Split Category into RawCategory and IsCategory
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@ -12,7 +12,7 @@ open import Function
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open import Relation.Nullary
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open import Relation.Nullary.Decidable
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open import Cat.Category hiding (Hom)
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open import Cat.Category
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open import Cat.Functor
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open import Cat.Equality
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open Equality.Data.Product
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@ -66,12 +66,14 @@ module _ {ℓ ℓ' : Level} (Ns : Set ℓ) where
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Hom = Σ Hom' rules
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-- The category of names and substitutions
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ℂ : Category ℓ ℓ -- ℓo (lsuc lzero ⊔ ℓo)
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ℂ = record
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Rawℂ : RawCategory ℓ ℓ -- ℓo (lsuc lzero ⊔ ℓo)
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Rawℂ = record
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{ Object = FiniteDecidableSubset
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-- { Object = Ns → Bool
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; Arrow = Hom
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; 𝟙 = λ { {o} → inj₁ , λ { (i , ii) (j , jj) eq → Σ≡ eq {!refl!} } }
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; _∘_ = {!!}
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; isCategory = {!!}
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}
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postulate RawIsCategoryℂ : IsCategory Rawℂ
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ℂ : Category ℓ ℓ
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ℂ = Rawℂ , RawIsCategoryℂ
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@ -13,36 +13,42 @@ open Equality.Data.Product
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module _ (ℓa ℓb : Level) where
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private
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Obj = Σ[ A ∈ Set ℓa ] (A → Set ℓb)
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Arr : Obj → Obj → Set (ℓa ⊔ ℓb)
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Obj' = Σ[ A ∈ Set ℓa ] (A → Set ℓb)
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Arr : Obj' → Obj' → Set (ℓa ⊔ ℓb)
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Arr (A , B) (A' , B') = Σ[ f ∈ (A → A') ] ({x : A} → B x → B' (f x))
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one : {o : Obj} → Arr o o
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one : {o : Obj'} → Arr o o
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proj₁ one = λ x → x
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proj₂ one = λ b → b
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_∘_ : {a b c : Obj} → Arr b c → Arr a b → Arr a c
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_∘_ : {a b c : Obj'} → Arr b c → Arr a b → Arr a c
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(g , g') ∘ (f , f') = g Function.∘ f , g' Function.∘ f'
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_⟨_∘_⟩ : {a b : Obj} → (c : Obj) → Arr b c → Arr a b → Arr a c
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_⟨_∘_⟩ : {a b : Obj'} → (c : Obj') → Arr b c → Arr a b → Arr a c
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c ⟨ g ∘ f ⟩ = _∘_ {c = c} g f
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module _ {A B C D : Obj} {f : Arr A B} {g : Arr B C} {h : Arr C D} where
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module _ {A B C D : Obj'} {f : Arr A B} {g : Arr B C} {h : Arr C D} where
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assoc : (D ⟨ h ∘ C ⟨ g ∘ f ⟩ ⟩) ≡ D ⟨ D ⟨ h ∘ g ⟩ ∘ f ⟩
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assoc = Σ≡ refl refl
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module _ {A B : Obj} {f : Arr A B} where
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module _ {A B : Obj'} {f : Arr A B} where
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ident : B ⟨ f ∘ one ⟩ ≡ f × B ⟨ one {B} ∘ f ⟩ ≡ f
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ident = (Σ≡ refl refl) , Σ≡ refl refl
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instance
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isCategory : IsCategory Obj Arr one (λ {a b c} → _∘_ {a} {b} {c})
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isCategory = record
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{ assoc = λ {A} {B} {C} {D} {f} {g} {h} → assoc {D = D} {f} {g} {h}
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; ident = λ {A} {B} {f} → ident {A} {B} {f = f}
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}
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Fam : Category (lsuc (ℓa ⊔ ℓb)) (ℓa ⊔ ℓb)
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Fam = record
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{ Object = Obj
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RawFam : RawCategory (lsuc (ℓa ⊔ ℓb)) (ℓa ⊔ ℓb)
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RawFam = record
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{ Object = Obj'
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; Arrow = Arr
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; 𝟙 = one
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; _∘_ = λ {a b c} → _∘_ {a} {b} {c}
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}
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instance
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isCategory : IsCategory RawFam
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isCategory = record
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{ assoc = λ {A} {B} {C} {D} {f} {g} {h} → assoc {D = D} {f} {g} {h}
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; ident = λ {A} {B} {f} → ident {A} {B} {f = f}
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; arrow-is-set = ?
