Organize modules

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Frederik Hanghøj Iversen 2017-11-10 16:00:00 +01:00
parent 37cb8e0541
commit 32244c912a
10 changed files with 493 additions and 510 deletions

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name: cat
include:
src
--libs/cubical-demo
-- description:
-- A formalization of category theory in Agda using cubical type theory.
depend:
agda-prelude
standard-library
--cubical-demo
cubical
include: src

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libs/cubical-demo

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{-# OPTIONS --cubical #-}
module Cat where
open import Agda.Primitive
open import Prelude.Function
open import PathPrelude
open ≡-Reasoning
-- Questions:
--
-- Is there a canonical `postulate trustme : {l : Level} {A : Set l} -> A`
-- in Agda (like undefined in Haskell).
--
-- Does Agda have a way to specify local submodules?
--
-- Can I open parts of a record, like say:
--
-- open Functor {{...}} ( fmap )
record Functor {a b} (F : Set a Set b) : Set (lsuc a b) where
field
-- morphisms
fmap : {A B} (A B) F A F B
-- laws
identity : { A : Set a }
-> id fmap (id { A = A })
fusion : { A B C : Set a } ( f : B -> C ) ( g : A -> B )
-> fmap f fmap g fmap (f g)
open Functor {{ ... }} hiding ( identity )
_<$>_ : {a b : Level} {F : Set a Set b} {{r : Functor F}} {A B : Set a} (A B) F A F B
_<$>_ = fmap
record Identity (A : Set) : Set where
constructor identity
field
runIdentity : A
open Identity {{...}}
instance
IdentityFunctor : Functor Identity
IdentityFunctor = record
{ fmap = λ { f (identity a) -> identity (f a) }
; identity = refl
; fusion = λ { f g -> refl }
}
data Maybe ( A : Set ) : Set where
nothing : Maybe A
just : A -> Maybe A
instance
MaybeFunctor : Functor Maybe
Functor.fmap MaybeFunctor f nothing = nothing
Functor.fmap MaybeFunctor f (just x) = just (f x)
Functor.identity MaybeFunctor = fun-ext (λ { nothing refl ; (just x) refl })
Functor.fusion MaybeFunctor f g = fun-ext (λ
-- QUESTION: Why does inlining `lem₀` give rise to an error?
{ nothing lem₀
; (just x) {! refl!}
{- ; (just x) → begin
(fmap f fmap g) (just x) ≡⟨⟩
(fmap f (fmap g (just x))) ≡⟨⟩
(fmap f (just (g x))) ≡⟨⟩
(just (f (g x))) ≡⟨⟩
just ((f g) x) ∎-}
})
where
lem₀ : nothing nothing
lem₀ = refl
-- `lem₁` and `fusionjust` are the same.
lem₁ : {A B C : Set} {f : B C} {g : A B} {x : A}
just (f (g x)) just (f (g x))
lem₁ = refl
fusionjust : { A B C : Set } { x : A } { f : B -> C } { g : A -> B }
-> (fmap f fmap g) (just x) just ((f g) x)
fusionjust {x = x} {f = f} {g = g} = begin
(fmap f fmap g) (just x) ≡⟨⟩
(fmap f (fmap g (just x))) ≡⟨⟩
(fmap f (just (g x))) ≡⟨⟩
(just (f (g x))) ≡⟨⟩
just ((f g) x)
record Applicative {a} (F : Set a -> Set a) : Set (lsuc a) where
field
-- morphisms
pure : { A : Set a } -> A -> F A
ap : { A B : Set a } -> F (A -> B) -> F A -> F B
-- laws
-- `ap-identity` is paraphrased from the documentation for Applicative on hackage.
ap-identity : { A : Set a } -> ap (pure (id { A = A })) id
composition : { A B C : Set a } ( u : F (B -> C) ) ( v : F (A -> B) ) ( w : F A )
-> ap (ap (ap (pure _∘_) u) v) w ap u (ap v w)
homomorphism : { A B : Set a } { a : A } { f : A -> B }
-> ap (pure f) (pure a) pure (f a)
interchange : { A B : Set a } ( u : F (A -> B) ) ( a : A )
-> ap u (pure a) ap (pure (_$ a)) u
open Applicative {{...}}
_<*>_ = ap
instance
IdentityApplicative : Applicative Identity
Applicative.pure IdentityApplicative = identity
Applicative.ap IdentityApplicative (identity f) (identity a) = identity (f a)
Applicative.ap-identity IdentityApplicative = refl
Applicative.composition IdentityApplicative _ _ _ = refl
Applicative.homomorphism IdentityApplicative = refl
Applicative.interchange IdentityApplicative _ _ = refl
-- QUESTION: Is this provable? How?
-- I suppose this would be `≡`'s functor-instance.
equiv-app : {A B : Set} -> {f g : A -> B} -> {a : A} -> f g -> f a g a
equiv-app f≡g = {!!}
instance
MaybeApplicative : Applicative Maybe
Applicative.pure MaybeApplicative = just
Applicative.ap MaybeApplicative nothing _ = nothing
Applicative.ap MaybeApplicative (just f) x = fmap f x
-- QUESTION: Why does termination-check fail when I use `refl` in both cases below?
