Worked on strength of delay

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Leon Vatthauer 2023-09-21 22:34:38 +02:00
parent 6ce2526b6a
commit 7c5dccc0ab
Signed by: leonv
SSH key fingerprint: SHA256:G4+ddwoZmhLPRB1agvXzZMXIzkVJ36dUYZXf5NxT+u8
2 changed files with 205 additions and 97 deletions

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@ -9,6 +9,8 @@ open import Categories.Category.Distributive using (Distributive)
open import Categories.Category.Cartesian using (Cartesian)
open import Categories.Category.BinaryProducts using (BinaryProducts)
open import Categories.Category.Cartesian.Bundle using (CartesianCategory)
open import Categories.Category.Cartesian.Monoidal
open import Categories.Category.Monoidal
open import Categories.Category.Cocartesian using (Cocartesian)
open import Categories.Object.NaturalNumbers.Parametrized using (ParametrizedNNO)
open import Categories.Object.Exponential using (Exponential)
@ -43,6 +45,8 @@ module Category.Instance.AmbientCategory where
open Extensive extensive public
open Cocartesian cocartesian renaming (+-unique to []-unique) public
open Cartesian cartesian public
monoidal : Monoidal C
monoidal = CartesianMonoidal.monoidal cartesian
-- open Terminal terminal public
-- Don't open the terminal object, because we are interested in many different terminal objects stemming from multiple categories
open BinaryProducts products renaming (η to ⁂-η; g-η to ⁂-g-η; unique to ⟨⟩-unique; unique to ⟨⟩-unique) public
@ -52,6 +56,15 @@ module Category.Instance.AmbientCategory where
distributive : Distributive C
distributive = Extensive×Cartesian⇒Distributive C extensive cartesian
open Distributive distributive hiding (cartesian; cocartesian) public
open M' C
distributeˡ⁻¹ : ∀ {A B C : Obj} → A × (B + C) ⇒ A × B + A × C
distributeˡ⁻¹ = IsIso.inv isIsoˡ
distributeʳ⁻¹ : ∀ {A B C : Obj} → (B + C) × A ⇒ B × A + C × A
distributeʳ⁻¹ = IsIso.inv isIsoʳ
module M = M'
module MR = MR'

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@ -7,10 +7,12 @@ open import Categories.Object.Terminal
open import Categories.Category.Construction.F-Coalgebras
open import Categories.Category.Construction.F-Algebras
open import Categories.Functor.Coalgebra