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; univalent = ?
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}
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Fam : Category (lsuc (ℓa ⊔ ℓb)) (ℓa ⊔ ℓb)
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Fam = RawFam , isCategory
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@ -53,7 +53,7 @@ module _ {ℓc ℓc' ℓd ℓd' : Level} {ℂ : Category ℓc ℓc'} {𝔻 : Cat
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𝔻 [ F→ f ∘ identityTrans F A ] ∎
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where
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F→ = F .func→
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module 𝔻 = IsCategory (𝔻 .isCategory)
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module 𝔻 = IsCategory (isCategory 𝔻)
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identityNat : (F : Functor ℂ 𝔻) → NaturalTransformation F F
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identityNat F = identityTrans F , identityNatural F
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@ -75,7 +75,7 @@ module _ {ℓc ℓc' ℓd ℓd' : Level} {ℂ : Category ℓc ℓc'} {𝔻 : Cat
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𝔻 [ H .func→ f ∘ 𝔻 [ θ A ∘ η A ] ] ≡⟨⟩
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𝔻 [ H .func→ f ∘ (θ ∘nt η) A ] ∎
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where
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open IsCategory (𝔻 .isCategory)
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open IsCategory (isCategory 𝔻)
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NatComp = _:⊕:_
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@ -96,29 +96,33 @@ module _ {ℓc ℓc' ℓd ℓd' : Level} {ℂ : Category ℓc ℓc'} {𝔻 : Cat
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× (_:⊕:_ {A} {B} {B} (identityNat B) f) ≡ f
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:ident: = ident-r , ident-l
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instance
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:isCategory: : IsCategory (Functor ℂ 𝔻) NaturalTransformation
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(λ {F} → identityNat F) (λ {a} {b} {c} → _:⊕:_ {a} {b} {c})
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:isCategory: = record
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{ assoc = λ {A B C D} → :assoc: {A} {B} {C} {D}
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; ident = λ {A B} → :ident: {A} {B}
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}
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-- Functor categories. Objects are functors, arrows are natural transformations.
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Fun : Category (ℓc ⊔ ℓc' ⊔ ℓd ⊔ ℓd') (ℓc ⊔ ℓc' ⊔ ℓd')
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Fun = record
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RawFun : RawCategory (ℓc ⊔ ℓc' ⊔ ℓd ⊔ ℓd') (ℓc ⊔ ℓc' ⊔ ℓd')
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RawFun = record
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{ Object = Functor ℂ 𝔻
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; Arrow = NaturalTransformation
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; 𝟙 = λ {F} → identityNat F
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; _∘_ = λ {F G H} → _:⊕:_ {F} {G} {H}
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}
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instance
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:isCategory: : IsCategory RawFun
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:isCategory: = record
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{ assoc = λ {A B C D} → :assoc: {A} {B} {C} {D}
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; ident = λ {A B} → :ident: {A} {B}
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; arrow-is-set = ?
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; univalent = ?
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}
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Fun : Category (ℓc ⊔ ℓc' ⊔ ℓd ⊔ ℓd') (ℓc ⊔ ℓc' ⊔ ℓd')
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Fun = RawFun , :isCategory:
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module _ {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') where
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open import Cat.Categories.Sets
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-- Restrict the functors to Presheafs.