Applicative.ap-identity MaybeApplicative = fun-ext (λ
{ nothing {!refl!}
; (just x) {!refl!}
})
Applicative.composition MaybeApplicative nothing v w = refl
Applicative.composition MaybeApplicative (just x) nothing w = refl
-- Easy-mode:
-- Applicative.composition MaybeApplicative {u = just f} {just g} {nothing} = refl
-- Applicative.composition MaybeApplicative {u = just f} {just g} {just x} = refl
-- Re-use mode:
-- QUESTION: What's wrong here?
Applicative.composition MaybeApplicative (just f) (just g) w = sym (equiv-app lem)
where
lem : {A B C} {f : B C} {g : A B} {w : Maybe A}
(fmap f) (fmap g)
(Functor.fmap MaybeFunctor (f g))
lem = Functor.fusion MaybeFunctor _ _
{-
Applicative.composition MaybeApplicative { u = u } { v = v } { w = w } = begin
ap (ap (ap (pure _∘_) u) v) w ≡⟨⟩
ap (ap (fmap _∘_ u) v) w ≡⟨ {!!}
{!!}
-}
Applicative.homomorphism MaybeApplicative = refl
Applicative.interchange MaybeApplicative nothing a = refl
Applicative.interchange MaybeApplicative (just x) a = refl

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{-# OPTIONS --cubical #-}
module Category where
open import Agda.Primitive
open import Data.Unit.Base
open import Data.Product
open import Cubical.PathPrelude
postulate undefined : { : Level} {A : Set } A
record Category { '} : Set (lsuc (' )) where
field
Object : Set
Arrow : Object Object Set '
𝟙 : {o : Object} Arrow o o
_⊕_ : { a b c : Object } Arrow b c Arrow a b Arrow a c
assoc : { A B C D : Object } { f : Arrow A B } { g : Arrow B C } { h : Arrow C D }
h (g f) (h g) f
ident : { A B : Object } { f : Arrow A B }
f 𝟙 f × 𝟙 f f
infixl 45 _⊕_
dom : { a b : Object } Arrow a b Object
dom {a = a} _ = a
cod : { a b : Object } Arrow a b Object
cod {b = b} _ = b
open Category public
record Functor {c c' d d'} (C : Category {c} {c'}) (D : Category {d} {d'})
: Set (c c' d d') where
private
open module C = Category C
open module D = Category D
field
F : C.Object D.Object
f : {c c' : C.Object} C.Arrow c c' D.Arrow (F c) (F c')
ident : { c : C.Object } f (C.𝟙 {c}) D.𝟙 {F c}
-- TODO: Avoid use of ugly explicit arguments somehow.
-- This guy managed to do it:
-- https://github.com/copumpkin/categories/blob/master/Categories/Functor/Core.agda
distrib : { c c' c'' : C.Object} {a : C.Arrow c c'} {a' : C.Arrow c' c''}
f (a' C.⊕ a) f a' D.⊕ f a
FunctorComp : { '} {a b c : Category {} {'}} Functor b c Functor a b Functor a c
FunctorComp {a = a} {b = b} {c = c} F G =
record
{ F = F.F G.F
; f = F.f G.f
; ident = λ { {c = obj}
let --t : (F.f ∘ G.f) (𝟙 a) ≡ (𝟙 c)
g-ident = G.ident
k : F.f (G.f {c' = obj} (𝟙 a)) F.f (G.f (𝟙 a))
k = refl {x = F.f (G.f (𝟙 a))}
t : F.f (G.f (𝟙 a)) (𝟙 c)
-- t = subst F.ident (subst G.ident k)
t = undefined
in t }
; distrib = undefined -- subst F.distrib (subst G.distrib refl)
}
where
open module F = Functor F
open module G = Functor G
-- The identity functor
Identity : { ' : Level} {C : Category {} {'}} Functor C C
Identity = record { F = λ x x ; f = λ x x ; ident = refl ; distrib = refl }
module _ { ' : Level} { : Category {} {'}} { A B : Object } where
private
open module = Category
_+_ = ._⊕_
Isomorphism : (f : .Arrow A B) Set '
Isomorphism f = Σ[ g .Arrow B A ] g + f .𝟙 × f + g .𝟙
Epimorphism : {X : .Object } (f : .Arrow A B) Set '
Epimorphism {X} f = ( g₀ g₁ : .Arrow B X ) g₀ + f g₁ + f g₀ g₁
Monomorphism : {X : .Object} (f : .Arrow A B) Set '
Monomorphism {X} f = ( g₀ g₁ : .Arrow X A ) f + g₀ f + g₁ g₀ g₁
iso-is-epi : {X} (f : .Arrow A B) Isomorphism f Epimorphism {X = X} f
-- Idea: Pre-compose with f- on both sides of the equality of eq to get
-- g₀ + f + f- ≡ g₁ + f + f-
-- which by left-inv reduces to the goal.
iso-is-epi f (f- , left-inv , right-inv) g₀ g₁ eq =
trans (sym (fst .ident))
( trans (cong (_+_ g₀) (sym right-inv))
( trans .assoc
( trans (cong (λ x x + f-) eq)
( trans (sym .assoc)
( trans (cong (_+_ g₁) right-inv) (fst .ident))
)
)
)
)
iso-is-mono : {X} (f : .Arrow A B ) Isomorphism f Monomorphism {X = X} f
-- For the next goal we do something similar: Post-compose with f- and use
-- right-inv to get the goal.
