From Undecidability.L Require Export Util.L_facts.
From Undecidability.L.Tactics Require Export LClos_Eval.
From Undecidability.L.Tactics Require Import mixedTactics.
(* *** Reflexted closure calculus *)
(* This moduel provides definitions of an symbolic simplifier for reflected L-terms used in Lbeta *)
Open Scope LClos.
Inductive rTerm : Type :=
| rVar (x : nat) : rTerm
| rApp (s : rTerm) (t : rTerm) : rTerm
| rLam (s : rTerm)
| rConst (x : nat) : rTerm
| rRho (s : rTerm).
Coercion rApp : rTerm >-> Funclass.
Definition denoteTerm (phi : nat -> term) :rTerm->term :=
fix denoteTerm s :=
match s with
| rVar n => var n
| rApp s t=> app (denoteTerm s) (denoteTerm t)
| rLam s => lam (denoteTerm s)
| rConst n => phi n
| rRho s => rho (denoteTerm s)
end.
Definition Proc phi := forall (n:nat) , proc (phi n).
Definition rClosed phi s:= Proc phi /\ closed (denoteTerm phi s).
Definition rPow phi n s t :=
denoteTerm phi s >(n) denoteTerm phi t.
unfold rPow;tauto.
Qed.
Inductive rComp : Type :=
| rCompVar (x:nat)
| rCompApp (s : rComp) (t : rComp) : rComp
| rCompClos (s : rTerm) (A : list rComp) : rComp.
Coercion rCompApp : rComp >-> Funclass.
Definition denoteComp (phi : nat -> term) :rComp -> Comp:=
fix denoteComp s :=
match s with
| rCompVar x => CompVar x
| rCompApp s t => (denoteComp s) (denoteComp t)
| rCompClos s A => CompClos (denoteTerm phi s) (map denoteComp A)
end.
Fixpoint rSubstList (s:rTerm) (x:nat) (A: list rTerm): rTerm :=
match s with
| rVar n => if Dec ( n < x )then rVar n else nth (n-x) A (rVar n)
| rApp s t => (rSubstList s x A) (rSubstList t x A)
| rLam s => rLam (rSubstList s (S x) A)
| rRho s => rRho (rSubstList s (S x) A)
| rConst x => rConst x
end.
Fixpoint rDeClos (s:rComp) : rTerm :=
match s with
| rCompVar x => rVar x
| rCompApp s t => (rDeClos s) (rDeClos t)
| rCompClos s A => rSubstList s 0 (map rDeClos A)
end.
Definition rComp_ind_deep'
(P : rComp -> Prop)
(Pl : list rComp -> Prop)
(IHVar : forall x : nat, P (rCompVar x))
(IHApp : forall s : rComp, P s -> forall t : rComp, P t -> P (s t))
(IHClos : forall (s : rTerm) (A : list rComp),
Pl A -> P (rCompClos s A))
(IHNil : Pl nil)
(IHCons : forall (a:rComp) (A : list rComp),
P a -> Pl A -> Pl (a::A))
(x:rComp) : P x :=
(fix f c : P c:=
match c with
| rCompVar x => IHVar x
| rCompApp s t => IHApp s (f s) t (f t)
| rCompClos s A => IHClos s A
((fix g A : Pl A :=
match A with
[] => IHNil
| a::A => IHCons a A (f a) (g A)
end) A)
end) x
.
Definition rComp_ind_deep
(P : rComp -> Prop)
(IHVar : forall x : nat, P (rCompVar x))
(IHApp : forall s : rComp, P s -> forall t : rComp, P t -> P (s t))
(IHClos : forall (s : rTerm) (A : list rComp),
(forall a, a el A -> P a) -> P (rCompClos s A)) : forall x, P x.
Definition rValidComp phi s := Proc phi /\validComp (denoteComp phi s).
Definition rCompBeta s t :=
match s,t with
|rCompClos (rLam ls) A,rCompClos (rLam lt) B => Some (rCompClos ls (t::A))
|rCompClos (rLam ls) A,rCompClos (rConst x) B => Some (rCompClos ls (t::A))
|rCompClos (rLam ls) A,rCompClos (rRho lt) B => Some (rCompClos ls (t::A))
|_,_ => None
end.
Definition rCompAppCount :=
fun (j : nat) (u v : nat * rComp) => let (l, u0) := u in let (k, v0) := v in (j + (l + k), u0 v0).
Fixpoint rCompSeval' n (u : nat*rComp) : (nat *rComp)*bool:=
match n with
S n =>
match u with
| (l, rCompApp s t) =>
match rCompSeval' n (0,s),rCompSeval' n (0,t) with
(i, s',true),(j, t',true) =>
match rCompBeta s' t' with
Some u => rCompSeval' n ((S l)+(i+j),u)
| None => ((l+(i+j),s' t'),false)
end
| ((i,s'),_),((j,t'),_) => ((l+(i+j),s' t'),false)
end
| (l, rCompClos (rApp s t) A ) =>
rCompSeval' n (l, rCompApp (rCompClos s A) (rCompClos t A))
| (l , rCompClos (rVar x) A )=> (l,nth x A (rCompVar x),true)
| (l, rCompClos (rConst x) A )=> (u,true)
| (l, rCompVar x ) => (u,true)
| (l, rCompClos (rLam _) A) => (u,true)
| (l, rCompClos (rRho _) A) => (u,true)
end
| 0 => (u,true)
end.