open import Categories.Functor
open import Categories.Functor renaming (id to idF)
open import Categories.Functor.Algebra
open import Categories.Monad.Construction.Kleisli
open import Categories.Monad.Strong
open import Categories.Category.Construction.F-Coalgebras
open import Categories.NaturalTransformation
open import Category.Instance.AmbientCategory using (Ambient)
```
-->
@ -121,32 +123,20 @@ and second that `extend f` is the unique morphism satisfying the commutative dia
D₀ : Obj → Obj
D₀ X = DX {X}
kleisli : KleisliTriple C
kleisli = record
{ F₀ = D₀
; unit = now
; extend = extend
; identityʳ = identityʳ'
; identityˡ = identityˡ'
; assoc = assoc'
; sym-assoc = sym assoc'
; extend-≈ = extend-≈'
}
where
open Terminal
module _ {X Y : Obj} (f : X ⇒ D₀ Y) where
open Terminal
alg : F-Coalgebra (Y +-)
alg = record { A = D₀ X + D₀ Y ; α = [ [ [ i₁ , i₂ ∘ i₂ ] ∘ (out ∘ f) , i₂ ∘ i₁ ] ∘ out , (idC +₁ i₂) ∘ out ] }
extend : D₀ X ⇒ D₀ Y
extend = u (! (coalgebras Y) {A = alg}) ∘ i₁ {B = D₀ Y}
extend' : D₀ X ⇒ D₀ Y
extend' = u (! (coalgebras Y) {A = alg}) ∘ i₁ {B = D₀ Y}
!∘i₂ : u (! (coalgebras Y) {A = alg}) ∘ i₂ ≈ idC
!∘i₂ = -id (coalgebras Y) (F-Coalgebras (Y +-) [ ! (coalgebras Y) ∘ record { f = i₂ ; commutes = inject₂ } ] )
extendlaw : out ∘ extend ≈ [ out ∘ f , i₂ ∘ extend ] ∘ out
extendlaw : out ∘ extend' ≈ [ out ∘ f , i₂ ∘ extend' ] ∘ out
extendlaw = begin
out ∘ extend ≈⟨ pullˡ (commutes (! (coalgebras Y) {A = alg})) ⟩
out ∘ extend' ≈⟨ pullˡ (commutes (! (coalgebras Y) {A = alg})) ⟩
((idC +₁ (u (! (coalgebras Y)))) ∘ α alg) ∘ i₁ ≈⟨ pullʳ inject₁ ⟩
(idC +₁ (u (! (coalgebras Y)))) ∘ [ [ i₁ , i₂ ∘ i₂ ]
∘ (out ∘ f) , i₂ ∘ i₁ ] ∘ out ≈⟨ pullˡ ∘[] ⟩
@ -161,11 +151,11 @@ and second that `extend f` is the unique morphism satisfying the commutative dia
, (i₂ ∘ (u (! (coalgebras Y)))) ∘ i₁ ] ∘ out ≈⟨ ([]-cong₂
(elimˡ (([]-cong₂ identityʳ (cancelʳ !∘i₂)) ○ +-η))
assoc) ⟩∘⟨refl ⟩
[ out ∘ f , i₂ ∘ extend ] ∘ out ∎
[ out ∘ f , i₂ ∘ extend' ] ∘ out ∎
extend-unique : (g : D₀ X ⇒ D₀ Y) → (out ∘ g ≈ [ out ∘ f , i₂ ∘ g ] ∘ out) → extend ≈ g
extend-unique g g-commutes = begin
extend ≈⟨ (!-unique (coalgebras Y) (record { f = [ g , idC ] ; commutes = begin