iso-is-mono f (f- , (left-inv , right-inv)) g₀ g₁ eq =
trans (sym (snd .ident))
( trans (cong (λ x x + g₀) (sym left-inv))
( trans (sym .assoc)
( trans (cong (_+_ f-) eq)
( trans .assoc
( trans (cong (λ x x + g₁) left-inv) (snd .ident)
)
)
)
)
)
iso-is-epi-mono : {X} (f : .Arrow A B ) Isomorphism f Epimorphism {X = X} f × Monomorphism {X = X} f
iso-is-epi-mono f iso = iso-is-epi f iso , iso-is-mono f iso
data : Set where
¬_ : { : Level} Set Set
¬ A = A
{-
epi-mono-is-not-iso : { '} ¬ (( : Category {} {'}) {A B X : Object } (f : Arrow A B ) Epimorphism { = } {X = X} f Monomorphism { = } {X = X} f Isomorphism { = } f)
epi-mono-is-not-iso f =
let k = f {!!} {!!} {!!} {!!}
in {!!}
-}
_≅_ : { ' : Level } { : Category {} {'} } ( A B : Object ) Set '
_≅_ { = } A B = Σ[ f .Arrow A B ] (Isomorphism { = } f)
where
open module = Category
Product : { : Level} ( C D : Category {} {} ) Category {} {}
Product C D =
record
{ Object = C.Object × D.Object
; Arrow = λ { (c , d) (c' , d')
let carr = C.Arrow c c'
darr = D.Arrow d d'
in carr × darr}
; 𝟙 = C.𝟙 , D.𝟙
; _⊕_ = λ { (bc∈C , bc∈D) (ab∈C , ab∈D) bc∈C C.⊕ ab∈C , bc∈D D.⊕ ab∈D}
; assoc = eqpair C.assoc D.assoc
; ident =
let (Cl , Cr) = C.ident
(Dl , Dr) = D.ident
in eqpair Cl Dl , eqpair Cr Dr
}
where
open module C = Category C
open module D = Category D
-- Two pairs are equal if their components are equal.
eqpair : { : Level} { A : Set } { B : Set } { a a' : A } { b b' : B } a a' b b' (a , b) (a' , b')
eqpair {a = a} {b = b} eqa eqb = subst eqa (subst eqb (refl {x = (a , b)}))
Opposite : { '} Category {} {'} Category {} {'}
Opposite =
record
{ Object = .Object
; Arrow = λ A B .Arrow B A
; 𝟙 = .𝟙
; _⊕_ = λ g f f .⊕ g
; assoc = sym .assoc
; ident = swap .ident
}
where
open module = Category
CatCat : { ' : Level} Category {-suc ( ')} { '}
CatCat {} {'} =
record
{ Object = Category {} {'}
; Arrow = Functor
; 𝟙 = Identity
; _⊕_ = FunctorComp
; assoc = undefined
; ident = λ { {f = f}
let eq : f f
eq = refl
in undefined , undefined}
}
Hom : { ' : Level} { : Category {} {'}} (A B : Object ) Set '
Hom { = } A B = Arrow A B
module _ { ' : Level} { : Category {} {'}} where
private
Obj = Object
Arr = Arrow
_+_ = _⊕_
HomFromArrow : (A : Obj) {B B' : Obj} (g : Arr B B')
Hom { = } A B Hom { = } A B'
HomFromArrow _A g = λ f g + f

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{-# OPTIONS --cubical #-}
open import Cubical.PathPrelude hiding ( Id )
module _ {A : Set} {a : A} {P : A Set} where
Q : A Set
Q a = A
t : Σ[ a A ] P a Q a
t (a , Pa) = a
u : Q a Σ[ a A ] P a
u a = a , {!!}
tu-bij : (a : Q a) (t u) a a
tu-bij a = refl
v : P a Q a
v x = {!!}
w : Q a P a
w x = {!!}
vw-bij : (a : P a) (w v) a a
vw-bij a = refl
-- tubij a with (t ∘ u) a
-- ... | q = {!!}
data Id {A : Set} (a : A) : Set where
id : A Id a
data Id' {A : Set} (a : A) : Set where
id' : A Id' a
T U : Set
T = Id a
U = Id' a
f : T U
f (id x) = id' x
g : U T
g (id' x) = id x
fg-bij : (x : U) (f g) x x
fg-bij (id' x) = {!!}

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module Category.Free where
open import Agda.Primitive
open import Cubical.PathPrelude hiding (Path)
open import Category as C
module _ { ' : Level} ( : Category {} {'}) where
private
open module = Category
Obj = .Object
Path : ( a b : Obj ) Set
Path a b = undefined
postulate emptyPath : (o : Obj) Path o o
postulate concatenate : {a b c : Obj} Path b c Path a b Path a c
private