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Presh : Category (ℓ ⊔ lsuc ℓ') (ℓ ⊔ ℓ')
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Presh = record
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RawPresh : RawCategory (ℓ ⊔ lsuc ℓ') (ℓ ⊔ ℓ')
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RawPresh = record
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{ Object = Presheaf ℂ
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; Arrow = NaturalTransformation
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; 𝟙 = λ {F} → identityNat F
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@ -154,16 +154,18 @@ module _ {A B C D : Set} {S : Subset (A × B)} {R : Subset (B × C)} {Q : Subset
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≡ (Σ[ b ∈ B ] (a , b) ∈ S × (Σ[ c ∈ C ] (b , c) ∈ R × (c , d) ∈ Q))
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is-assoc = equivToPath equi
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Rel : Category (lsuc lzero) (lsuc lzero)
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Rel = record
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RawRel : RawCategory (lsuc lzero) (lsuc lzero)
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RawRel = record
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{ Object = Set
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; Arrow = λ S R → Subset (S × R)
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; 𝟙 = λ {S} → Diag S
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; _∘_ = λ {A B C} S R → λ {( a , c ) → Σ[ b ∈ B ] ( (a , b) ∈ R × (b , c) ∈ S )}
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; isCategory = record
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}
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RawIsCategoryRel : IsCategory RawRel
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RawIsCategoryRel = record
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{ assoc = funExt is-assoc
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; ident = funExt ident-l , funExt ident-r
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; arrow-is-set = {!!}
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; univalent = {!!}
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}
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}
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@ -4,22 +4,31 @@ module Cat.Categories.Sets where
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open import Cubical
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open import Agda.Primitive
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open import Data.Product
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import Function
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open import Cat.Category
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open import Cat.Functor
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open Category
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module _ {ℓ : Level} where
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Sets : Category (lsuc ℓ) ℓ
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Sets = record
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SetsRaw : RawCategory (lsuc ℓ) ℓ
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SetsRaw = record
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{ Object = Set ℓ
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; Arrow = λ T U → T → U
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; 𝟙 = id
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; _∘_ = _∘′_
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; isCategory = record { assoc = refl ; ident = funExt (λ _ → refl) , funExt (λ _ → refl) }
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; 𝟙 = Function.id
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; _∘_ = Function._∘′_
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}
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where
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open import Function
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SetsIsCategory : IsCategory SetsRaw
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SetsIsCategory = record
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{ assoc = refl
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; ident = funExt (λ _ → refl) , funExt (λ _ → refl)
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; arrow-is-set = {!!}
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; univalent = {!!}
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}
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Sets : Category (lsuc ℓ) ℓ
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Sets = SetsRaw , SetsIsCategory
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private
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module _ {X A B : Set ℓ} (f : X → A) (g : X → B) where
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@ -55,7 +64,7 @@ representable {ℂ = ℂ} A = record
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}
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}
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where
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open IsCategory (ℂ .isCategory)
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open IsCategory (isCategory ℂ)
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-- Contravariant Presheaf
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Presheaf : ∀ {ℓ ℓ'} (ℂ : Category ℓ ℓ') → Set (ℓ ⊔ lsuc ℓ')
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@ -72,4 +81,4 @@ presheaf {ℂ = ℂ} B = record
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}
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}
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where
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open IsCategory (ℂ .isCategory)
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open IsCategory (isCategory ℂ)
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@ -23,18 +23,37 @@ open import Cubical.GradLemma using ( propIsEquiv )
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syntax ∃!-syntax (λ x → B) = ∃![ x ] B
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record RawCategory (ℓ ℓ' : Level) : Set (lsuc (ℓ' ⊔ ℓ)) where
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-- adding no-eta-equality can speed up type-checking.
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-- ONLY IF you define your categories with copatterns though.
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no-eta-equality
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field
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-- Need something like:
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-- Object : Σ (Set ℓ) isGroupoid
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Object : Set ℓ
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-- And:
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-- Arrow : Object → Object → Σ (Set ℓ') isSet
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Arrow : Object → Object → Set ℓ'
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𝟙 : {o : Object} → Arrow o o
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_∘_ : {A B C : Object} → Arrow B C → Arrow A B → Arrow A C
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infixl 10 _∘_
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domain : { a b : Object } → Arrow a b → Object
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domain {a = a} _ = a
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codomain : { a b : Object } → Arrow a b → Object
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codomain {b = b} _ = b
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-- Thierry: All projections must be `isProp`'s
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-- According to definitions 9.1.1 and 9.1.6 in the HoTT book the
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-- arrows of a category form a set (arrow-is-set), and there is an
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-- equivalence between the equality of objects and isomorphisms
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-- (univalent).
