tinied up everything in enclosed files, with normalized notation

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2023-05-25 12:02:36 +02:00
parent ef0d5a51d7
commit d1a0177d2c
5 changed files with 373 additions and 1 deletions
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*.agdai
*~
\#*\#
.\#*
*.kate-swp
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{-# OPTIONS --prop #-}
module Prop where
-- ⊥ is a data with no constructor
-- ⊤ is a record with one always-available constructor
data ⊥ : Prop where
record ⊤ : Prop where
constructor tt
data _∨_ : Prop → Prop → Prop where
inj₁ : {P Q : Prop} → P → P ∨ Q
inj₂ : {P Q : Prop} → Q → P ∨ Q
record _∧_ (P Q : Prop) : Prop where
constructor ⟨_,_⟩
field
p : P
q : Q
infixr 10 _∧_
infixr 11 _∨_
-- ∧ elimination
proj₁ : {P Q : Prop} → P ∧ Q → P
proj₁ pq = _∧_.p pq
proj₂ : {P Q : Prop} → P ∧ Q → Q
proj₂ pq = _∧_.q pq
-- ¬ is a shorthand for « → ⊥ »
¬ : Prop → Prop
¬ P = P → ⊥
-- ⊥ elimination
case⊥ : {P : Prop} → ⊥ → P
case⊥ ()
-- ∨ elimination
dis : {P Q S : Prop} → (P ∨ Q) → (P → S) → (Q → S) → S
dis (inj₁ p) ps qs = ps p
dis (inj₂ q) ps qs = qs q
-- ⇔ shorthand
_⇔_ : Prop → Prop → Prop
P ⇔ Q = (P → Q) ∧ (Q → P)
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{-# OPTIONS --prop #-}
module PropUtil where
-- ⊥ is a data with no constructor
-- ⊤ is a record with one always-available constructor
data ⊥ : Prop where
record ⊤ : Prop where
constructor tt
data _∨_ : Prop → Prop → Prop where
inj₁ : {P Q : Prop} → P → P ∨ Q
inj₂ : {P Q : Prop} → Q → P ∨ Q
record _∧_ (P Q : Prop) : Prop where
constructor ⟨_,_⟩
field
p : P
q : Q
infixr 10 _∧_
infixr 11 _∨_
-- ∧ elimination
proj₁ : {P Q : Prop} → P ∧ Q → P
proj₁ pq = _∧_.p pq
proj₂ : {P Q : Prop} → P ∧ Q → Q
proj₂ pq = _∧_.q pq
-- ∨ elimination
dis : {P Q S : Prop} → (P ∨ Q) → (P → S) → (Q → S) → S
dis (inj₁ p) ps qs = ps p
dis (inj₂ q) ps qs = qs q
-- ¬ is a shorthand for « → ⊥ »
¬ : Prop → Prop
¬ P = P → ⊥
-- ⊥ elimination
case⊥ : {P : Prop} → ⊥ → P
case⊥ ()
-- ⇔ shorthand
_⇔_ : Prop → Prop → Prop
P ⇔ Q = (P → Q) ∧ (Q → P)
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{-# OPTIONS --prop #-}
module PropositionalKripke (PV : Set) where
open import PropUtil
open import PropositionalLogic PV
private
variable
x : PV
y : PV
F : Form
G : Form
Γ : Con
Γ' : Con
Η : Con
Η' : Con
record Kripke : Set₁ where
field
Worlds : Set₀
_≤_ : Worlds → Worlds → Prop
refl≤ : {w : Worlds} → w ≤ w
tran≤ : {a b c : Worlds} → a ≤ b → b ≤ c → a ≤ c
_⊩_ : Worlds → PV → Prop