module _ {A B C D : Obj} {r : Path A B} {q : Path B C} {p : Path C D} where
postulate
p-assoc : concatenate {A} {C} {D} p (concatenate {A} {B} {C} q r)
concatenate {A} {B} {D} (concatenate {B} {C} {D} p q) r
module _ {A B : Obj} {p : Path A B} where
postulate
ident-r : concatenate {A} {A} {B} p (emptyPath A) p
ident-l : concatenate {A} {B} {B} (emptyPath B) p p
Free : Category
Free = record
{ Object = Obj
; Arrow = Path
; 𝟙 = λ {o} emptyPath o
; _⊕_ = λ {a b c} concatenate {a} {b} {c}
; assoc = p-assoc
; ident = ident-r , ident-l
}

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{-# OPTIONS --cubical #-}
module Category.Pathy where
open import Cubical.PathPrelude
{-
module _ { '} {A : Set } {x : A}
(P : y x y Set ') (d : P x ((λ i x))) where
pathJ' : (y : A) (p : x y) P y p
pathJ' _ p = transp (λ i uncurry P (contrSingl p i)) d
pathJprop' : pathJ' _ refl d
pathJprop' i
= primComp (λ _ P x refl) i (λ {j (i = i1) d}) d
module _ { '} {A : Set }
(P : (x y : A) x y Set ') (d : (x : A) P x x refl) where
pathJ'' : (x y : A) (p : x y) P x y p
pathJ'' _ _ p = transp (λ i
let
P' = uncurry P
q = (contrSingl p i)
in
{!uncurry (uncurry P)!} ) d
-}
module _ { '} {A : Set }
(C : (x y : A) x y Set ')
(c : (x : A) C x x refl) where
=-ind : (x y : A) (p : x y) C x y p
=-ind x y p = pathJ (C x) (c x) y p
module _ { ' : Level} {A : Set } {P : A Set } {x y : A} where
private
D : (x y : A) (x y) Set
D x y p = P x P y
id : { : Level} {A : Set } A A
id x = x
d : (x : A) D x x refl
d x = id {A = P x}
-- the p refers to the third argument
liftP : x y P x P y
liftP p = =-ind D d x y p
-- lift' : (u : P x) → (p : x ≡ y) → (x , u) ≡ (y , liftP p u)
-- lift' u p = {!!}

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{-# OPTIONS --cubical #-}
module Category.Rel where
open import Data.Product
open import Cubical.PathPrelude
open import Cubical.GradLemma
open import Agda.Primitive
open import Category
-- Sets are built-in to Agda. The set of all small sets is called Set.
Fun : { : Level} ( T U : Set ) Set
Fun T U = T U
𝕊et-as-Cat : { : Level} Category {lsuc } {}
𝕊et-as-Cat {} = record
{ Object = Set
; Arrow = λ T U Fun {} T U
; 𝟙 = λ x x
; _⊕_ = λ g f x g ( f x )
; assoc = refl
; ident = funExt (λ x refl) , funExt (λ x refl)
}
-- Subsets are predicates over some type.
Subset : { : Level} ( A : Set ) Set ( lsuc lzero)
Subset A = A Set
-- Subset : { ' : Level} → ( A : Set ) → Set ( ⊔ lsuc ')
-- Subset {' = '} A = A → Set '
-- {a ∈ A | P a}
-- subset-syntax : { ' : Level} → (A : Set ) → (P : A → Set ') → ( a : A ) → Set '
-- subset-syntax A P a = P a
-- infix 2 subset-syntax
-- syntax subset P a = << a ∈ A >>>
-- syntax subset P = ⦃ a ∈ A | P a ⦄
-- syntax subset-syntax A (λ a → B) = ⟨ a foo A B ⟩
-- Membership is function applicatiom.
_∈_ : { : Level} {A : Set } A Subset A Set
s S = S s
infixl 45 _∈_
-- The diagnoal of a set is a synonym for equality.
Diag : S Subset (S × S)
Diag S (s₀ , s₁) = s₀ s₁
-- Diag S = subset (S × S) (λ {(p , q) → p ≡ q})
-- Diag S = ⟨ ? foo ? ? ⟩
-- Diag S (s₀ , s₁) = ⦃ (s₀ , s₁) ∈ S | s₀ ≡ s₁ ⦄
module _ {A B : Set} {S : Subset (A × B)} (ab : A × B) where
private
a : A
a = fst ab
b : B
b = snd ab
module _ where
private
forwards : ((a , b) S)
(Σ[ a' A ] (a , a') Diag A × (a' , b) S)
forwards ab∈S = a , (refl , ab∈S)
backwards : (Σ[ a' A ] (a , a') Diag A × (a' , b) S)
(a , b) S
backwards (a' , (a=a' , a'b∈S)) = subst (sym a=a') a'b∈S