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record IsCategory {ℓ ℓ' : Level}
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(Object : Set ℓ)
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(Arrow : Object → Object → Set ℓ')
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(𝟙 : {o : Object} → Arrow o o)
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(_∘_ : { a b c : Object } → Arrow b c → Arrow a b → Arrow a c)
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: Set (lsuc (ℓ' ⊔ ℓ)) where
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record IsCategory {ℓa ℓb : Level} (ℂ : RawCategory ℓa ℓb) : Set (lsuc (ℓa ⊔ ℓb)) where
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open RawCategory ℂ
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-- (Object : Set ℓ)
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-- (Arrow : Object → Object → Set ℓ')
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-- (𝟙 : {o : Object} → Arrow o o)
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-- (_∘_ : { a b c : Object } → Arrow b c → Arrow a b → Arrow a c)
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field
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assoc : {A B C D : Object} { f : Arrow A B } { g : Arrow B C } { h : Arrow C D }
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→ h ∘ (g ∘ f) ≡ (h ∘ g) ∘ f
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@ -42,10 +61,10 @@ record IsCategory {ℓ ℓ' : Level}
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→ f ∘ 𝟙 ≡ f × 𝟙 ∘ f ≡ f
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arrow-is-set : ∀ {A B : Object} → isSet (Arrow A B)
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Isomorphism : ∀ {A B} → (f : Arrow A B) → Set ℓ'
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Isomorphism : ∀ {A B} → (f : Arrow A B) → Set ℓb
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Isomorphism {A} {B} f = Σ[ g ∈ Arrow B A ] g ∘ f ≡ 𝟙 × f ∘ g ≡ 𝟙
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_≅_ : (A B : Object) → Set ℓ'
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_≅_ : (A B : Object) → Set ℓb
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_≅_ A B = Σ[ f ∈ Arrow A B ] (Isomorphism f)
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idIso : (A : Object) → A ≅ A
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@ -61,20 +80,16 @@ record IsCategory {ℓ ℓ' : Level}
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univalent : {A B : Object} → isEquiv (A ≡ B) (A ≅ B) (id-to-iso A B)
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module _ {A B : Object} where
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Epimorphism : {X : Object } → (f : Arrow A B) → Set ℓ'
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Epimorphism : {X : Object } → (f : Arrow A B) → Set ℓb
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Epimorphism {X} f = ( g₀ g₁ : Arrow B X ) → g₀ ∘ f ≡ g₁ ∘ f → g₀ ≡ g₁
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Monomorphism : {X : Object} → (f : Arrow A B) → Set ℓ'
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Monomorphism : {X : Object} → (f : Arrow A B) → Set ℓb
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Monomorphism {X} f = ( g₀ g₁ : Arrow X A ) → f ∘ g₀ ≡ f ∘ g₁ → g₀ ≡ g₁
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module _ {ℓ} {ℓ'} {Object : Set ℓ}
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{Arrow : Object → Object → Set ℓ'}
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{𝟙 : {o : Object} → Arrow o o}
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{_⊕_ : { a b c : Object } → Arrow b c → Arrow a b → Arrow a c}
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where
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module _ {ℓa} {ℓb} {ℂ : RawCategory ℓa ℓb} where
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-- TODO, provable by using arrow-is-set and that isProp (isEquiv _ _ _)
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-- This lemma will be useful to prove the equality of two categories.
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IsCategory-is-prop : isProp (IsCategory Object Arrow 𝟙 _⊕_)
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IsCategory-is-prop : isProp (IsCategory ℂ)
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IsCategory-is-prop x y i = record
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{ assoc = x.arrow-is-set _ _ x.assoc y.assoc i
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; ident =
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@ -94,38 +109,32 @@ module _ {ℓ} {ℓ'} {Object : Set ℓ}
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module x = IsCategory x
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module y = IsCategory y
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record Category (ℓ ℓ' : Level) : Set (lsuc (ℓ' ⊔ ℓ)) where
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-- adding no-eta-equality can speed up type-checking.
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-- ONLY IF you define your categories with copatterns though.
