Theorem: CategoryTheory.Comonad.ForgetCreatesLimits'.conePoint_A
File: Mathlib/CategoryTheory/Monad/Limits.lean

Proof steps:
state_before: C : Type u₁
inst✝⁵ : Category.{v₁, u₁} C
D✝ : Type u₂
inst✝⁴ : Category.{v₂, u₂} D✝
J : Type u
inst✝³ : Category.{v, u} J
T : Comonad C
D : J ⥤ T.Coalgebra
c : Cone (D ⋙ T.forget)
t : IsLimit c
inst✝² : PreservesLimit (D ⋙ T.forget) T.toFunctor
inst✝¹ : PreservesLimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
j : J
⊢ (lambda c t ≫ T.ε.app c.pt) ≫ c.π.app j = 𝟙 c.pt ≫ c.π.app j
state_after: C : Type u₁
inst✝⁵ : Category.{v₁, u₁} C
D✝ : Type u₂
inst✝⁴ : Category.{v₂, u₂} D✝
J : Type u
inst✝³ : Category.{v, u} J
T : Comonad C
D : J ⥤ T.Coalgebra
c : Cone (D ⋙ T.forget)
t : IsLimit c
inst✝² : PreservesLimit (D ⋙ T.forget) T.toFunctor
inst✝¹ : PreservesLimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
j : J
⊢ c.π.app j ≫ (D.obj j).a ≫ T.ε.app (T.forget.obj (D.obj j)) = 𝟙 c.pt ≫ c.π.app j
tactic: rw [assoc, ← show _ = _ ≫ c.π.app j from T.ε.naturality _, ← assoc, commuting, assoc]
state_before: C : Type u₁
inst✝⁵ : Category.{v₁, u₁} C
D✝ : Type u₂
inst✝⁴ : Category.{v₂, u₂} D✝
J : Type u
inst✝³ : Category.{v, u} J
T : Comonad C
D : J ⥤ T.Coalgebra
c : Cone (D ⋙ T.forget)
t : IsLimit c
inst✝² : PreservesLimit (D ⋙ T.forget) T.toFunctor
inst✝¹ : PreservesLimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
j : J
⊢ c.π.app j ≫ (D.obj j).a ≫ T.ε.app (T.forget.obj (D.obj j)) = 𝟙 c.pt ≫ c.π.app j
state_after: no goals
tactic: simp [Coalgebra.counit (D.obj j)]
state_before: C : Type u₁
inst✝⁵ : Category.{v₁, u₁} C
D✝ : Type u₂
inst✝⁴ : Category.{v₂, u₂} D✝
J : Type u
inst✝³ : Category.{v, u} J
T : Comonad C
D : J ⥤ T.Coalgebra
c : Cone (D ⋙ T.forget)
t : IsLimit c
inst✝² : PreservesLimit (D ⋙ T.forget) T.toFunctor
inst✝¹ : PreservesLimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
⊢ lambda c t ≫ T.δ.app c.pt = lambda c t ≫ T.map (lambda c t)
state_after: C : Type u₁
inst✝⁵ : Category.{v₁, u₁} C
D✝ : Type u₂
inst✝⁴ : Category.{v₂, u₂} D✝
J : Type u
inst✝³ : Category.{v, u} J
T : Comonad C
D : J ⥤ T.Coalgebra
c : Cone (D ⋙ T.forget)
t : IsLimit c
inst✝² : PreservesLimit (D ⋙ T.forget) T.toFunctor
inst✝¹ : PreservesLimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
j : J
⊢ (lambda c t ≫ T.δ.app c.pt) ≫ (T.mapCone (T.mapCone c)).π.app j =
    (lambda c t ≫ T.map (lambda c t)) ≫ (T.mapCone (T.mapCone c)).π.app j
tactic: refine (isLimitOfPreserves _ (isLimitOfPreserves _ t)).hom_ext fun j => ?_
state_before: C : Type u₁
inst✝⁵ : Category.{v₁, u₁} C
D✝ : Type u₂