isbijective : (x : (a , b) S) (backwards forwards) x x
-- isbijective x = pathJ (λ y x₁ → (backwards ∘ forwards) x ≡ x) {!!} {!!} {!!}
isbijective x = pathJprop (λ y _ y) x
postulate
back-fwd : (x : Σ[ a' A ] (a , a') Diag A × (a' , b) S)
(forwards backwards) x x
-- back-fwd (a , (p , ab∈S))
-- = =-ind (λ x y p → {!(forwards ∘ backwards) x ≡ x!}) {!!} {!!} {!!} p
-- = pathJprop (λ y _ → snd (snd y)) ab∈S
-- has type P x refl where P is the first argument
{-
module _ { '} {A : Set } {x : A}
(P : y x y Set ') (d : P x ((λ i x))) where
pathJ : (y : A) (p : x y) P y p
pathJ _ p = transp (λ i uncurry P (contrSingl p i)) d
pathJprop : pathJ _ refl d
pathJprop i = primComp (λ _ P x refl) i (λ {j (i = i1) d}) d
-}
isequiv : isEquiv
(Σ[ a' A ] (a , a') Diag A × (a' , b) S)
((a , b) S)
backwards
-- isequiv ab∈S = (forwards ab∈S , sym (isbijective ab∈S)) , λ y → fiberhelp y
isequiv y = gradLemma backwards forwards isbijective back-fwd y
equi : (Σ[ a' A ] (a , a') Diag A × (a' , b) S)
(a , b) S
equi = backwards , isequiv
ident-l : (Σ[ a' A ] (a , a') Diag A × (a' , b) S)
(a , b) S
ident-l = equivToPath equi
module _ where
private
forwards : ((a , b) S)
(Σ[ b' B ] (a , b') S × (b' , b) Diag B)
forwards proof = b , (proof , refl)
backwards : (Σ[ b' B ] (a , b') S × (b' , b) Diag B)
(a , b) S
backwards (b' , (ab'∈S , b'=b)) = subst b'=b ab'∈S
isbijective : (x : (a , b) S) (backwards forwards) x x
isbijective x = pathJprop (λ y _ y) x
fwd-bwd : (x : Σ[ b' B ] (a , b') S × (b' , b) Diag B)
(forwards backwards) x x
fwd-bwd (b , (ab∈S , refl)) = pathJprop (λ y _ fst (snd y)) ab∈S
isequiv : isEquiv
(Σ[ b' B ] (a , b') S × (b' , b) Diag B)
((a , b) S)
backwards
isequiv ab∈S = gradLemma backwards forwards isbijective fwd-bwd ab∈S
equi : (Σ[ b' B ] (a , b') S × (b' , b) Diag B)
ab S
equi = backwards , isequiv
ident-r : (Σ[ b' B ] (a , b') S × (b' , b) Diag B)
ab S
ident-r = equivToPath equi
Rel-as-Cat : Category
Rel-as-Cat = record
{ Object = Set
; Arrow = λ S R Subset (S × R)
; 𝟙 = λ {S} Diag S
; _⊕_ = λ {A B C} S R λ {( a , c ) Σ[ b B ] ( (a , b) R × (b , c) S )}
; assoc = {!!}
; ident = funExt ident-l , funExt ident-r
}
module _ { ' : Level} { : Category {} {}} where
private
C-Obj = Object
_+_ = Arrow
RepFunctor : Functor 𝕊et-as-Cat
RepFunctor =
record
{ F = λ A (B : C-Obj) Hom { = } A B
; f = λ { {c' = c'} f g HomFromArrow { = {!𝕊et-as-Cat!}} c' g}
; ident = {!!}
; distrib = {!!}
}

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{-# OPTIONS --cubical #-}
module PathPrelude where
open import Primitives public
open import Level
open import Data.Product using (Σ; _,_) renaming (proj₁ to fst; proj₂ to snd)
refl : {a} {A : Set a} {x : A} Path x x
refl {x = x} = λ i x
sym : {a} {A : Set a} {x y : A} Path x y Path y x
sym p = \ i p (~ i)
pathJ : {a}{p}{A : Set a}{x : A}(P : y Path x y Set p) P x ((\ i -> x)) y (p : Path x y) P y p
pathJ P d _ p = primComp (λ i P (p i) (\ j p (i j))) i0 (\ _ empty) d
pathJprop : {a}{p}{A : Set a}{x : A}(P : y Path x y Set p) (d : P x ((\ i -> x))) pathJ P d _ refl d
pathJprop {x = x} P d i = primComp (λ _ P x refl) i (\ { j (i = i1) d }) d
trans : {a} {A : Set a} {x y z : A} Path x y Path y z Path x z
trans {A = A} {x} {y} p q = \ i primComp (λ j A) (i ~ i)
(\ j \ { (i = i1) q j
; (i = i0) x
}
)
(p i)
fun-ext : {a b} {A : Set a} {B : A Set b} {f g : (x : A) B x}
( x Path (f x) (g x)) Path f g
fun-ext p = λ i x p x i
-- comp using only Path