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no-eta-equality
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field
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-- Need something like:
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-- Object : Σ (Set ℓ) isGroupoid
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Object : Set ℓ
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-- And:
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-- Arrow : Object → Object → Σ (Set ℓ') isSet
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Arrow : Object → Object → Set ℓ'
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𝟙 : {o : Object} → Arrow o o
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_∘_ : {A B C : Object} → Arrow B C → Arrow A B → Arrow A C
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{{isCategory}} : IsCategory Object Arrow 𝟙 _∘_
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infixl 10 _∘_
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domain : { a b : Object } → Arrow a b → Object
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domain {a = a} _ = a
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codomain : { a b : Object } → Arrow a b → Object
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codomain {b = b} _ = b
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Category : (ℓa ℓb : Level) → Set (lsuc (ℓa ⊔ ℓb))
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Category ℓa ℓb = Σ (RawCategory ℓa ℓb) IsCategory
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open Category
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module Category {ℓa ℓb : Level} (ℂ : Category ℓa ℓb) where
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raw = fst ℂ
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open RawCategory raw public
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isCategory = snd ℂ
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_[_,_] : ∀ {ℓ ℓ'} → (ℂ : Category ℓ ℓ') → (A : ℂ .Object) → (B : ℂ .Object) → Set ℓ'
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_[_,_] = Arrow
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open RawCategory
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_[_∘_] : ∀ {ℓ ℓ'} → (ℂ : Category ℓ ℓ') → {A B C : ℂ .Object} → (g : ℂ [ B , C ]) → (f : ℂ [ A , B ]) → ℂ [ A , C ]
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_[_∘_] = _∘_
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-- _∈_ : ∀ {ℓa ℓb} (ℂ : Category ℓa ℓb) → (ℂ .fst .Object → Set ℓb) → Set (ℓa ⊔ ℓb)
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-- A ∈ ℂ =
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module _ {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') {A B obj : Object ℂ} where
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IsProduct : (π₁ : Arrow ℂ obj A) (π₂ : Arrow ℂ obj B) → Set (ℓ ⊔ ℓ')
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Obj : ∀ {ℓa ℓb} → Category ℓa ℓb → Set ℓa
|
||||
Obj ℂ = ℂ .fst .Object
|
||||
|
||||
_[_,_] : ∀ {ℓ ℓ'} → (ℂ : Category ℓ ℓ') → (A : Obj ℂ) → (B : Obj ℂ) → Set ℓ'
|
||||
ℂ [ A , B ] = ℂ .fst .Arrow A B
|
||||
|
||||
_[_∘_] : ∀ {ℓ ℓ'} → (ℂ : Category ℓ ℓ') → {A B C : Obj ℂ} → (g : ℂ [ B , C ]) → (f : ℂ [ A , B ]) → ℂ [ A , C ]
