Use a stack instead

mambo.agda

@@ -1,10 +1,14 @@
 {-# OPTIONS --no-import-sorts #-}
 open import Agda.Primitive renaming (Set to Type)
 open import Agda.Builtin.Nat
-open import Agda.Builtin.List
 
 data Bottom : Type where
 
+infixl 10 _,_
+data Stack (A : Type) : Type where
+  ∙ : Stack A
+  _,_ : Stack A → A → Stack A
+
 ¬ : Type → Type
 ¬ A = A → Bottom
 
@@ -58,14 +62,14 @@ X ⇔ Y = (X ⇒ Y) ∧ (Y ⇒ X)
 ◇ p = ∼ (□ (∼ p))
 
 infix 9 _∈_
-data _∈_ {A : Type} : A → List A → Type where
-  zero : (x : A) (xs : List A) → x ∈ (x ∷ xs)
-  succ : {y : A} (x : A) (xs : List A) → (x ∈ xs) → (x ∈ (y ∷ xs))
+data _∈_ {A : Type} : A → Stack A → Type where
+  zero : (x : A) (xs : Stack A) → x ∈ (xs , x)
+  succ : {y : A} (x : A) (xs : Stack A) → (x ∈ xs) → (x ∈ (xs , y))
 
 record M (W : Type) : Type₁ where
   field
     R : Rel W W
-    L : W → List Nat
+    L : W → Stack Nat
 
 infix 2 _,_⊩_
 _,_⊩_ : {W : Type} (Model : M W) (x : W) (p : Formula) → Type 
@@ -86,39 +90,37 @@ data R : Nat → Nat → Type where
 ExampleModel : M Nat
 ExampleModel .M.R = R
 
-ExampleModel .M.L 0 = 0 ∷ []
-ExampleModel .M.L 1 = 1 ∷ 2 ∷ []
-ExampleModel .M.L 2 = 0 ∷ 2 ∷ []
-ExampleModel .M.L _ = []
+ExampleModel .M.L 0 = ∙ , 0
+ExampleModel .M.L 1 = ∙ , 2 , 1
+ExampleModel .M.L 2 = ∙ , 2 , 0
+ExampleModel .M.L _ = ∙
 
 
 KSem : ExampleModel , 0 ⊩ □ (atom 1 ⇒ atom 2) ⇒ (□ atom 1 ⇒ □ atom 2)
-KSem x x₁ y zeroone = succ 2 (2 ∷ []) (zero 2 [])
-KSem x x₁ y zerotwo = succ 2 (2 ∷ []) (zero 2 [])
+KSem x x₁ y zeroone = succ 2 (∙ , 2) (zero 2 ∙)
+KSem x x₁ y zerotwo = succ 2 (∙ , 2) (zero 2 ∙)
 
 ExampleSem : ExampleModel , 0 ⊩ □ (atom 2)
-ExampleSem y zeroone = succ 2 (2 ∷ []) (zero 2 [])
-ExampleSem y zerotwo = succ 2 (2 ∷ []) (zero 2 [])
+ExampleSem y zeroone = succ 2 (∙ , 2) (zero 2 ∙)
+ExampleSem y zerotwo = succ 2 (∙ , 2) (zero 2 ∙)
 
 Example2Sem : ExampleModel , 0 ⊩ ◇ (atom 1)
-Example2Sem = pair 1 (λ _ → zero 1 (2 ∷ []))
+Example2Sem = pair 1 (λ _ → zero 1 (∙ , 2))
 