compP : {a : Level} {A0 A1 : Set a} (A : Path A0 A1) {φ : I} (a0 : A i0) (Partial (Σ A1 \ y PathP (\ i A i) a0 y) φ) A i1
compP A {φ} a0 p = primComp (λ i A i) φ (\ i o p o .snd i) a0
-- fill using only Path
fillP : {a : Level} {A0 A1 : Set a} (A : Path A0 A1) {φ : I} (a0 : A i0) (Partial (Σ A1 \ y PathP (\ i A i) a0 y) φ) i A i
fillP A {φ} a0 p j = primComp (λ i A (i j)) (φ ~ j) (\ { i (φ = i1) p itIsOne .snd (i j); i (j = i0) a0 }) a0
reflId : {a} {A : Set a}{x : A} Id x x
reflId {x = x} = conid i1 (λ _ x)
Jdef : {a}{p}{A : Set a}{x : A}(P : y Id x y Set p) (d : P x reflId) J P d reflId d
Jdef P d = refl
fromPath : {A : Set}{x y : A} Path x y -> Id x y
fromPath p = conid i0 (\ i p i)
transId : {a} {A : Set a} {x y z : A} Id x y Id y z Id x z
transId {A = A} {x} {y} p = J (λ y _ Id x y) p
congId : {a b} {A : Set a} {B : Set b} (f : A B) {x y} Id x y Id (f x) (f y)
congId f {x} {y} = J (λ y _ Id (f x) (f y)) reflId
fill : {a : I -> Level} (A : (i : I) Set (a i)) (φ : I) ((i : I) Partial (A i) φ) A i0 (i : I) A i
fill A φ u a0 i = unsafeComp (\ j A (i j)) (φ ~ i) (\ j unsafePOr φ (~ i) (u (i j)) \ { _ a0 }) a0
singl : {l} {A : Set l} (a : A) -> Set l
singl {A = A} a = Σ A (\ x a x)
contrSingl : {l} {A : Set l} {a b : A} (p : a b) Path {A = singl a} (a , refl) (b , p)
contrSingl p = \ i ((p i) , \ j p (i j))
module Contr where
isContr : {a} (A : Set a) Set a
isContr A = Σ A (\ x y x y)
contr : {a} {A : Set a} isContr A (φ : I) (u : Partial A φ) A
contr {A = A} (c , p) φ u = primComp (\ _ A) φ (λ i \ o p (u o) i) c
lemma : {a} {A : Set a}
(contr1 : φ Partial A φ A)
(contr2 : u u (contr1 i1 \{_ u}))
isContr A
lemma {A = A} contr1 contr2 = x , (λ y let module M = R y in trans (contr2 x) (trans (\ i M.v i) (sym (contr2 y)))) where
x = contr1 i0 empty
module R (y : A) (i : I) where
φ = ~ i i
u : Partial A φ
u = primPOr (~ i) i (\{_ x}) (\{_ y})
v = contr1 φ u
isContrProp : {a} {A : Set a} (h : isContr A) -> (x y : A) x y
isContrProp {A = A} h a b = \ i primComp (\ _ A) _ (\ j [ (~ i) (\{_ snd h a j}) , i (\{_ snd h b j}) ]) (fst h)
module Pres {la lb : I _} {T : (i : I) Set (lb i)}{A : (i : I) Set (la i)} (f : i T i A i) (φ : I) (t : i Partial (T i) φ)
(t0 : T i0 {- [ φ ↦ t i0 ] -}) where
c1 c2 : A i1
c1 = unsafeComp A φ (λ i (\{_ f i (t i itIsOne) })) (f i0 t0)
c2 = f i1 (unsafeComp T φ t t0)
a0 = f i0 t0
a : i Partial (A i) φ
a i = (\{_ f i ((t i) itIsOne) })
u : i A i
u = fill A φ a a0
v : i T i
v = fill T φ t t0
pres : Path c1 c2
pres = \ j unsafeComp A (φ (j ~ j)) (λ i primPOr φ ((j ~ j)) (a i) (primPOr j (~ j) (\{_ f i (v i) }) (\{_ u i }))) a0
module Equiv {l l'} (A : Set l)(B : Set l') where
isEquiv : (A -> B) Set (l' l)
isEquiv f = y Contr.isContr (Σ A \ x y f x)
Equiv = Σ _ isEquiv
equiv : (f : Equiv) φ (t : Partial A φ) (a : B {- [ φ ↦ f t ] -}) PartialP φ (\ o Path a (fst f (t o)))
-> Σ A \ x a fst f x -- [ φ ↦ (t , \ j → a) ]
equiv (f , [f]) φ t a p = Contr.contr ([f] a) φ \ o t o , (\ i p o i)
equiv1 : (f : Equiv) φ (t : Partial A φ) (a : B {- [ φ ↦ f t ] -}) PartialP φ (\ o Path a (fst f (t o))) -> A
equiv1 f φ t a p = fst (equiv f φ t a p)
equiv2 : (f : Equiv) φ (t : Partial A φ) (a : B {- [ φ ↦ f t ] -}) (p : PartialP φ (\ o Path a (fst f (t o))))
a fst f (equiv1 f φ t a p)
equiv2 f φ t a p = snd (equiv f φ t a p)
open Equiv public
{-# BUILTIN ISEQUIV isEquiv #-}
idEquiv : {a} {A : Set a} Equiv A A