|
||||
ℂ [ g ∘ f ] = ℂ .fst ._∘_ g f
|
||||
|
||||
module _ {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') {A B obj : Obj ℂ} where
|
||||
IsProduct : (π₁ : ℂ [ obj , A ]) (π₂ : ℂ [ obj , B ]) → Set (ℓ ⊔ ℓ')
|
||||
IsProduct π₁ π₂
|
||||
= ∀ {X : ℂ .Object} (x₁ : ℂ .Arrow X A) (x₂ : ℂ .Arrow X B)
|
||||
= ∀ {X : Obj ℂ} (x₁ : ℂ [ X , A ]) (x₂ : ℂ [ X , B ])
|
||||
→ ∃![ x ] (ℂ [ π₁ ∘ x ] ≡ x₁ × ℂ [ π₂ ∘ x ] ≡ x₂)
|
||||
|
||||
-- Tip from Andrea; Consider this style for efficiency:
|
||||
|
|
@ -135,48 +144,55 @@ module _ {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') {A B obj : Object ℂ} whe
|
|||
-- isProduct : ∀ {X : ℂ .Object} (x₁ : ℂ .Arrow X A) (x₂ : ℂ .Arrow X B)
|
||||
-- → ∃![ x ] (ℂ ._⊕_ π₁ x ≡ x₁ × ℂ. _⊕_ π₂ x ≡ x₂)
|
||||
|
||||
record Product {ℓ ℓ' : Level} {ℂ : Category ℓ ℓ'} (A B : ℂ .Object) : Set (ℓ ⊔ ℓ') where
|
||||
record Product {ℓ ℓ' : Level} {ℂ : Category ℓ ℓ'} (A B : Obj ℂ) : Set (ℓ ⊔ ℓ') where
|
||||
no-eta-equality
|
||||
field
|
||||
obj : ℂ .Object
|
||||
proj₁ : ℂ .Arrow obj A
|
||||
proj₂ : ℂ .Arrow obj B
|
||||
obj : Obj ℂ
|
||||
proj₁ : ℂ [ obj , A ]
|
||||
proj₂ : ℂ [ obj , B ]
|
||||
{{isProduct}} : IsProduct ℂ proj₁ proj₂
|
||||
|
||||
arrowProduct : ∀ {X} → (π₁ : Arrow ℂ X A) (π₂ : Arrow ℂ X B)
|
||||
→ Arrow ℂ X obj
|
||||
arrowProduct : ∀ {X} → (π₁ : ℂ [ X , A ]) (π₂ : ℂ [ X , B ])
|
||||
→ ℂ [ X , obj ]
|
||||
arrowProduct π₁ π₂ = fst (isProduct π₁ π₂)
|
||||
|
||||
record HasProducts {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') : Set (ℓ ⊔ ℓ') where
|
||||
field
|
||||
product : ∀ (A B : ℂ .Object) → Product {ℂ = ℂ} A B
|
||||
product : ∀ (A B : Obj ℂ) → Product {ℂ = ℂ} A B
|
||||
|
||||
open Product
|
||||
|
||||
objectProduct : (A B : ℂ .Object) → ℂ .Object
|
||||
objectProduct : (A B : Obj ℂ) → Obj ℂ
|
||||
objectProduct A B = Product.obj (product A B)
|
||||
-- The product mentioned in awodey in Def 6.1 is not the regular product of arrows.
|
||||
-- It's a "parallel" product
|
||||
parallelProduct : {A A' B B' : ℂ .Object} → ℂ .Arrow A A' → ℂ .Arrow B B'
|
||||
→ ℂ .Arrow (objectProduct A B) (objectProduct A' B')
|
||||
parallelProduct : {A A' B B' : Obj ℂ} → ℂ [ A , A' ] → ℂ [ B , B' ]
|
||||
→ ℂ [ objectProduct A B , objectProduct A' B' ]
|
||||
parallelProduct {A = A} {A' = A'} {B = B} {B' = B'} a b = arrowProduct (product A' B')
|
||||
(ℂ [ a ∘ (product A B) .proj₁ ])
|
||||
(ℂ [ b ∘ (product A B) .proj₂ ])
|
||||
|
||||
module _ {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') where
|
||||
Opposite : Category ℓ ℓ'
|
||||
Opposite =
|
||||
record
|
||||
module _ {ℓa ℓb : Level} (ℂ : Category ℓa ℓb) where
|
||||
private
|
||||
open Category ℂ
|
||||
module ℂ = RawCategory (ℂ .fst)
|
||||
OpRaw : RawCategory ℓa ℓb
|
||||
OpRaw = record
|
||||
{ Object = ℂ.Object
|
||||
; Arrow = Function.flip (ℂ .Arrow)
|
||||
; Arrow = Function.flip ℂ.Arrow
|
||||
; 𝟙 = ℂ.𝟙
|
||||
; _∘_ = Function.flip (ℂ._∘_)
|
||||
; isCategory = record { assoc = sym assoc ; ident = swap ident
|
||||
; arrow-is-set = {!!}
|
||||
; univalent = {!!} }
|
||||
}
|
||||
where
|
||||
open IsCategory (ℂ .isCategory)
|
||||
open IsCategory isCategory
|
||||
OpIsCategory : IsCategory OpRaw
|
||||
OpIsCategory = record
|
||||