 Context : Type
-Context = List Formula
+Context = Stack Formula
 
 variable
   Γ Δ Γ' Δ' : Context
 
-infixl 10 _,_
-pattern _,_ Γ X = X ∷ Γ
 
 infix 9 _++_
-_++_ : {A : Type} → List A → List A → List A
-[] ++ ys = ys
-(x ∷ xs) ++ ys = x ∷ (xs ++ ys)
+_++_ : {A : Type} → Stack A → Stack A → Stack A
+xs ++ ∙ = xs
+xs ++ ys , y = (xs ++ ys) , y
 
 infix 8 _⊆_
-_⊆_ : {A : Type} → (Γ Γ' : List A) → Type
+_⊆_ : {A : Type} → (Γ Γ' : Stack A) → Type
 _⊆_ {A} Γ Γ' = ∀ {X} → X ∈ Γ → X ∈ Γ'
 
 infixr 2 _/_⊢_
@@ -135,18 +137,18 @@ data _/_⊢_ (Δ Γ : Context) : Formula → Type where
   ¬ᵢ : Δ / Γ , X ⊢ ⊥ → Δ / Γ ⊢ ∼ X
   ¬ₑ : Δ / Γ ⊢ ∼ X → Δ / Γ ⊢ X → Δ / Γ ⊢ ⊥
   ⊥ₑ : Δ / Γ ⊢ ⊥ → Δ / Γ ⊢ X
-  □ᵢ : [] / Δ ⊢ X → Δ / Γ ⊢ □ X
+  □ᵢ : ∙ / Δ ⊢ X → Δ / Γ ⊢ □ X
   □ₑ : Δ / Γ ⊢ □ X → (Δ , X) / Γ ⊢ Y → Δ / Γ ⊢ Y
   -- TODO: Maybe make it KT45
 
-inSwap : {A : Type} {X Y Z : A} (Γ Γ' : List A) → Z ∈ (Γ' ++ Γ , X , Y) → Z ∈ (Γ' ++ Γ , Y , X)
-inSwap Γ [] (zero x xs) = succ x (Γ , x) (zero x Γ)
-inSwap Γ [] (succ x xs (zero x₁ xs₁)) = zero x (Γ , _)
-inSwap Γ [] (succ x xs (succ x₁ xs₁ x₂)) = succ x (Γ , _) (succ x Γ x₂)
-inSwap Γ (Γ' , x₁) (zero x xs) = zero x₁ (Γ' ++ Γ , _ , _)
-inSwap Γ (Γ' , x₁) (succ x xs x₂) = succ x (Γ' ++ Γ , _ , _) (inSwap Γ Γ' x₂)
+inSwap : {A : Type} {X Y Z : A} (Γ Γ' : Stack A) → Z ∈ (Γ , X , Y ++ Γ') → Z ∈ (Γ , Y , X ++ Γ')
+inSwap Γ ∙ (zero x xs) = succ x (Γ , x) (zero x Γ)
+inSwap Γ ∙ (succ x xs (zero x₁ xs₁)) = zero x (Γ , _)
+inSwap Γ ∙ (succ x xs (succ x₁ xs₁ x₂)) = succ x (Γ , _) (succ x Γ x₂)
+inSwap Γ (Γ' , x₁) (zero x xs) = zero x₁ (Γ , _ , _ ++ Γ')
+inSwap Γ (Γ' , x₁) (succ x xs x₂) = succ x (Γ , _ , _ ++ Γ') (inSwap Γ Γ' x₂)
 
-exchange : (Γ' : Context) → Δ / Γ' ++ (Γ , A , B)  ⊢ C → Δ / Γ' ++ (Γ , B , A) ⊢ C
+exchange : (Γ' : Context) → Δ / (Γ , A , B) ++ Γ'  ⊢ C → Δ / (Γ , B , A) ++ Γ' ⊢ C
 exchange Γ' (var x) = var (inSwap _ Γ' x)
 exchange Γ' (mp x x₁) = mp (exchange Γ' x) (exchange Γ' x₁)
 exchange Γ' (∧ᵢ x x₁) = ∧ᵢ (exchange Γ' x) (exchange Γ' x₁)
@@ -162,7 +164,7 @@ exchange Γ' (⊥ₑ x) = ⊥ₑ (exchange Γ' x)
 exchange Γ' (□ᵢ x) = □ᵢ x
 exchange Γ' (□ₑ x x₁) = □ₑ (exchange Γ' x) (exchange Γ' x₁)
 
