Module: Mathlib.CategoryTheory.Sites.LeftExact

Goal state before:
pp: case e_a
C : Type u
inst✝¹² : Category.{v, u} C
J : GrothendieckTopology C
D : Type w
inst✝¹¹ : Category.{t, w} D
inst✝¹⁰ : ∀ (P : Cᵒᵖ ⥤ D) (X : C) (S : J.Cover X), HasMultiequalizer (S.index P)
inst✝⁹ : ∀ (X : C), HasColimitsOfShape (J.Cover X)ᵒᵖ D
FD : D → D → Type u_1
CD : D → Type t
inst✝⁸ : (X Y : D) → FunLike (FD X Y) (CD X) (CD Y)
inst✝⁷ : ConcreteCategory D FD
inst✝⁶ : ∀ (X : C), PreservesColimitsOfShape (J.Cover X)ᵒᵖ (forget D)
inst✝⁵ : ∀ (X : C), Small.{t, max u v} (J.Cover X)ᵒᵖ
K : Type s
inst✝⁴ : SmallCategory K
inst✝³ : FinCategory K
inst✝² : HasLimitsOfShape K D
inst✝¹ : PreservesLimitsOfShape K (forget D)
inst✝ : ReflectsLimitsOfShape K (forget D)
F : K ⥤ Cᵒᵖ ⥤ D
X : C
S : Cone (F ⋙ J.plusFunctor D ⋙ (evaluation Cᵒᵖ D).obj (op X))
k : K
j : (J.Cover (unop (op X)))ᵒᵖ
⊢ (J.diagramNatTrans (limit.π F k) X).app j ≫ colimit.ι (J.diagram (F.obj k) X) j =
    ((isLimitOfPreserves (J.diagramFunctor D X) (limit.isLimit F)).conePointUniqueUpToIso
              (limit.isLimit (F ⋙ J.diagramFunctor D X))).hom.app
        j ≫
      colimit.ι (limit (F ⋙ J.diagramFunctor D X)) j ≫
        (colimitLimitIso (F ⋙ J.diagramFunctor D X)).hom ≫
          (HasLimit.isoOfNatIso
                (NatIso.ofComponents (fun k ↦ colimitObjIsoColimitCompEvaluation (F ⋙ J.diagramFunctor D X).flip k)
                    ⋯).symm).inv ≫
            limit.π (F ⋙ J.plusFunctor D ⋙ (evaluation Cᵒᵖ D).obj (op X)) k

Tactic:
dsimp [IsLimit.conePointUniqueUpToIso, HasLimit.isoOfNatIso, IsLimit.map]

Goal state after:
case e_a
C : Type u
inst✝¹² : Category.{v, u} C
J : GrothendieckTopology C
D : Type w
inst✝¹¹ : Category.{t, w} D
inst✝¹⁰ : ∀ (P : Cᵒᵖ ⥤ D) (X : C) (S : J.Cover X), HasMultiequalizer (S.index P)
inst✝⁹ : ∀ (X : C), HasColimitsOfShape (J.Cover X)ᵒᵖ D
FD : D → D → Type u_1
CD : D → Type t
inst✝⁸ : (X Y : D) → FunLike (FD X Y) (CD X) (CD Y)
inst✝⁷ : ConcreteCategory D FD
inst✝⁶ : ∀ (X : C), PreservesColimitsOfShape (J.Cover X)ᵒᵖ (forget D)
inst✝⁵ : ∀ (X : C), Small.{t, max u v} (J.Cover X)ᵒᵖ
K : Type s
inst✝⁴ : SmallCategory K
inst✝³ : FinCategory K
inst✝² : HasLimitsOfShape K D
inst✝¹ : PreservesLimitsOfShape K (forget D)
inst✝ : ReflectsLimitsOfShape K (forget D)
F : K ⥤ Cᵒᵖ ⥤ D
X : C
S : Cone (F ⋙ J.plusFunctor D ⋙ (evaluation Cᵒᵖ D).obj (op X))
k : K
j : (J.Cover (unop (op X)))ᵒᵖ
⊢ Multiequalizer.lift ((unop j).index (F.obj k)) (multiequalizer ((unop j).index (limit F)))
        (fun x ↦ Multiequalizer.ι ((unop j).index (limit F)) x ≫ (limit.π F k).app (op x.Y)) ⋯ ≫
      colimit.ι (J.diagram (F.obj k) X) j =
    (limit.lift (F ⋙ J.diagramFunctor D X) ((J.diagramFunctor D X).mapCone (limit.cone F))).app j ≫
      colimit.ι (limit (F ⋙ J.diagramFunctor D X)) j ≫
        (colimitLimitIso (F ⋙ J.diagramFunctor D X)).hom ≫
          limit.lift (F ⋙ J.plusFunctor D ⋙ (evaluation Cᵒᵖ D).obj (op X))
              ((Cone.postcompose
                    (NatIso.ofComponents (fun k ↦ colimitObjIsoColimitCompEvaluation (F ⋙ J.diagramFunctor D X).flip k)
                        ⋯).hom).obj
                (limit.cone (colimit (F ⋙ J.diagramFunctor D X).flip))) ≫
            limit.π (F ⋙ J.plusFunctor D ⋙ (evaluation Cᵒᵖ D).obj (op X)) k