mon⊩ : {a b : Worlds} → a ≤ b → {p : PV} → a ⊩ p → b ⊩ p
private
variable
w : Worlds
w' : Worlds
w₁ : Worlds
w₂ : Worlds
w₃ : Worlds
{- Extending ⊩ to Formulas and Contexts -}
_⊩ᶠ_ : Worlds → Form → Prop
w ⊩ᶠ Var x = w ⊩ x
w ⊩ᶠ (fp ⇒ fq) = {w' : Worlds} → w ≤ w' → w' ⊩ᶠ fp → w' ⊩ᶠ fq
_⊩ᶜ_ : Worlds → Con → Prop
w ⊩ᶜ [] = ⊤
w ⊩ᶜ (p ∷ c) = (w ⊩ᶠ p) ∧ (w ⊩ᶜ c)
-- The extensions are monotonous
mon⊩ᶠ : w ≤ w' → w ⊩ᶠ F → w' ⊩ᶠ F
mon⊩ᶠ {F = Var x} ww' wF = mon⊩ ww' wF
mon⊩ᶠ {F = F ⇒ G} ww' wF w'w'' w''F = wF (tran≤ ww' w'w'') w''F
mon⊩ᶜ : w ≤ w' → w ⊩ᶜ Γ → w' ⊩ᶜ Γ
mon⊩ᶜ {Γ = []} ww' wΓ = wΓ
mon⊩ᶜ {Γ = F ∷ Γ} ww' wΓ = ⟨ mon⊩ᶠ {F = F} ww' (proj₁ wΓ) , mon⊩ᶜ ww' (proj₂ wΓ) ⟩
{- General operator matching the shape of ⊢ -}
_⊫_ : Con → Form → Prop
Γ ⊫ F = {w : Worlds} → w ⊩ᶜ Γ → w ⊩ᶠ F
{- Soundness -}
⟦_⟧ : Γ ⊢ F → Γ ⊫ F
⟦ zero ⟧ = proj₁
⟦ next p ⟧ = λ x → ⟦ p ⟧ (proj₂ x)
⟦ lam p ⟧ = λ wΓ w≤ w'A → ⟦ p ⟧ ⟨ w'A , mon⊩ᶜ w≤ wΓ ⟩
⟦ app p p₁ ⟧ wΓ = ⟦ p ⟧ wΓ refl≤ (⟦ p₁ ⟧ wΓ)
{- Universal Kripke -}
module UniversalKripke where
Worlds = Con
_≤_ : Con → Con → Prop
Γ ≤ Η = Η ⊢⁺ Γ
_⊩_ : Con → PV → Prop
Γ ⊩ x = Γ ⊢ Var x
refl≤ = refl⊢⁺
-- Proving transitivity
halftran≤ : {Γ Γ' : Con} → {F : Form} → Γ ⊢⁺ Γ' → Γ' ⊢ F → Γ ⊢ F
halftran≤ h⁺ zero = proj₁ h⁺
halftran≤ h⁺ (next h) = halftran≤ (proj₂ h⁺) h
halftran≤ h⁺ (lam h) = lam (halftran≤ ⟨ zero , addhyp⊢⁺ h⁺ ⟩ h)
halftran≤ h⁺ (app h h') = app (halftran≤ h⁺ h) (halftran≤ h⁺ h')
tran≤ : {Γ Γ' Γ'' : Con} → Γ ≤ Γ' → Γ' ≤ Γ'' → Γ ≤ Γ''
tran≤ {[]} h h' = tt
tran≤ {x ∷ Γ} h h' = ⟨ halftran≤ h' (proj₁ h) , tran≤ (proj₂ h) h' ⟩
mon⊩ : {w w' : Con} → w ≤ w' → {x : PV} → w ⊩ x → w' ⊩ x
mon⊩ h h' = halftran≤ h h'
UK : Kripke
UK = record {UniversalKripke}
module CompletenessProof where
open Kripke UK
open UniversalKripke using (halftran≤)
⊩ᶠ→⊢ : {F : Form} → {Γ : Con} → Γ ⊩ᶠ F → Γ ⊢ F
⊢→⊩ᶠ : {F : Form} → {Γ : Con} → Γ ⊢ F → Γ ⊩ᶠ F
⊢→⊩ᶠ {Var x} h = h
⊢→⊩ᶠ {F ⇒ F₁} h {Γ'} iq hF = ⊢→⊩ᶠ {F₁} (app {Γ'} {F} {F₁} (lam (app (halftran≤ (addhyp⊢⁺ iq) h) zero)) (⊩ᶠ→⊢ hF))
⊩ᶠ→⊢ {Var x} h = h
⊩ᶠ→⊢ {F ⇒ F₁} {Γ} h = lam (⊩ᶠ→⊢ (h (addhyp⊢⁺ refl⊢⁺) (⊢→⊩ᶠ {F} {F ∷ Γ} zero)))
completeness : {F : Form} → [] ⊫ F → [] ⊢ F
completeness {F} ⊫F = ⊩ᶠ→⊢ (⊫F tt)
{- Normalization -}
norm : [] ⊢ F → [] ⊢ F
norm x = completeness (⟦ x ⟧)
-- norm is identity ?!
idnorm : norm x ≡ x
idnorm = ?
-- autonorm : (P₁ P₂ : Prop) → (x₁ : P₁) → (norm x₁ : P₂) → P₁ ≡⊢ P₂
-- βηnorm : (P₁ P₂ : Prop) → (x₁ : P₁) → (norm x₁ : P₂) → (x₂ : P₂) → norm x₁ ≡ x₂ → P₁ ≡⊢ P₂
-- autonorm P = {!!}
--βηnorm P₁ P₂ = ?