extend'-unique : (g : D₀ X ⇒ D₀ Y) → (out ∘ g ≈ [ out ∘ f , i₂ ∘ g ] ∘ out) → extend' ≈ g
extend'-unique g g-commutes = begin
extend' ≈⟨ (!-unique (coalgebras Y) (record { f = [ g , idC ] ; commutes = begin
out ∘ [ g , idC ] ≈⟨ ∘[] ⟩
[ out ∘ g , out ∘ idC ] ≈⟨ []-cong₂ g-commutes identityʳ ⟩
[ [ out ∘ f , i₂ ∘ g ] ∘ out , out ] ≈˘⟨ []-cong₂
@ -208,6 +198,20 @@ and second that `extend f` is the unique morphism satisfying the commutative dia
[ g , idC ] ∘ i₁ ≈⟨ inject₁ ⟩
g ∎
kleisli : KleisliTriple C
kleisli = record
{ F₀ = D₀
; unit = now
; extend = extend'
; identityʳ = identityʳ'
; identityˡ = identityˡ'
; assoc = assoc'
; sym-assoc = sym assoc'
; extend-≈ = extend-≈'
}
where
open Terminal
αf≈αg : ∀ {X Y} {f g : X ⇒ D₀ Y} → f ≈ g → α (alg f) ≈ α (alg g)
αf≈αg {X} {Y} {f} {g} eq = []-cong₂ ([]-cong₂ (refl⟩∘⟨ refl⟩∘⟨ eq) refl ⟩∘⟨refl) refl
@ -230,18 +234,18 @@ and second that `extend f` is the unique morphism satisfying the commutative dia
}
where open Functor (Y +-) using (identity)
identityʳ' : ∀ {X Y : Obj} {f : X ⇒ D₀ Y} → extend f ∘ now {X} ≈ f
identityʳ' : ∀ {X Y : Obj} {f : X ⇒ D₀ Y} → extend' f ∘ now {X} ≈ f
identityʳ' {X} {Y} {f} = begin
extend f ∘ now ≈⟨ insertˡ (_≅_.isoˡ out-≅) ⟩∘⟨refl ⟩
(out⁻¹ ∘ out ∘ extend f) ∘ now ≈⟨ (refl⟩∘⟨ (extendlaw f)) ⟩∘⟨refl ⟩
(out⁻¹ ∘ [ out ∘ f , i₂ ∘ extend f ] ∘ out) ∘ now ≈⟨ pullʳ (pullʳ unitlaw) ⟩
out⁻¹ ∘ [ out ∘ f , i₂ ∘ extend f ] ∘ i₁ ≈⟨ refl⟩∘⟨ inject₁ ⟩
extend' f ∘ now ≈⟨ insertˡ (_≅_.isoˡ out-≅) ⟩∘⟨refl ⟩
(out⁻¹ ∘ out ∘ extend' f) ∘ now ≈⟨ (refl⟩∘⟨ (extendlaw f)) ⟩∘⟨refl ⟩
(out⁻¹ ∘ [ out ∘ f , i₂ ∘ extend' f ] ∘ out) ∘ now ≈⟨ pullʳ (pullʳ unitlaw) ⟩
out⁻¹ ∘ [ out ∘ f , i₂ ∘ extend' f ] ∘ i₁ ≈⟨ refl⟩∘⟨ inject₁ ⟩
out⁻¹ ∘ out ∘ f ≈⟨ cancelˡ (_≅_.isoˡ out-≅) ⟩
f ∎
identityˡ' : ∀ {X} → extend now ≈ idC
identityˡ' {X} = Terminal.-id (coalgebras X) (record { f = extend now ; commutes = begin
out ∘ extend now ≈⟨ pullˡ ((commutes (! (coalgebras X) {A = alg now}))) ⟩
identityˡ' : ∀ {X} → extend' now ≈ idC
identityˡ' {X} = Terminal.-id (coalgebras X) (record { f = extend' now ; commutes = begin
out ∘ extend' now ≈⟨ pullˡ ((commutes (! (coalgebras X) {A = alg now}))) ⟩
((idC +₁ (u (! (coalgebras X) {A = alg now}))) ∘ α (alg now)) ∘ i₁ ≈⟨ pullʳ inject₁ ⟩