inst✝⁴ : Category.{v₂, u₂} D✝
J : Type u
inst✝³ : Category.{v, u} J
T : Comonad C
D : J ⥤ T.Coalgebra
c : Cone (D ⋙ T.forget)
t : IsLimit c
inst✝² : PreservesLimit (D ⋙ T.forget) T.toFunctor
inst✝¹ : PreservesLimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
j : J
⊢ (lambda c t ≫ T.δ.app c.pt) ≫ (T.mapCone (T.mapCone c)).π.app j =
    (lambda c t ≫ T.map (lambda c t)) ≫ (T.mapCone (T.mapCone c)).π.app j
state_after: C : Type u₁
inst✝⁵ : Category.{v₁, u₁} C
D✝ : Type u₂
inst✝⁴ : Category.{v₂, u₂} D✝
J : Type u
inst✝³ : Category.{v, u} J
T : Comonad C
D : J ⥤ T.Coalgebra
c : Cone (D ⋙ T.forget)
t : IsLimit c
inst✝² : PreservesLimit (D ⋙ T.forget) T.toFunctor
inst✝¹ : PreservesLimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
j : J
⊢ (c.π.app j ≫ (D.obj j).a) ≫ T.δ.app ((D ⋙ T.forget).obj j) = lambda c t ≫ T.map (c.π.app j) ≫ T.map (D.obj j).a
tactic: rw [Functor.mapCone_π_app, Functor.mapCone_π_app, assoc,
      ← show _ = _ ≫ T.map (T.map _) from T.δ.naturality _, assoc, ← Functor.map_comp, commuting,
      Functor.map_comp, ← assoc, commuting]
state_before: C : Type u₁
inst✝⁵ : Category.{v₁, u₁} C
D✝ : Type u₂
inst✝⁴ : Category.{v₂, u₂} D✝
J : Type u
inst✝³ : Category.{v, u} J
T : Comonad C
D : J ⥤ T.Coalgebra
c : Cone (D ⋙ T.forget)
t : IsLimit c
inst✝² : PreservesLimit (D ⋙ T.forget) T.toFunctor
inst✝¹ : PreservesLimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
j : J
⊢ (c.π.app j ≫ (D.obj j).a) ≫ T.δ.app ((D ⋙ T.forget).obj j) = lambda c t ≫ T.map (c.π.app j) ≫ T.map (D.obj j).a
state_after: C : Type u₁
inst✝⁵ : Category.{v₁, u₁} C
D✝ : Type u₂
inst✝⁴ : Category.{v₂, u₂} D✝
J : Type u
inst✝³ : Category.{v, u} J
T : Comonad C
D : J ⥤ T.Coalgebra
c : Cone (D ⋙ T.forget)
t : IsLimit c
inst✝² : PreservesLimit (D ⋙ T.forget) T.toFunctor
inst✝¹ : PreservesLimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
j : J
⊢ c.π.app j ≫ (D.obj j).a ≫ T.δ.app (D.obj j).A = lambda c t ≫ T.map (c.π.app j) ≫ T.map (D.obj j).a
tactic: simp only [Functor.comp_obj, forget_obj, Functor.const_obj_obj, assoc]
state_before: C : Type u₁
inst✝⁵ : Category.{v₁, u₁} C
D✝ : Type u₂
inst✝⁴ : Category.{v₂, u₂} D✝
J : Type u
inst✝³ : Category.{v, u} J
T : Comonad C
D : J ⥤ T.Coalgebra
c : Cone (D ⋙ T.forget)
t : IsLimit c
inst✝² : PreservesLimit (D ⋙ T.forget) T.toFunctor
inst✝¹ : PreservesLimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
j : J
⊢ c.π.app j ≫ (D.obj j).a ≫ T.δ.app (D.obj j).A = lambda c t ≫ T.map (c.π.app j) ≫ T.map (D.obj j).a
state_after: no goals
tactic: rw [(D.obj j).coassoc,  ← assoc, ← assoc, commuting]