idEquiv = (λ x x) , (λ y (y , refl) , (λ y₁ contrSingl (snd y₁)))
pathToEquiv : {l : I _} (E : (i : I) Set (l i)) Equiv (E i0) (E i1)
pathToEquiv E = f
, (λ y (g y
, (\ j primComp E (~ j j) (\ i [ ~ j (\{_ v i y }) , j (\{_ u i (g y) }) ]) (g y))) ,
prop-f-image y _ )
where
A = E i0
B = E i1
transp : {l : I _} (E : (i : I) Set (l i)) E i0 E i1
transp E x = primComp E i0 (\ _ empty) x
f : A B
f = transp E
g : B A
g = transp (\ i E (~ i))
u : (i : I) A E i
u i x = fill E i0 (\ _ empty) x i
v : (i : I) B E i
v i y = fill (\ i E (~ i)) i0 (\ _ empty) y (~ i)
prop-f-image : (y : B) (a b : Σ _ \ x y f x) a b
prop-f-image y (x0 , b0) (x1 , b1) = \ k (w k) , (\ j d j k)
where
w0 = \ (j : I) primComp (\ i E (~ i)) (~ j j) ((\ i [ ~ j (\{_ v (~ i) y }) , j (\{_ u (~ i) x0 }) ])) (b0 j)
w1 = \ (j : I) primComp (\ i E (~ i)) (~ j j) ((\ i [ ~ j (\{_ v (~ i) y }) , j (\{_ u (~ i) x1 }) ])) (b1 j)
t0 = \ (j : I) fill (\ i E (~ i)) (~ j j) ((\ i [ ~ j (\{_ v (~ i) y }) , j (\{_ u (~ i) x0 }) ])) (b0 j)
t1 = \ (j : I) fill (\ i E (~ i)) (~ j j) ((\ i [ ~ j (\{_ v (~ i) y }) , j (\{_ u (~ i) x1 }) ])) (b1 j)
w = \ (k : I) primComp (λ _ A) (~ k k) (\ j [ ~ k (\{_ w0 j }) , k (\{_ w1 j }) ]) (g y)
t = \ (j k : I) fill (λ _ A) (~ k k) (\ j [ ~ k (\{_ w0 j }) , k (\{_ w1 j }) ]) (g y) j
d = \ (j k : I) primComp E ((~ k k) (~ j j)) ((\ i [ ~ k k [ ~ k (\{_ t0 j (~ i) }) , k (\{_ t1 j (~ i) }) ]
, ~ j j [ ~ j (\{_ v (i) y }) , j (\{_ u (i) (w k) }) ] ])) (t j k)
pathToEquiv2 : {l : I _} (E : (i : I) Set (l i)) _
pathToEquiv2 {l} E = snd (pathToEquiv E)
{-# BUILTIN PATHTOEQUIV pathToEquiv2 #-}
module GluePrims where
primitive
primGlue : {a b} (A : Set a) φ (T : Partial (Set b) φ) (f : PartialP φ (λ o T o A))
(pf : PartialP φ (λ o isEquiv (T o) A (f o))) Set b
prim^glue : {a b} {A : Set a} {φ : I} {T : Partial (Set b) φ}
{f : PartialP φ (λ o T o A)}
{pf : PartialP φ (λ o isEquiv (T o) A (f o))}
PartialP φ T A primGlue A φ T f pf
prim^unglue : {a b} {A : Set a} {φ : I} {T : Partial (Set b) φ}
{f : PartialP φ (λ o T o A)}
{pf : PartialP φ (λ o isEquiv (T o) A (f o))}
primGlue A φ T f pf A
module GluePrims' (dummy : Set) = GluePrims
open GluePrims' Set using () renaming (prim^glue to unsafeGlue) public
open GluePrims public renaming (prim^glue to glue; prim^unglue to unglue)
Glue : {a b} (A : Set a) φ (T : Partial (Set b) φ) (f : (PartialP φ \ o Equiv (T o) A)) Set _
Glue A φ T f = primGlue A φ T (\ o fst (f o)) (\ o snd (f o))
eqToPath' : {l} {A B : Set l} Equiv A B Path A B
eqToPath' {l} {A} {B} f = \ i Glue B (~ i i) ([ ~ i (\ _ A) , i (\ _ B) ]) ([ ~ i (\{_ f }) , i (\{_ idEquiv }) ])
primitive
primFaceForall : (I I) I
module FR (φ : I -> I) where
δ = primFaceForall φ
postulate
∀e : IsOne δ i IsOne (φ i)
∀∨ : i IsOne (φ i) IsOne ((δ (φ i0 ~ i)) (φ i1 i))
module GlueIso {a b} {A : Set a} {φ : I} {T : Partial (Set b) φ} {f : (PartialP φ \ o Equiv (T o) A)} where
going : PartialP φ (\ o Glue A φ T f T o)
going = (\{_ (\ x x) })
back : PartialP φ (\ o T o Glue A φ T f)
back = (\{_ (\ x x) })
lemma : (b : PartialP φ (\ _ Glue A φ T f)) PartialP φ \ o Path (unglue {φ = φ} (b o)) (fst (f o) (going o (b o)))
lemma b = (\{_ refl })
module CompGlue {la lb : I _} (A : (i : I) Set (la i)) (φ : I -> I) (T : i Partial (Set (lb i)) (φ i))
(f : i PartialP (φ i) \ o Equiv (T i o) (A i)) where
B : (i : I) -> Set (lb i)
B = \ i Glue (A i) (φ i) (T i) (f i)
module Local (ψ : I) (b : i Partial (B i) ψ) (b0 : B i0 {- [ ψ ↦ b i0 ] -}) where