{ assoc = sym assoc
|
||||
; ident = swap ident
|
||||
; arrow-is-set = {!!}
|
||||
; univalent = {!!}
|
||||
}
|
||||
Opposite : Category ℓa ℓb
|
||||
Opposite = OpRaw , OpIsCategory
|
||||
|
||||
-- A consequence of no-eta-equality; `Opposite-is-involution` is no longer
|
||||
-- definitional - i.e.; you must match on the fields:
|
||||
|
|
@ -189,42 +205,34 @@ module _ {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') where
|
|||
-- assoc (Opposite-is-involution i) = {!!}
|
||||
-- ident (Opposite-is-involution i) = {!!}
|
||||
|
||||
Hom : {ℓ ℓ' : Level} → (ℂ : Category ℓ ℓ') → (A B : Object ℂ) → Set ℓ'
|
||||
Hom ℂ A B = Arrow ℂ A B
|
||||
|
||||
module _ {ℓ ℓ' : Level} {ℂ : Category ℓ ℓ'} where
|
||||
HomFromArrow : (A : ℂ .Object) → {B B' : ℂ .Object} → (g : ℂ .Arrow B B')
|
||||
→ Hom ℂ A B → Hom ℂ A B'
|
||||
HomFromArrow _A = ℂ ._∘_
|
||||
|
||||
module _ {ℓ ℓ'} (ℂ : Category ℓ ℓ') {{hasProducts : HasProducts ℂ}} where
|
||||
open HasProducts hasProducts
|
||||
open Product hiding (obj)
|
||||
private
|
||||
_×p_ : (A B : ℂ .Object) → ℂ .Object
|
||||
_×p_ : (A B : Obj ℂ) → Obj ℂ
|
||||
_×p_ A B = Product.obj (product A B)
|
||||
|
||||
module _ (B C : ℂ .Category.Object) where
|
||||
IsExponential : (Cᴮ : ℂ .Object) → ℂ .Arrow (Cᴮ ×p B) C → Set (ℓ ⊔ ℓ')
|
||||
IsExponential Cᴮ eval = ∀ (A : ℂ .Object) (f : ℂ .Arrow (A ×p B) C)
|
||||
→ ∃![ f~ ] (ℂ [ eval ∘ parallelProduct f~ (ℂ .𝟙)] ≡ f)
|
||||
module _ (B C : Obj ℂ) where
|
||||
IsExponential : (Cᴮ : Obj ℂ) → ℂ [ Cᴮ ×p B , C ] → Set (ℓ ⊔ ℓ')
|
||||
IsExponential Cᴮ eval = ∀ (A : Obj ℂ) (f : ℂ [ A ×p B , C ])
|
||||
→ ∃![ f~ ] (ℂ [ eval ∘ parallelProduct f~ (Category.raw ℂ .𝟙)] ≡ f)
|
||||
|
||||
record Exponential : Set (ℓ ⊔ ℓ') where
|
||||
field
|
||||
-- obj ≡ Cᴮ
|
||||
obj : ℂ .Object
|
||||
eval : ℂ .Arrow ( obj ×p B ) C
|
||||
obj : Obj ℂ
|
||||
eval : ℂ [ obj ×p B , C ]
|
||||
{{isExponential}} : IsExponential obj eval
|
||||
-- If I make this an instance-argument then the instance resolution
|
||||
-- algorithm goes into an infinite loop. Why?
|
||||
exponentialsHaveProducts : HasProducts ℂ
|
||||
exponentialsHaveProducts = hasProducts
|
||||
transpose : (A : ℂ .Object) → ℂ .Arrow (A ×p B) C → ℂ .Arrow A obj
|
||||
transpose : (A : Obj ℂ) → ℂ [ A ×p B , C ] → ℂ [ A , obj ]
|
||||
transpose A f = fst (isExponential A f)
|
||||
|
||||
record HasExponentials {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') {{_ : HasProducts ℂ}} : Set (ℓ ⊔ ℓ') where
|
||||
field
|
||||
exponent : (A B : ℂ .Object) → Exponential ℂ A B
|
||||
exponent : (A B : Obj ℂ) → Exponential ℂ A B
|
||||
|
||||
record CartesianClosed {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') : Set (ℓ ⊔ ℓ') where
|
||||
field
|
||||
|
|
@ -234,15 +242,15 @@ record CartesianClosed {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') : Set (ℓ
|
|||
module _ {ℓa ℓb : Level} (ℂ : Category ℓa ℓb) where
|
||||
unique = isContr
|
||||
|
||||
IsInitial : ℂ .Object → Set (ℓa ⊔ ℓb)
|
||||
IsInitial I = {X : ℂ .Object} → unique (ℂ .Arrow I X)
|
||||
IsInitial : Obj ℂ → Set (ℓa ⊔ ℓb)
|
||||
IsInitial I = {X : Obj ℂ} → unique (ℂ [ I , X ])
|
||||
|
||||
IsTerminal : ℂ .Object → Set (ℓa ⊔ ℓb)
|
||||
IsTerminal : Obj ℂ → Set (ℓa ⊔ ℓb)
|
||||
-- ∃![ ? ] ?