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{-# OPTIONS --prop #-}
module PropositionalLogic (PV : Set) where
open import PropUtil
open import Data.List using (List; _∷_; []) public
data Form : Set where
Var : PV → Form
_⇒_ : Form → Form → Form
infixr 8 _⇒_
data _≡_ : {A : Set} → A → A → Prop where
refl : {A : Set} → {x : A} → x ≡ x
{- Contexts -}
Con = List Form
private
variable
A : Form
A' : Form
B : Form
B' : Form
C : Form
Γ : Con
Γ' : Con
-- Definition of subcontexts (directly included)
-- Similar definition : {Γ' : Con} → Γ ⊆ Γ' ++ Γ
private
data _⊆_ : Con → Con → Prop where
zero⊆ : Γ ⊆ Γ
next⊆ : Γ ⊆ Γ' → Γ ⊆ (A ∷ Γ')
retro⊆ : {Γ Γ' : Con} → {A : Form} → (A ∷ Γ) ⊆ Γ' → Γ ⊆ Γ'
retro⊆ {Γ' = []} () -- Impossible to have «A∷Γ ⊆ []»
retro⊆ {Γ' = x ∷ Γ'} zero⊆ = next⊆ zero⊆
retro⊆ {Γ' = x ∷ Γ'} (next⊆ h) = next⊆ (retro⊆ h)
data _⊢_ : Con → Form → Prop where
zero : (A ∷ Γ) ⊢ A
next : Γ ⊢ A → (B ∷ Γ) ⊢ A
lam : (A ∷ Γ) ⊢ B → Γ ⊢ (A ⇒ B)
app : Γ ⊢ (A ⇒ B) → Γ ⊢ A → Γ ⊢ B
infix 5 _⊢_
-- Equality of derivation
infix 2 _≡⊢_
data _≡⊢_ : Prop → Prop → Prop where
refl : Γ ⊢ A ≡⊢ Γ ⊢ A
{-zero≡⊢ : (A ∷ Γ) ⊢ A ≡⊢ (A' ∷ Γ') ⊢ A'
next≡⊢ : Γ ⊢ A ≡⊢ Γ' ⊢ A' → (B ∷ Γ) ⊢ A ≡⊢ (B ∷ Γ') ⊢ A'
lam≡⊢ : (A ∷ Γ) ⊢ B ≡⊢ (A' ∷ Γ') ⊢ B' → Γ ⊢ (A ⇒ B) ≡⊢ Γ' ⊢ (A' ⇒ B')
app≡⊢ : Γ ⊢ (A ⇒ B) ≡⊢ Γ' ⊢ (A' ⇒ B') → Γ ⊢ A ≡⊢ Γ' ⊢ A' → Γ ⊢ B ≡⊢ Γ' ⊢ B'
-}
{-
-- Reflexivity of equality
refl≡⊢ : {Γ : Con} → {A : Form} → Γ ⊢ A ≡⊢ Γ ⊢ A
refl≡⊢ = {!!}
-- Symmetry of equality
sym≡⊢ : {Γ Γ' : Con} → {A A' : Form} → Γ ⊢ A ≡⊢ Γ' ⊢ A' → Γ' ⊢ A' ≡⊢ Γ ⊢ A
sym≡⊢ = {!!}
-- Transitivity of equality
tran≡⊢ : {Γ Γ' Γ'' : Con} → {A A' A'' : Form} → Γ ⊢ A ≡⊢ Γ' ⊢ A' → Γ' ⊢ A' ≡⊢ Γ'' ⊢ A'' → Γ ⊢ A ≡⊢ Γ'' ⊢ A''
tran≡⊢ = {!!}
-}
-- Extension of ⊢ to contexts
_⊢⁺_ : Con → Con → Prop
Γ ⊢⁺ [] = ⊤
Γ ⊢⁺ (F ∷ Γ') = (Γ ⊢ F) ∧ (Γ ⊢⁺ Γ')
infix 5 _⊢⁺_
-- This relation is reflexive
private -- Lemma showing that the relation respects ⊆
mon⊆≤ : Γ' ⊆ Γ → Γ ⊢⁺ Γ'
mon⊆≤ {[]} sub = tt
mon⊆≤ {x ∷ Γ} zero⊆ = ⟨ zero , mon⊆≤ (next⊆ zero⊆) ⟩