(idC +₁ (u (! (coalgebras X) {A = alg now})))
∘ [ [ i₁ , i₂ ∘ i₂ ] ∘ (out ∘ now) , i₂ ∘ i₁ ] ∘ out ≈⟨ refl⟩∘⟨ []-cong₂ ((refl⟩∘⟨ unitlaw) ○ inject₁) refl ⟩∘⟨refl ⟩
@ -249,21 +253,21 @@ and second that `extend f` is the unique morphism satisfying the commutative dia
[ (idC +₁ (u (! (coalgebras X) {A = alg now}))) ∘ i₁
, (idC +₁ (u (! (coalgebras X) {A = alg now}))) ∘ i₂ ∘ i₁ ] ∘ out ≈⟨ []-cong₂ +₁∘i₁ (pullˡ +₁∘i₂) ⟩∘⟨refl ⟩
[ i₁ ∘ idC , (i₂ ∘ (u (! (coalgebras X) {A = alg now}))) ∘ i₁ ] ∘ out ≈⟨ []-cong₂ refl assoc ⟩∘⟨refl ⟩
[ i₁ ∘ idC , i₂ ∘ (extend now) ] ∘ out ≈˘⟨ []∘+₁ ⟩∘⟨refl ⟩
([ i₁ , i₂ ] ∘ (idC +₁ extend now)) ∘ out ≈⟨ elimˡ +-η ⟩∘⟨refl ⟩
(idC +₁ extend now) ∘ out ∎ })
[ i₁ ∘ idC , i₂ ∘ (extend' now) ] ∘ out ≈˘⟨ []∘+₁ ⟩∘⟨refl ⟩
([ i₁ , i₂ ] ∘ (idC +₁ extend' now)) ∘ out ≈⟨ elimˡ +-η ⟩∘⟨refl ⟩
(idC +₁ extend' now) ∘ out ∎ })
assoc' : ∀ {X Y Z : Obj} {g : X ⇒ D₀ Y} {h : Y ⇒ D₀ Z} → extend (extend h ∘ g) ≈ extend h ∘ extend g
assoc' {X} {Y} {Z} {g} {h} = extend-unique (extend h ∘ g) (extend h ∘ extend g) (begin
out ∘ extend h ∘ extend g ≈⟨ pullˡ (extendlaw h) ⟩
([ out ∘ h , i₂ ∘ extend h ] ∘ out) ∘ extend g ≈⟨ pullʳ (extendlaw g) ⟩
[ out ∘ h , i₂ ∘ extend h ] ∘ [ out ∘ g , i₂ ∘ extend g ] ∘ out ≈⟨ pullˡ ∘[] ⟩
[ [ out ∘ h , i₂ ∘ extend h ] ∘ out ∘ g
, [ out ∘ h , i₂ ∘ extend h ] ∘ i₂ ∘ extend g ] ∘ out ≈⟨ []-cong₂ (pullˡ (⟺ (extendlaw h))) (pullˡ inject₂) ⟩∘⟨refl ⟩
[ (out ∘ extend h) ∘ g , (i₂ ∘ extend h) ∘ extend g ] ∘ out ≈⟨ ([]-cong₂ assoc assoc) ⟩∘⟨refl ⟩
[ out ∘ extend h ∘ g , i₂ ∘ extend h ∘ extend g ] ∘ out ∎)
assoc' : ∀ {X Y Z : Obj} {g : X ⇒ D₀ Y} {h : Y ⇒ D₀ Z} → extend' (extend' h ∘ g) ≈ extend' h ∘ extend' g
assoc' {X} {Y} {Z} {g} {h} = extend'-unique (extend' h ∘ g) (extend' h ∘ extend' g) (begin
out ∘ extend' h ∘ extend' g ≈⟨ pullˡ (extendlaw h) ⟩
([ out ∘ h , i₂ ∘ extend' h ] ∘ out) ∘ extend' g ≈⟨ pullʳ (extendlaw g) ⟩
[ out ∘ h , i₂ ∘ extend' h ] ∘ [ out ∘ g , i₂ ∘ extend' g ] ∘ out ≈⟨ pullˡ ∘[] ⟩
[ [ out ∘ h , i₂ ∘ extend' h ] ∘ out ∘ g
, [ out ∘ h , i₂ ∘ extend' h ] ∘ i₂ ∘ extend' g ] ∘ out ≈⟨ []-cong₂ (pullˡ (⟺ (extendlaw h))) (pullˡ inject₂) ⟩∘⟨refl ⟩
[ (out ∘ extend' h) ∘ g , (i₂ ∘ extend' h) ∘ extend' g ] ∘ out ≈⟨ ([]-cong₂ assoc assoc) ⟩∘⟨refl ⟩