-exchange-modal : (Δ' : Context) →  Δ' ++ Δ , A , B  / Γ ⊢ C → Δ' ++ Δ , B , A / Γ ⊢ C
+exchange-modal : (Δ' : Context) →  Δ , A , B  ++ Δ' / Γ ⊢ C → Δ , B , A ++ Δ' / Γ ⊢ C
 exchange-modal Δ' (var x) = var x
 exchange-modal Δ' (mp x x₁) = mp (exchange-modal Δ' x) (exchange-modal Δ' x₁)
 exchange-modal Δ' (∧ᵢ x x₁) = ∧ᵢ (exchange-modal Δ' x) (exchange-modal Δ' x₁)
@@ -178,7 +180,7 @@ exchange-modal Δ' (⊥ₑ x) = ⊥ₑ (exchange-modal Δ' x)
 exchange-modal Δ' (□ᵢ x) = □ᵢ (exchange Δ' x)
 exchange-modal Δ' (□ₑ x x₁) = □ₑ (exchange-modal Δ' x) (exchange-modal (Δ' , _) x₁)
 
-inBoth : {A : Type} {Γ Γ' : List A} {X : A} → Γ ⊆ Γ' → (Γ , X) ⊆ (Γ' , X)
+inBoth : {A : Type} {Γ Γ' : Stack A} {X : A} → Γ ⊆ Γ' → (Γ , X) ⊆ (Γ' , X)
 inBoth {A} {Γ} {Γ'} {X} x {X₁} (zero x₁ xs) = zero X Γ'
 inBoth {A} {Γ} {Γ'} {X} x {X₁} (succ x₁ xs x₂) = succ X₁ Γ' (x x₂)
 
@@ -214,21 +216,49 @@ weak-modal (⊥ₑ x) x₁ = ⊥ₑ (weak-modal x x₁)
 weak-modal (□ᵢ x) x₁ = □ᵢ (weak x x₁)
 weak-modal (□ₑ x x₂) x₁ = □ₑ (weak-modal x x₁) (weak-modal x₂ (inBoth x₁))
 
-cut : (Γ' : Context) → Δ / Γ ⊢ A → Δ / Γ' ++ (Γ , A) ⊢ B → Δ / Γ' ++ Γ ⊢ B
-cut Γ' x x₁ = {!!}
+cut : (Γ' : Context) → Δ / Γ ⊢ A → Δ / (Γ , A) ++ Γ' ⊢ B → Δ / Γ ++ Γ' ⊢ B
+cut ∙ x (var x₁) = mp (⇒ᵢ (var x₁)) x
+cut (Γ' , x₂) x (var (zero x₁ xs)) = var (zero x₂ (_ ++ Γ'))
+cut (Γ' , x₂) x (var (succ _ xs x₃)) = weak (cut Γ' x (var x₃)) λ {X} → succ X (_ ++ Γ')
+cut Γ' x (mp x₁ x₂) = mp (cut Γ' x x₁) (cut Γ' x x₂)
+cut Γ' x (∧ᵢ x₁ x₂) = ∧ᵢ (cut Γ' x x₁) (cut Γ' x x₂)
+cut Γ' x (∧ₑ₁ x₁) = ∧ₑ₁ (cut Γ' x x₁)
+cut Γ' x (∧ₑ₂ x₁) = ∧ₑ₂ (cut Γ' x x₁)
+cut Γ' x (∨ᵢ₁ x₁) = ∨ᵢ₁ (cut Γ' x x₁)
+cut Γ' x (∨ᵢ₂ x₁) = ∨ᵢ₂ (cut Γ' x x₁)
+cut Γ' x (∨ₑ x₁ x₂ x₃) = ∨ₑ (cut Γ' x x₁) (cut (Γ' , _) x x₂) (cut (Γ' , _ ) x x₃)
+cut Γ' x (⇒ᵢ x₁) = ⇒ᵢ (cut (Γ' , _) x x₁)
+cut Γ' x (¬ᵢ x₁) = ¬ᵢ (cut (Γ' , _) x x₁)
+cut Γ' x (¬ₑ x₁ x₂) = ¬ₑ (cut Γ' x x₁) (cut Γ' x x₂)
+cut Γ' x (⊥ₑ x₁) = ⊥ₑ (cut Γ' x x₁)
+cut Γ' x (□ᵢ x₁) = □ᵢ x₁
+cut Γ' x (□ₑ x₁ x₂) = □ₑ (cut Γ' x x₁) (cut Γ' (weak-modal x (λ {X = X₁} → succ X₁ _)) x₂)
 
