Section sec_map_modalop.
Variable A B: Type.
Proof using.
unfold and_tl; intuition.
Qed.
Proof using.
unfold and_tl; intuition.
Qed.
Proof using.
unfold or_tl; intuition.
Qed.
Proof using.
unfold or_tl; intuition.
Qed.
Proof using.
unfold impl_tl; intuition.
Qed.
Proof using.
unfold impl_tl; intuition.
Qed.
Proof using.
unfold not_tl; intuition.
Qed.
Proof using.
unfold not_tl; intuition.
Qed.
Proof using.
intros f P (x, s) nP; assumption.
Qed.
Proof using.
intros f P (x, s) nP; assumption.
Qed.
Proof using.
intros f P Q PQ [x s]; apply PQ.
Qed.
Proof using.
intros f P Q QP [x s]; apply QP.
Qed.
Proof using.
intros f P (x, (y, s)) nP; assumption.
Qed.
Proof using.
intros f P (x, (y, s)) nP; assumption.
Qed.
Proof using.
intros f P Q PQ. cofix cf.
intros (x, s) a. case (always_Cons a); intros a1 a2. constructor.
- apply PQ. assumption.
- rewrite map_Cons; simpl. apply cf; assumption.
Qed.

Lemma always_map_conv_ext :
forall (f: A->B) (P: infseq A->Prop) (Q: infseq B->Prop) (J : infseq A -> Prop),
(forall x s, J (Cons x s) -> J s) ->
(forall s, J s -> Q (map f s) -> P s) ->
forall s, J s -> always Q (map f s) -> always P s.