoint list_denote l : T :=
  match l with nil => b | x :: l' => g (f x) (list_denote l')
  end.Notation "'un'" := (@orp _).

Lemma listd_unfold_app_inter b l l' : listd f inter b (l ++ l') = (listd f inter TT l && listd f inter b l')%pred.