-cut-modal : Δ / Γ ⊢ A → Δ' ++ (Δ , A) / Γ ⊢ B → Δ' ++ Δ / Γ ⊢ B
-cut-modal = {!!}
+cut-modal : (Δ' : Context) → ∙ / Δ ⊢ A → (Δ , A) ++ Δ' / Γ ⊢ B → Δ ++ Δ' / Γ ⊢ B
+cut-modal Δ' x (var x₁) = var x₁
+cut-modal Δ' x (mp x₁ x₂) = mp (cut-modal Δ' x x₁) (cut-modal Δ' x x₂)
+cut-modal Δ' x (∧ᵢ x₁ x₂) = ∧ᵢ (cut-modal Δ' x x₁) (cut-modal Δ' x x₂)
+cut-modal Δ' x (∧ₑ₁ x₁) = ∧ₑ₁ (cut-modal Δ' x x₁)
+cut-modal Δ' x (∧ₑ₂ x₁) = ∧ₑ₂ (cut-modal Δ' x x₁)
+cut-modal Δ' x (∨ᵢ₁ x₁) = ∨ᵢ₁ (cut-modal Δ' x x₁)
+cut-modal Δ' x (∨ᵢ₂ x₁) = ∨ᵢ₂ (cut-modal Δ' x x₁)
+cut-modal Δ' x (∨ₑ x₁ x₂ x₃) = ∨ₑ (cut-modal Δ' x x₁) (cut-modal Δ' x x₂) (cut-modal Δ' x x₃)
+cut-modal Δ' x (⇒ᵢ x₁) = ⇒ᵢ (cut-modal Δ' x x₁)
+cut-modal Δ' x (¬ᵢ x₁) = ¬ᵢ (cut-modal Δ' x x₁)
+cut-modal Δ' x (¬ₑ x₁ x₂) = ¬ₑ (cut-modal Δ' x x₁) (cut-modal Δ' x x₂)
+cut-modal Δ' x (⊥ₑ x₁) = ⊥ₑ (cut-modal Δ' x x₁)
+cut-modal Δ' x (□ᵢ x₁) = □ᵢ (cut Δ' x x₁)
+cut-modal Δ' x (□ₑ x₁ x₂) = □ₑ (cut-modal Δ' x x₁) (cut-modal (Δ' , _) x x₂)
 
-KSym : [] / [] ⊢ □ (X ⇒ Y) ⇒ (□ X ⇒ □ Y)
-KSym {X} {Y} = ⇒ᵢ (⇒ᵢ (□ₑ (var (zero (□ X) ([] , (□ (X ⇒ Y)))))
-                      (□ₑ (var (succ (□(X ⇒ Y)) ([] , (□ (X ⇒ Y))) (zero (□ (X ⇒ Y)) [])))
+KSym : ∙ / ∙ ⊢ □ (X ⇒ Y) ⇒ (□ X ⇒ □ Y)
+KSym {X} {Y} = ⇒ᵢ (⇒ᵢ (□ₑ (var (zero (□ X) (∙ , (□ (X ⇒ Y)))))
+                      (□ₑ (var (succ (□(X ⇒ Y)) (∙ , (□ (X ⇒ Y))) (zero (□ (X ⇒ Y)) ∙)))
                       (□ᵢ (mp
-                        (var (zero (X ⇒ Y) ([] , X)))
-                        (var (succ X ([] , X) (zero X []))))))))
+                        (var (zero (X ⇒ Y) (∙ , X)))
+                        (var (succ X (∙ , X) (zero X ∙))))))))
 