mon⊆≤ {x ∷ Γ} (next⊆ sub) = ⟨ (next (proj₁ (mon⊆≤ sub)) ) , mon⊆≤ (next⊆ (retro⊆ sub)) ⟩
refl⊢⁺ : Γ ⊢⁺ Γ
refl⊢⁺ {[]} = tt
refl⊢⁺ {x ∷ Γ} = ⟨ zero , mon⊆≤ (next⊆ zero⊆) ⟩
-- A useful lemma, that we can add hypotheses
addhyp⊢⁺ : Γ ⊢⁺ Γ' → (A ∷ Γ) ⊢⁺ Γ'
addhyp⊢⁺ {Γ' = []} h = tt
addhyp⊢⁺ {Γ' = A ∷ Γ'} h = ⟨ next (proj₁ h) , addhyp⊢⁺ (proj₂ h) ⟩
{--- Simple translation with in an Environment ---}
Env = PV → Prop
⟦_⟧ᶠ : Form → Env → Prop
⟦ Var x ⟧ᶠ ρ = ρ x
⟦ A ⇒ B ⟧ᶠ ρ = (⟦ A ⟧ᶠ ρ) → (⟦ B ⟧ᶠ ρ)
⟦_⟧ᶜ : Con → Env → Prop
⟦ [] ⟧ᶜ ρ = ⊤
⟦ A ∷ Γ ⟧ᶜ ρ = (⟦ A ⟧ᶠ ρ) ∧ (⟦ Γ ⟧ᶜ ρ)
⟦_⟧ᵈ : Γ ⊢ A → {ρ : Env} → ⟦ Γ ⟧ᶜ ρ → ⟦ A ⟧ᶠ ρ
⟦ zero ⟧ᵈ p = proj₁ p
⟦ next th ⟧ᵈ p = ⟦ th ⟧ᵈ (proj₂ p)
⟦ lam th ⟧ᵈ = λ pₐ p₀ → ⟦ th ⟧ᵈ ⟨ p₀ , pₐ ⟩
⟦ app th₁ th₂ ⟧ᵈ = λ p → ⟦ th₁ ⟧ᵈ p (⟦ th₂ ⟧ᵈ p)
{--- Combinatory Logic ---}
data ⊢sk : Form → Prop where
SS : ⊢sk ((A ⇒ B ⇒ C) ⇒ (A ⇒ B) ⇒ A ⇒ C)
KK : ⊢sk (A ⇒ B ⇒ A)
app : ⊢sk (A ⇒ B) → ⊢sk A → ⊢sk B
data _⊢skC_ : Con → Form → Prop where
zero : (A ∷ Γ) ⊢skC A
next : Γ ⊢skC A → (B ∷ Γ) ⊢skC A
SS : Γ ⊢skC ((A ⇒ B ⇒ C) ⇒ (A ⇒ B) ⇒ A ⇒ C)
KK : Γ ⊢skC (A ⇒ B ⇒ A)
app : Γ ⊢skC (A ⇒ B) → Γ ⊢skC A → Γ ⊢skC B
-- combinatory gives the same proofs as classic
⊢⇔⊢sk : ([] ⊢ A) ⇔ ⊢sk A
⊢sk→⊢ : ⊢sk A → ([] ⊢ A)
⊢sk→⊢ SS = lam (lam (lam ( app (app (next (next zero)) zero) (app (next zero) zero))))
⊢sk→⊢ KK = lam (lam (next zero))
⊢sk→⊢ (app x x₁) = app (⊢sk→⊢ x) (⊢sk→⊢ x₁)
skC→sk : [] ⊢skC A → ⊢sk A
skC→sk SS = SS
skC→sk KK = KK
skC→sk (app d e) = app (skC→sk d) (skC→sk e)
lam-sk : (A ∷ Γ) ⊢skC B → Γ ⊢skC (A ⇒ B)
lam-sk-zero : Γ ⊢skC (A ⇒ A)
lam-sk-zero {A = A} = app (app SS KK) (KK {B = A})
lam-sk zero = lam-sk-zero
lam-sk (next x) = app KK x
lam-sk SS = app KK SS
lam-sk KK = app KK KK
lam-sk (app x₁ x₂) = app (app SS (lam-sk x₁)) (lam-sk x₂)
⊢→⊢skC : Γ ⊢ A → Γ ⊢skC A
⊢→⊢skC zero = zero
⊢→⊢skC (next x) = next (⊢→⊢skC x)
⊢→⊢skC (lam x) = lam-sk (⊢→⊢skC x)
⊢→⊢skC (app x x₁) = app (⊢→⊢skC x) (⊢→⊢skC x₁)
⊢⇔⊢sk = ⟨ (λ x → skC→sk (⊢→⊢skC x)) , ⊢sk→⊢ ⟩