[ out ∘ extend' h ∘ g , i₂ ∘ extend' h ∘ extend' g ] ∘ out ∎)
extend-≈' : ∀ {X} {Y} {f g : X ⇒ D₀ Y} → f ≈ g → extend f ≈ extend g
extend-≈' : ∀ {X} {Y} {f g : X ⇒ D₀ Y} → f ≈ g → extend' f ≈ extend' g
extend-≈' {X} {Y} {f} {g} eq = begin
u (! (coalgebras Y) {A = alg f }) ∘ i₁ {B = D₀ Y} ≈⟨ (!-unique (coalgebras Y) (record { f = (u (! (coalgebras Y) {A = alg g }) ∘ idC) ; commutes = begin
α ( (coalgebras Y)) ∘ u (! (coalgebras Y)) ∘ idC ≈⟨ refl⟩∘⟨ identityʳ ⟩
@ -272,7 +276,7 @@ and second that `extend f` is the unique morphism satisfying the commutative dia
(idC +₁ u (! (coalgebras Y)) ∘ idC) ∘ α (alg f) ∎ }))
⟩∘⟨refl ⟩
(u (! (coalgebras Y) {A = alg g }) ∘ idC) ∘ i₁ {B = D₀ Y} ≈⟨ identityʳ ⟩∘⟨refl ⟩
extend g ∎
extend' g ∎
monad : Monad C
monad = Kleisli⇒Monad C kleisli
@ -281,3 +285,94 @@ and second that `extend f` is the unique morphism satisfying the commutative dia
functor : Endofunctor C
functor = Monad.F monad
```
Next we will show that the delay monad is strong, by giving a natural transformation `strengthen : X × DY ⇒ D (X × Y)
```agda
module _ where
open Functor
open import Categories.Category.Monoidal.Core
open Monoidal monoidal
open import Categories.Monad.Relative using () renaming (Monad to RMonad)
open RMonad kleisli using (extend)
open import Categories.Category.Product renaming (Product to CProduct; _⁂_ to _×C_)
strength : Strength monoidal monad
strength = record
{ strengthen = ntHelper (record
{ η = τ
; commute = commute' })
; identityˡ = λ {X} → begin
extend (now ∘ π₂) ∘ τ _ ≈⟨ introˡ (_≅_.isoˡ out-≅) ⟩
(out⁻¹ ∘ out) ∘ extend (now ∘ π₂) ∘ τ _ ≈⟨ pullʳ (pullˡ (extendlaw (now ∘ π₂))) ⟩
out⁻¹ ∘ ([ out ∘ now ∘ π₂ , i₂ ∘ extend (now ∘ π₂)] ∘ out) ∘ τ _ ≈⟨ refl⟩∘⟨ (pullʳ (τ-law (Terminal. terminal , X))) ⟩
out⁻¹ ∘ [ out ∘ now ∘ π₂ , i₂ ∘ extend (now ∘ π₂)] ∘ (idC +₁ τ _) ∘ distributeˡ⁻¹ ∘ (idC ⁂ out) ≈⟨ {! refl⟩∘⟨_ !} ⟩
{! !} ≈⟨ {! !} ⟩
{! !} ≈⟨ {! !} ⟩
{! !} ≈⟨ {! !} ⟩
{! !} ≈⟨ {! !} ⟩
-- TODO extend and τ are both final coalgebras, maybe use this?
π₂ ∎
; η-comm = {! !}
; μ-η-comm = {! !}
; strength-assoc = {! !}
}
where
open import Agda.Builtin.Sigma
module _ (P : Category.Obj (CProduct C C)) where
X = fst P
Y = snd P
open Terminal (coalgebras (X × Y))