-MTSym : [] / [] ⊢ (A ⇒ B) ⇒ ∼ B ⇒ ∼ A
-MTSym {A} {B} = ⇒ᵢ (⇒ᵢ (¬ᵢ (¬ₑ (var (succ (∼ B) ([] , (A ⇒ B) , (∼ B)) (zero (∼ B) ([] , (A ⇒ B))))) (mp (var (succ (A ⇒ B) ([] , (A ⇒ B) , (∼ B)) (succ (A ⇒ B) ([] , (A ⇒ B)) (zero (A ⇒ B) [])))) (var (zero A ([] , (A ⇒ B) , (∼ B))))))))
+MTSym : ∙ / ∙ ⊢ (A ⇒ B) ⇒ ∼ B ⇒ ∼ A
+MTSym {A} {B} = ⇒ᵢ (⇒ᵢ (¬ᵢ (¬ₑ (var (succ (∼ B) (∙ , (A ⇒ B) , (∼ B)) (zero (∼ B) (∙ , (A ⇒ B))))) (mp (var (succ (A ⇒ B) (∙ , (A ⇒ B) , (∼ B)) (succ (A ⇒ B) (∙ , (A ⇒ B)) (zero (A ⇒ B) ∙)))) (var (zero A (∙ , (A ⇒ B) , (∼ B))))))))
 
 DedSym : Δ / Γ ⊢ A ⇒ B → Δ / Γ , A ⊢ B
 DedSym {Δ} {Γ} {A} {B} (var x) = mp (var (succ (A ⇒ B) Γ x)) (var (zero A Γ))
@@ -243,15 +273,15 @@ DedSym {Δ} {Γ} {A} {B} (□ₑ x x₁) = mp (weak (□ₑ x x₁) (λ {X = X
 DedSymInv : Δ / Γ , A ⊢ B → Δ / Γ ⊢ A ⇒ B
 DedSymInv {Δ} {Γ} {A} {B} x = ⇒ᵢ x
 
-ExampleSyn : [] / [] ⊢ □ X ⇒ □ (Y ⇒ X)
-ExampleSyn {X} {Y} = ⇒ᵢ (□ₑ (var (zero (□ X) [])) (□ᵢ (⇒ᵢ (var (succ X ([] , X) (zero X []))))))
+ExampleSyn : ∙ / ∙ ⊢ □ X ⇒ □ (Y ⇒ X)
+ExampleSyn {X} {Y} = ⇒ᵢ (□ₑ (var (zero (□ X) ∙)) (□ᵢ (⇒ᵢ (var (succ X (∙ , X) (zero X ∙))))))
 
-ExampleSyn2 : [] / [] ⊢ □(A ∧ B) ⇒ (□ A ∧ □ B)
-ExampleSyn2 {A} {B} = ⇒ᵢ (∧ᵢ (□ₑ (var (zero (□ (A ∧ B)) [])) (□ᵢ (∧ₑ₁ (var (zero (A ∧ B) []))))) (□ₑ (var (zero (□ (A ∧ B)) [])) (□ᵢ (∧ₑ₂ (var (zero (A ∧ B) []))))))
+ExampleSyn2 : ∙ / ∙ ⊢ □(A ∧ B) ⇒ (□ A ∧ □ B)
+ExampleSyn2 {A} {B} = ⇒ᵢ (∧ᵢ (□ₑ (var (zero (□ (A ∧ B)) ∙)) (□ᵢ (∧ₑ₁ (var (zero (A ∧ B) ∙))))) (□ₑ (var (zero (□ (A ∧ B)) ∙)) (□ᵢ (∧ₑ₂ (var (zero (A ∧ B) ∙))))))
 