|
||||
IsTerminal T = {X : ℂ .Object} → unique (ℂ .Arrow X T)
|
||||
IsTerminal T = {X : Obj ℂ} → unique (ℂ [ X , T ])
|
||||
|
||||
Initial : Set (ℓa ⊔ ℓb)
|
||||
Initial = Σ (ℂ .Object) IsInitial
|
||||
Initial = Σ (Obj ℂ) IsInitial
|
||||
|
||||
Terminal : Set (ℓa ⊔ ℓb)
|
||||
Terminal = Σ (ℂ .Object) IsTerminal
|
||||
Terminal = Σ (Obj ℂ) IsTerminal
|
||||
|
|
|
|||
|
|
@ -10,33 +10,33 @@ open import Cat.Category as C
|
|||
module _ {ℓ ℓ' : Level} (ℂ : Category ℓ ℓ') where
|
||||
private
|
||||
open module ℂ = Category ℂ
|
||||
Obj = ℂ.Object
|
||||
|
||||
postulate
|
||||
Path : ( a b : Obj ) → Set ℓ'
|
||||
emptyPath : (o : Obj) → Path o o
|
||||
concatenate : {a b c : Obj} → Path b c → Path a b → Path a c
|
||||
Path : ( a b : Obj ℂ ) → Set ℓ'
|
||||
emptyPath : (o : Obj ℂ) → Path o o
|
||||
concatenate : {a b c : Obj ℂ} → 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
|
||||
module _ {A B C D : Obj ℂ} {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
|
||||
module _ {A B : Obj ℂ} {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 ℓ ℓ'
|
||||
Free = record
|
||||
{ Object = Obj
|
||||
RawFree : RawCategory ℓ ℓ'
|
||||
RawFree = record
|
||||
{ Object = Obj ℂ
|
||||
; Arrow = Path
|
||||
; 𝟙 = λ {o} → emptyPath o
|
||||
; _∘_ = λ {a b c} → concatenate {a} {b} {c}
|
||||
; isCategory = record
|
||||
}
|
||||
RawIsCategoryFree : IsCategory RawFree
|
||||
RawIsCategoryFree = record
|
||||
{ assoc = p-assoc
|
||||
; ident = ident-r , ident-l
|
||||
; arrow-is-set = {!!}
|
||||
; univalent = {!!}
|
||||
}
|
||||
}
|
||||
|
|
|
|||
|
|
@ -10,11 +10,11 @@ open Category hiding (_∘_)
|
|||
|
||||
module _ {ℓc ℓc' ℓd ℓd'} (ℂ : Category ℓc ℓc') (𝔻 : Category ℓd ℓd') where
|
||||
record IsFunctor
|
||||
(func* : ℂ .Object → 𝔻 .Object)
|
||||
(func→ : {A B : ℂ .Object} → ℂ [ A , B ] → 𝔻 [ func* A , func* B ])
|
||||
(func* : Obj ℂ → Obj 𝔻)
|
||||
(func→ : {A B : Obj ℂ} → ℂ [ A , B ] → 𝔻 [ func* A , func* B ])
|
||||
: Set (ℓc ⊔ ℓc' ⊔ ℓd ⊔ ℓd') where
|
||||
field
|
||||
ident : { c : ℂ .Object } → func→ (ℂ .𝟙 {c}) ≡ 𝔻 .𝟙 {func* c}
|
||||
ident : {c : Obj ℂ} → func→ (ℂ .𝟙 {c}) ≡ 𝔻 .𝟙 {func* 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
|
||||
|
|
|
|||
Loading…
Reference in a new issue