τ : X × D₀ Y ⇒ D₀ (X × Y)
τ = u (! {A = record { A = X × D₀ Y ; α = distributeˡ⁻¹ ∘ (idC ⁂ out) }})
τ-law : out ∘ τ ≈ (idC +₁ τ) ∘ distributeˡ⁻¹ ∘ (idC ⁂ out)
τ-law = commutes (! {A = record { A = X × D₀ Y ; α = distributeˡ⁻¹ ∘ (idC ⁂ out) }})
τ-unique : (t : X × D₀ Y ⇒ D₀ (X × Y)) → (out ∘ t ≈ (idC +₁ t) ∘ distributeˡ⁻¹ ∘ (idC ⁂ out)) → t ≈ τ
τ-unique t t-commutes = sym (!-unique (record { f = t ; commutes = t-commutes }))
commute' : ∀ {P₁ : Category.Obj (CProduct C C)} {P₂ : Category.Obj (CProduct C C)} (fg : _[_,_] (CProduct C C) P₁ P₂)
→ τ P₂ ∘ ((fst fg) ⁂ extend (now ∘ (snd fg))) ≈ extend (now ∘ ((fst fg) ⁂ (snd fg))) ∘ τ P₁
commute' {(U , V)} {(W , X)} (f , g) = begin
τ _ ∘ (f ⁂ extend (now ∘ g)) ≈⟨ sym (!-unique (record { f = τ _ ∘ (f ⁂ extend (now ∘ g)) ; commutes = begin
out ∘ τ (W , X) ∘ (f ⁂ extend (now ∘ g)) ≈⟨ pullˡ (τ-law (W , X)) ⟩
((idC +₁ τ (W , X)) ∘ distributeˡ⁻¹ ∘ (idC ⁂ out)) ∘ (f ⁂ extend (now ∘ g)) ≈⟨ pullʳ (pullʳ ⁂∘⁂) ⟩
(idC +₁ τ (W , X)) ∘ distributeˡ⁻¹ ∘ (idC ∘ f ⁂ out ∘ extend (now ∘ g)) ≈⟨ refl⟩∘⟨ (refl⟩∘⟨ (⁂-cong₂ identityˡ (extendlaw (now ∘ g)))) ⟩
(idC +₁ τ (W , X)) ∘ distributeˡ⁻¹ ∘ (f ⁂ [ out ∘ now ∘ g , i₂ ∘ extend (now ∘ g) ] ∘ out) ≈⟨ refl⟩∘⟨ (refl⟩∘⟨ (⁂-cong₂ refl (([]-cong₂ (pullˡ unitlaw) refl) ⟩∘⟨refl))) ⟩
(idC +₁ τ (W , X)) ∘ distributeˡ⁻¹ ∘ (f ⁂ [ i₁ ∘ g , i₂ ∘ extend (now ∘ g) ] ∘ out) ≈⟨ refl⟩∘⟨ (refl⟩∘⟨ (⁂-cong₂ (sym identityʳ) refl)) ⟩
(idC +₁ τ (W , X)) ∘ distributeˡ⁻¹ ∘ (f ∘ idC ⁂ (g +₁ extend (now ∘ g)) ∘ out) ≈⟨ sym (pullʳ (pullʳ ⁂∘⁂)) ⟩
((idC +₁ τ (W , X)) ∘ distributeˡ⁻¹ ∘ (f ⁂ (g +₁ extend (now ∘ g)))) ∘ (idC ⁂ out) ≈⟨ (refl⟩∘⟨ (sym (distribute₁ f g (extend (now ∘ g))))) ⟩∘⟨refl ⟩
((idC +₁ τ (W , X)) ∘ ((f ⁂ g) +₁ (f ⁂ extend (now ∘ g))) ∘ distributeˡ⁻¹) ∘ (idC ⁂ out) ≈⟨ (pullˡ +₁∘+₁) ⟩∘⟨refl ⟩
((idC ∘ (f ⁂ g) +₁ τ (W , X) ∘ (f ⁂ extend (now ∘ g))) ∘ distributeˡ⁻¹) ∘ (idC ⁂ out) ≈⟨ sym (((+₁-cong₂ refl identityʳ) ⟩∘⟨refl) ⟩∘⟨refl) ⟩
((idC ∘ (f ⁂ g) +₁ (τ (W , X) ∘ (f ⁂ extend (now ∘ g))) ∘ idC) ∘ distributeˡ⁻¹) ∘ (idC ⁂ out) ≈⟨ sym (pullˡ (pullˡ +₁∘+₁)) ⟩
(idC +₁ (τ (W , X) ∘ (f ⁂ extend (now ∘ g)))) ∘ ((f ⁂ g +₁ idC) ∘ distributeˡ⁻¹) ∘ (idC ⁂ out) ∎ })) ⟩
u ! ≈⟨ !-unique (record { f = extend (now ∘ (f ⁂ g)) ∘ τ _ ; commutes = begin