Definition rCompSeval n u : (nat*rComp):=
(fst (rCompSeval' n u)).
Proof with simpl in *;try congruence;auto.
intros pp eq. destruct s... destruct s... destruct t... destruct s0; inv eq...
-constructor. apply pp.
-constructor. eexists. reflexivity.
Qed.
Functional Scheme rCompSeval'_ind := Induction for rCompSeval' Sort Prop.
Proof with (repeat inv_validComp;repeat (eassumption || constructor || intuition|| subst ; eauto using star || rewrite Nat.sub_diag in * || rewrite <- minus_n_O in *||cbn in * )).
intros. unfold rCompSeval.
pose (p:= (l,s)).
change (let (k, t) := fst (rCompSeval' n p) in k >= fst p /\denoteComp phi  (snd p) >[(k-(fst p))] denoteComp phi t).
generalize p. clear l s p. intros p.
functional induction (rCompSeval' n p); intros;cbn...
-rewrite e2,e5 in *...  eapply rCompBeta_sound in e8;try eauto. destruct (rCompSeval' _ (S _,_ ));destruct p... eapply (CPow_trans (t:= denoteComp phi (s' t')))...
-rewrite e2,e5 in *...  eapply (CPow_trans (t:= denoteComp phi (s' t')))...
-rewrite e2,e5 in *...  eapply (CPow_trans (t:= denoteComp phi (s' t')))...
-rewrite e2,e5 in *...  eapply (CPow_trans (t:= denoteComp phi (s' t')))...
-rewrite <- map_nth...
-repeat destruct (rCompSeval' _ _)... destruct p... eapply CPow_trans...
Qed.
Proof with repeat (congruence || subst || simpl in * || intuition ).
unfold rValidComp in *. intros vs vt eq. assert (pp:Proc phi)by (inv vs;auto). split;auto.  unfold rCompBeta in eq. destruct s... destruct s... destruct t... destruct s0...
-inv eq. inv H0; inv H2. constructor... rewrite map_length in *. now inv H7.
-inv eq. inv H0; inv H2. constructor...
+destruct (pp x) as [_ H']. inv H'. now rewrite H0.
+rewrite map_length in *. now inv H7.
-inv eq. inv H0; inv H2. constructor...
+rewrite map_length in *. now inv H7.
+rewrite map_length in *. now inv H7.
Qed.
Proof with repeat (eapply validCompApp ||apply validCompClos || congruence || subst || simpl in * || intuition).
intros P. unfold rCompSeval. revert s k. induction n; intros s k [? vs];(split;[auto|])... destruct s;try now  inv vs;cbn...
-inv vs. assert (IHn1 := IHn s1 0 ). assert (IHn2 := IHn s2 0).
unfold snd,fst in *. do 2 destruct ((rCompSeval' n (_,_)))... destruct p,p0... unfold rValidComp in *. destruct b,b0... destruct (rCompBeta r r0) eqn:eq;unfold rValidComp in *.
+apply IHn... eapply rCompBeta_rValidComp;eauto;  unfold rValidComp in *...
+idtac...
-unfold rValidComp in *. inv vs. destruct s;simpl...
+rewrite <- map_nth. apply H2. apply nth_In. now inv H4.
+apply IHn;auto. simpl in *. split;auto. inv H4. repeat constructor...
Qed.
intros pp. rewrite (denoteTerm_correct _ pp). simpl. rewrite rSubstList_correct;auto. simpl. now rewrite substList_nil.
Qed.
Proof with repeat (eauto || congruence || subst || simpl in * || intuition).
intros pp [? H]. unfold rValidComp in *. split;try tauto.  simpl. apply deClos_valComp in H. apply validComp_closed. now rewrite <- denoteTerm_correct.
Qed.
Proof with eauto.
intros pp cl. unfold rPow. rewrite rClosed_valid in *;auto. assert (cl': rValidComp phi (snd (rCompSeval n (0,rCompClos s [])))).
-apply rCompSeval_rValidComp;auto.
- destruct rCompSeval eqn:eq1. rewrite !expandDenote;auto.  specialize (rCompSeval_sound n (rCompClos s []) 0 pp);intros  H. rewrite eq1 in H.
destruct H as [_ H]. rewrite <- minus_n_O in H. rewrite <- rDeClos_reduce... apply deClos_correct... destruct cl...
Qed.
Fixpoint rClosed_decb' n u : bool:=
match u with
| rApp s t => andb (rClosed_decb' n s) (rClosed_decb' n t)
| rVar x => negb (leb n x)
| rConst x => true
| rLam s =>rClosed_decb' (S n) s
| rRho s =>rClosed_decb' (S n) s
end.
Definition rClosed_decb s:= rClosed_decb' 0 s.

Lemma rClosed_decb_correct phi s : Proc phi -> rClosed_decb s = true -> rClosed phi s.