-ExampleSyn3 : [] / [] ⊢ (□ A ∧ □ B) ⇒ □(A ∧ B)
-ExampleSyn3 {A} {B} = ⇒ᵢ (□ₑ (∧ₑ₁ (var (zero ((□ A) ∧ (□ B)) []))) (□ₑ (∧ₑ₂ (var (zero ((□ A) ∧ (□ B)) []))) (□ᵢ (∧ᵢ (var (succ A ([] , A) (zero A []))) (var (zero B ([] , A)))))))
+ExampleSyn3 : ∙ / ∙ ⊢ (□ A ∧ □ B) ⇒ □(A ∧ B)
+ExampleSyn3 {A} {B} = ⇒ᵢ (□ₑ (∧ₑ₁ (var (zero ((□ A) ∧ (□ B)) ∙))) (□ₑ (∧ₑ₂ (var (zero ((□ A) ∧ (□ B)) ∙))) (□ᵢ (∧ᵢ (var (succ A (∙ , A) (zero A ∙))) (var (zero B (∙ , A)))))))
 
-ExampleSyn4 : [] / [] ⊢ □ (A ⇒ B) ⇒ (◇ A ⇒ ◇ B)
-ExampleSyn4 {A} {B} = ⇒ᵢ (⇒ᵢ (¬ᵢ (□ₑ (var (zero (□ (∼ B)) ([] , (□ (A ⇒ B)) , (◇ A)))) (□ₑ (var (succ (□ (A ⇒ B)) ([] , (□ (A ⇒ B)) , (◇ A)) (succ (□ (A ⇒ B)) ([] , (□ (A ⇒ B))) (zero (□ (A ⇒ B)) [])))) (¬ₑ (var (succ (∼ (□ (∼ A))) ([] , (□ (A ⇒ B)) , (◇ A))
-                                                                                                                                                                                                                      (zero (∼ (□ (∼ A))) ([] , (□ (A ⇒ B)))))) (□ᵢ (¬ᵢ (¬ₑ (var (succ ( ∼ B) ([] , (∼ B) , (A ⇒ B)) (succ (∼ B) ([] , (∼ B)) (zero (∼ B) [])))) (mp (var (succ (A ⇒ B) ([] , (∼ B) , (A ⇒ B)) (zero (A ⇒ B) ([] , (∼ B))))) (var (zero A ([] , (∼ B) , (A ⇒ B)))))))))))))
+ExampleSyn4 : ∙ / ∙ ⊢ □ (A ⇒ B) ⇒ (◇ A ⇒ ◇ B)
+ExampleSyn4 {A} {B} = ⇒ᵢ (⇒ᵢ (¬ᵢ (□ₑ (var (zero (□ (∼ B)) (∙ , (□ (A ⇒ B)) , (◇ A)))) (□ₑ (var (succ (□ (A ⇒ B)) (∙ , (□ (A ⇒ B)) , (◇ A)) (succ (□ (A ⇒ B)) (∙ , (□ (A ⇒ B))) (zero (□ (A ⇒ B)) ∙)))) (¬ₑ (var (succ (∼ (□ (∼ A))) (∙ , (□ (A ⇒ B)) , (◇ A))
+                                                                                                                                                                                                                      (zero (∼ (□ (∼ A))) (∙ , (□ (A ⇒ B)))))) (□ᵢ (¬ᵢ (¬ₑ (var (succ ( ∼ B) (∙ , (∼ B) , (A ⇒ B)) (succ (∼ B) (∙ , (∼ B)) (zero (∼ B) ∙)))) (mp (var (succ (A ⇒ B) (∙ , (∼ B) , (A ⇒ B)) (zero (A ⇒ B) (∙ , (∼ B))))) (var (zero A (∙ , (∼ B) , (A ⇒ B)))))))))))))