out ∘ extend (now ∘ (f ⁂ g)) ∘ τ _ ≈⟨ pullˡ (extendlaw (now ∘ (f ⁂ g))) ⟩
([ out ∘ now ∘ (f ⁂ g) , i₂ ∘ extend (now ∘ (f ⁂ g)) ] ∘ out) ∘ τ (U , V) ≈⟨ (([]-cong₂ (pullˡ unitlaw) refl) ⟩∘⟨refl) ⟩∘⟨refl ⟩
([ i₁ ∘ (f ⁂ g) , i₂ ∘ extend (now ∘ (f ⁂ g)) ] ∘ out) ∘ τ (U , V) ≈⟨ pullʳ (τ-law (U , V)) ⟩
((f ⁂ g) +₁ (extend (now ∘ (f ⁂ g)))) ∘ (idC +₁ τ _) ∘ distributeˡ⁻¹ ∘ (idC ⁂ out) ≈⟨ sym-assoc ○ sym-assoc ⟩
((((f ⁂ g) +₁ (extend (now ∘ (f ⁂ g)))) ∘ (idC +₁ τ _)) ∘ distributeˡ⁻¹) ∘ (idC ⁂ out) ≈⟨ (+₁∘+₁ ⟩∘⟨refl) ⟩∘⟨refl ⟩
((((f ⁂ g) ∘ idC) +₁ (extend (now ∘ (f ⁂ g)) ∘ τ (U , V))) ∘ distributeˡ⁻¹) ∘ (idC ⁂ out) ≈⟨ sym (((+₁-cong₂ id-comm-sym identityʳ) ⟩∘⟨refl) ⟩∘⟨refl) ⟩
(((idC ∘ (f ⁂ g)) +₁ ((extend (now ∘ (f ⁂ g)) ∘ τ (U , V)) ∘ idC)) ∘ distributeˡ⁻¹) ∘ (idC ⁂ out) ≈⟨ sym (pullˡ (pullˡ +₁∘+₁)) ⟩
(idC +₁ (extend (now ∘ (f ⁂ g)) ∘ τ (U , V))) ∘ (((f ⁂ g) +₁ idC) ∘ distributeˡ⁻¹) ∘ (idC ⁂ out) ∎ }) ⟩
extend (now ∘ (f ⁂ g)) ∘ τ _ ∎
where
open Terminal (coalgebras (W × X))
alg' : F-Coalgebra ((W × X) +-)
alg' = record { A = U × D₀ V ; α = ((f ⁂ g) +₁ idC) ∘ distributeˡ⁻¹ ∘ (idC ⁂ out) }
distribute₁ : ∀ {X Y Z U V W} (f : X ⇒ U) (g : Y ⇒ V) (h : Z ⇒ W) → ((f ⁂ g) +₁ (f ⁂ h)) ∘ distributeˡ⁻¹ ≈ distributeˡ⁻¹ ∘ (f ⁂ (g +₁ h))
distribute₁ f g h = begin
((f ⁂ g) +₁ (f ⁂ h)) ∘ distributeˡ⁻¹ ≈⟨ introˡ (IsIso.isoˡ isIsoˡ) ⟩
(distributeˡ⁻¹ ∘ distributeˡ) ∘ ((f ⁂ g) +₁ (f ⁂ h)) ∘ distributeˡ⁻¹ ≈⟨ pullˡ (pullʳ []∘+₁) ⟩
(distributeˡ⁻¹ ∘ [(idC ⁂ i₁) ∘ (f ⁂ g) , (idC ⁂ i₂) ∘ (f ⁂ h)]) ∘ distributeˡ⁻¹ ≈⟨ (refl⟩∘⟨ ([]-cong₂ ⁂∘⁂ ⁂∘⁂)) ⟩∘⟨refl ⟩
(distributeˡ⁻¹ ∘ [ idC ∘ f ⁂ i₁ ∘ g , idC ∘ f ⁂ i₂ ∘ h ]) ∘ distributeˡ⁻¹ ≈⟨ sym ((refl⟩∘⟨ ([]-cong₂ (⁂-cong₂ id-comm +₁∘i₁) (⁂-cong₂ id-comm +₁∘i₂))) ⟩∘⟨refl) ⟩
(distributeˡ⁻¹ ∘ [ f ∘ idC ⁂ (g +₁ h) ∘ i₁ , f ∘ idC ⁂ (g +₁ h) ∘ i₂ ]) ∘ distributeˡ⁻¹ ≈˘⟨ (refl⟩∘⟨ ([]-cong₂ ⁂∘⁂ ⁂∘⁂)) ⟩∘⟨refl ⟩
(distributeˡ⁻¹ ∘ [ ((f ⁂ (g +₁ h)) ∘ (idC ⁂ i₁)) , ((f ⁂ (g +₁ h)) ∘ (idC ⁂ i₂)) ]) ∘ distributeˡ⁻¹ ≈⟨ sym (pullˡ (pullʳ ∘[])) ⟩
(distributeˡ⁻¹ ∘ (f ⁂ (g +₁ h))) ∘ distributeˡ ∘ distributeˡ⁻¹ ≈⟨ sym (introʳ (IsIso.isoʳ isIsoˡ)) ⟩
distributeˡ⁻¹ ∘ (f ⁂ (g +₁ h)) ∎
-- ⁂ ○ ˡ
strongMonad : StrongMonad monoidal
strongMonad = record { M = monad ; strength = strength }
```