a : i Partial (A i) ψ
a i = \ o unglue {φ = φ i} (b i o)
module Forall (δ : I) (e : IsOne δ i IsOne (φ i)) where
a0 : A i0
a0 = unglue {φ = φ i0} b0
a₁' = unsafeComp A ψ a a0
t₁' : PartialP δ (\ o T i1 (e o i1))
t₁' = \ o unsafeComp (λ i T i (e o i)) ψ (\ i o' GlueIso.going {φ = φ i} (e o i) (b i o')) (GlueIso.going {φ = φ i0} (e o i0) b0)
w : PartialP δ _
w = \ o Pres.pres (\ i fst (f i (e o i))) ψ (λ i x GlueIso.going {φ = φ i} (e o i) (b i x)) (GlueIso.going {φ = φ i0} (e o i0) b0)
a₁'' = unsafeComp (\ _ A i1) (δ ψ) (\ j unsafePOr δ ψ (\ o w o j) (a i1)) a₁'
g : PartialP (φ i1) _
g o = (equiv (T i1 _) (A i1) (f i1 o) (δ ψ) (unsafePOr δ ψ t₁' (\ o' GlueIso.going {φ = φ i1} o (b i1 o'))) a₁''
( (unsafePOr δ ψ (\{ (δ = i1) refl }) ((\{ (ψ = i1) GlueIso.lemma {φ = φ i1} (\ _ b i1 itIsOne) o }) ) ) ))
-- TODO figure out why we need (δ = i1) and (ψ = i1) here
t₁ : PartialP (φ i1) _
t₁ o = fst (g o)
α : PartialP (φ i1) _
α o = snd (g o)
a₁ = unsafeComp (\ j A i1) (φ i1 ψ) (\ j unsafePOr (φ i1) ψ (\ o α o j) (a i1)) a₁''
b₁ : Glue _ (φ i1) (T i1) (f i1)
b₁ = unsafeGlue {φ = φ i1} t₁ a₁
b1 = Forall.b₁ (FR.δ φ) (FR.∀e φ)
compGlue : {la lb : I _} (A : (i : I) Set (la i)) (φ : I -> I) (T : i Partial (Set (lb i)) (φ i))
(f : i PartialP (φ i) \ o (T i o) (A i))
(pf : i PartialP (φ i) (λ o isEquiv (T i o) (A i) (f i o)))
let
B : (i : I) -> Set (lb i)
B = \ i primGlue (A i) (φ i) (T i) (f i) (pf i)
in (ψ : I) (b : i Partial (B i) ψ) (b0 : B i0) B i1
compGlue A φ T f pf ψ b b0 = CompGlue.Local.b1 A φ T (λ i p (f i p) , (pf i p)) ψ b b0
{-# BUILTIN COMPGLUE compGlue #-}
module ≡-Reasoning {a} {A : Set a} where
infix 3 _∎
infixr 2 _≡⟨⟩_ _≡⟨_⟩_ -- _≅⟨_⟩_
infix 1 begin_
begin_ : {x y : A} x y x y
begin_ x≡y = x≡y
_≡⟨⟩_ : (x {y} : A) x y x y
_ ≡⟨⟩ x≡y = x≡y
_≡⟨_⟩_ : (x {y z} : A) x y y z x z
_ ≡⟨ x≡y y≡z = trans x≡y y≡z
-- _≅⟨_⟩_ : ∀ (x {y z} : A) → x ≅ y → y ≡ z → x ≡ z
-- _ ≅⟨ x≅y ⟩ y≡z = trans (H.≅-to-≡ x≅y) y≡z
_∎ : (x : A) x x
_∎ _ = refl

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{-# OPTIONS --cubical #-}
module Primitives where
module Postulates where
open import Agda.Primitive public
open CubicalPrimitives public renaming (isOneEmpty to empty)
postulate
Path : {a} {A : Set a} A A Set a
PathP : {a} (A : I Set a) A i0 A i1 Set a
{-# BUILTIN PATH Path #-}
{-# BUILTIN PATHP PathP #-}
primitive
primPathApply : {a} {A : Set a} {x y : A} Path x y I A
primPathPApply : {a} {A : I Set a} {x y} PathP A x y (i : I) A i
postulate
Id : {a} {A : Set a} A A Set a
{-# BUILTIN ID Id #-}
{-# BUILTIN CONID conid #-}
primitive
primDepIMin : _
primIdFace : {a : Level} {A : Set a} {x y : A} Id x y I
primIdPath : {a : Level} {A : Set a} {x y : A} Id x y Path x y
primitive
primIdJ : {a}{p}{A : Set a}{x : A}(P : y Id x y Set p) P x (conid i1 (\ i -> x)) {y} (p : Id x y) P y p
{-# BUILTIN SUB Sub #-}
postulate
inc : {a} {A : Set a} {φ} (x : A) Sub {A = A} φ (\ _ x)
{-# BUILTIN SUBIN inc #-}
primitive
primSubOut : {a : Level} {A : Set a} {φ : I} {u : Partial A φ} Sub φ u A
open Postulates public renaming (primPathApply to _∙_; primIMin to _∧_; primIMax to __; primINeg to ~_
; primPFrom1 to p[_]
; primIdJ to J
; primSubOut to ouc
; Path to Path'
)
module Unsafe' (dummy : Set) = Postulates
unsafeComp = Unsafe'.primComp Set
unsafePOr = Unsafe'.primPOr Set
Path : {a} {A : Set a} A A Set a
Path {A = A} = PathP (\ _ A)
infix 4 _≡_
_≡_ = Path