Theorem: CategoryTheory.Monad.ForgetCreatesColimits.liftedCoconeIsColimit_desc_f
File: Mathlib/CategoryTheory/Monad/Limits.lean

Proof steps:
state_before: C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J : Type u
inst✝² : Category.{v, u} J
D : J ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
j : J
⊢ (T.mapCocone c).ι.app j ≫ T.map (t.desc (T.forget.mapCocone s)) ≫ s.pt.a =
    (T.mapCocone c).ι.app j ≫ (liftedCocone c t).pt.a ≫ t.desc (T.forget.mapCocone s)
state_after: C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J : Type u
inst✝² : Category.{v, u} J
D : J ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
j : J
⊢ T.map (c.ι.app j) ≫ T.map (t.desc (T.forget.mapCocone s)) ≫ s.pt.a =
    T.map (c.ι.app j) ≫ lambda c t ≫ t.desc (T.forget.mapCocone s)
tactic: dsimp
state_before: C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J : Type u
inst✝² : Category.{v, u} J
D : J ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
j : J
⊢ T.map (c.ι.app j) ≫ T.map (t.desc (T.forget.mapCocone s)) ≫ s.pt.a =
    T.map (c.ι.app j) ≫ lambda c t ≫ t.desc (T.forget.mapCocone s)
state_after: C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J : Type u
inst✝² : Category.{v, u} J
D : J ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
j : J
⊢ T.map ((T.forget.mapCocone s).ι.app j) ≫ s.pt.a = (D.obj j).a ≫ (T.forget.mapCocone s).ι.app j
tactic: rw [← Functor.map_comp_assoc, ← Category.assoc, t.fac, commuting, Category.assoc, t.fac]
state_before: C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J : Type u
inst✝² : Category.{v, u} J
D : J ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
j : J
⊢ T.map ((T.forget.mapCocone s).ι.app j) ≫ s.pt.a = (D.obj j).a ≫ (T.forget.mapCocone s).ι.app j
state_after: no goals
tactic: apply Algebra.Hom.h
state_before: C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J✝ : Type u
inst✝² : Category.{v, u} J✝
D : J✝ ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
m : (liftedCocone c t).pt ⟶ s.pt
J : ∀ (j : J✝), (liftedCocone c t).ι.app j ≫ m = s.ι.app j
⊢ m = (fun s => { f := t.desc (T.forget.mapCocone s), h := ⋯ }) s
state_after: case h
C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J✝ : Type u
inst✝² : Category.{v, u} J✝
D : J✝ ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
m : (liftedCocone c t).pt ⟶ s.pt
J : ∀ (j : J✝), (liftedCocone c t).ι.app j ≫ m = s.ι.app j
⊢ m.f = ((fun s => { f := t.desc (T.forget.mapCocone s), h := ⋯ }) s).f
tactic: ext1
state_before: case h
C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J✝ : Type u
inst✝² : Category.{v, u} J✝
D : J✝ ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
m : (liftedCocone c t).pt ⟶ s.pt
J : ∀ (j : J✝), (liftedCocone c t).ι.app j ≫ m = s.ι.app j
⊢ m.f = ((fun s => { f := t.desc (T.forget.mapCocone s), h := ⋯ }) s).f
state_after: case h
C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J✝ : Type u
inst✝² : Category.{v, u} J✝
D : J✝ ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
m : (liftedCocone c t).pt ⟶ s.pt
J : ∀ (j : J✝), (liftedCocone c t).ι.app j ≫ m = s.ι.app j
⊢ ∀ (j : J✝), c.ι.app j ≫ m.f = c.ι.app j ≫ ((fun s => { f := t.desc (T.forget.mapCocone s), h := ⋯ }) s).f
tactic: apply t.hom_ext
state_before: case h
C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J✝ : Type u
inst✝² : Category.{v, u} J✝
D : J✝ ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
m : (liftedCocone c t).pt ⟶ s.pt
J : ∀ (j : J✝), (liftedCocone c t).ι.app j ≫ m = s.ι.app j
⊢ ∀ (j : J✝), c.ι.app j ≫ m.f = c.ι.app j ≫ ((fun s => { f := t.desc (T.forget.mapCocone s), h := ⋯ }) s).f
state_after: case h
C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J✝ : Type u
inst✝² : Category.{v, u} J✝
D : J✝ ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
m : (liftedCocone c t).pt ⟶ s.pt
J : ∀ (j : J✝), (liftedCocone c t).ι.app j ≫ m = s.ι.app j
j : J✝
⊢ c.ι.app j ≫ m.f = c.ι.app j ≫ ((fun s => { f := t.desc (T.forget.mapCocone s), h := ⋯ }) s).f
tactic: intro j
state_before: case h
C : Type u₁
inst✝³ : Category.{v₁, u₁} C
T : Monad C
J✝ : Type u
inst✝² : Category.{v, u} J✝
D : J✝ ⥤ T.Algebra
c : Cocone (D ⋙ T.forget)
t : IsColimit c
inst✝¹ : PreservesColimit (D ⋙ T.forget) T.toFunctor
inst✝ : PreservesColimit ((D ⋙ T.forget) ⋙ T.toFunctor) T.toFunctor
s : Cocone D
m : (liftedCocone c t).pt ⟶ s.pt
J : ∀ (j : J✝), (liftedCocone c t).ι.app j ≫ m = s.ι.app j
j : J✝
⊢ c.ι.app j ≫ m.f = c.ι.app j ≫ ((fun s => { f := t.desc (T.forget.mapCocone s), h := ⋯ }) s).f
state_after: no goals
tactic: simpa using congr_arg Algebra.Hom.f (J j)