Module: Mathlib.Algebra.Category.ModuleCat.Presheaf.Sheafify

Goal state before:
pp: case refine_1
C : Type u₁
inst✝⁴ : Category.{v₁, u₁} C
J : GrothendieckTopology C
R₀ : Cᵒᵖ ⥤ RingCat
R : Sheaf J RingCat
α : R₀ ⟶ R.obj
inst✝³ : Presheaf.IsLocallyInjective J α
inst✝² : Presheaf.IsLocallySurjective J α
M₀ : PresheafOfModules R₀
A : Sheaf J AddCommGrpCat
φ : M₀.presheaf ⟶ A.obj
inst✝¹ : Presheaf.IsLocallyInjective J φ
inst✝ : Presheaf.IsLocallySurjective J φ
X Y✝ : Cᵒᵖ
π : X ⟶ Y✝
r r' : ↑(R.obj.obj X)
m m' : ↑(A.obj.obj X)
S : Sieve (Opposite.unop X)
hS : S ∈ J (Opposite.unop X)
r₀ : Presieve.FamilyOfElements (R₀ ⋙ forget RingCat) S.arrows
m₀ : Presieve.FamilyOfElements (M₀.presheaf ⋙ forget Ab) S.arrows
hr₀ : (r₀.map (whiskerRight α (forget RingCat))).IsAmalgamation r
hm₀ : (m₀.map (whiskerRight φ (forget Ab))).IsAmalgamation m
a : ↑(A.obj.obj X)
ha : ((r₀.smul m₀).map (whiskerRight φ (forget Ab))).IsAmalgamation a
Y : Cᵒᵖ
f : X ⟶ Y
a₀ : ↑(R₀.obj Y)
ha₀ : (ConcreteCategory.hom (α.app Y)) a₀ = (ConcreteCategory.hom (R.obj.map f)) r
b₀ : ↑(M₀.obj Y)
hb₀ : (ConcreteCategory.hom (φ.app Y)) b₀ = (ConcreteCategory.hom (A.obj.map f)) m
Z : C
g : Z ⟶ Opposite.unop Y
hg : S.arrows (g ≫ f.unop)
⊢ (ConcreteCategory.hom (α.app (Opposite.op Z))) (r₀ (g ≫ f.unop) hg) =
    (ConcreteCategory.hom (α.app (Opposite.op Z))) ((ConcreteCategory.hom (R₀.map g.op)) a₀)

pp: case refine_2
C : Type u₁
inst✝⁴ : Category.{v₁, u₁} C
J : GrothendieckTopology C
R₀ : Cᵒᵖ ⥤ RingCat
R : Sheaf J RingCat
α : R₀ ⟶ R.obj
inst✝³ : Presheaf.IsLocallyInjective J α
inst✝² : Presheaf.IsLocallySurjective J α
M₀ : PresheafOfModules R₀
A : Sheaf J AddCommGrpCat
φ : M₀.presheaf ⟶ A.obj
inst✝¹ : Presheaf.IsLocallyInjective J φ
inst✝ : Presheaf.IsLocallySurjective J φ
X Y✝ : Cᵒᵖ
π : X ⟶ Y✝
r r' : ↑(R.obj.obj X)
m m' : ↑(A.obj.obj X)
S : Sieve (Opposite.unop X)
hS : S ∈ J (Opposite.unop X)
r₀ : Presieve.FamilyOfElements (R₀ ⋙ forget RingCat) S.arrows
m₀ : Presieve.FamilyOfElements (M₀.presheaf ⋙ forget Ab) S.arrows
hr₀ : (r₀.map (whiskerRight α (forget RingCat))).IsAmalgamation r
hm₀ : (m₀.map (whiskerRight φ (forget Ab))).IsAmalgamation m
a : ↑(A.obj.obj X)
ha : ((r₀.smul m₀).map (whiskerRight φ (forget Ab))).IsAmalgamation a
Y : Cᵒᵖ
f : X ⟶ Y
a₀ : ↑(R₀.obj Y)
ha₀ : (ConcreteCategory.hom (α.app Y)) a₀ = (ConcreteCategory.hom (R.obj.map f)) r
b₀ : ↑(M₀.obj Y)
hb₀ : (ConcreteCategory.hom (φ.app Y)) b₀ = (ConcreteCategory.hom (A.obj.map f)) m
Z : C
g : Z ⟶ Opposite.unop Y
hg : S.arrows (g ≫ f.unop)
⊢ (ConcreteCategory.hom (φ.app (Opposite.op Z))) (m₀ (g ≫ f.unop) hg) =
    (ConcreteCategory.hom (φ.app (Opposite.op Z))) ((ConcreteCategory.hom (M₀.map g.op)) b₀)

Tactic:
· rw [← RingCat.comp_apply, NatTrans.naturality, RingCat.comp_apply, ha₀]
      apply (hr₀ _ hg).symm.trans
      simp

Goal state after:
case refine_2
C : Type u₁
inst✝⁴ : Category.{v₁, u₁} C
J : GrothendieckTopology C
R₀ : Cᵒᵖ ⥤ RingCat
R : Sheaf J RingCat
α : R₀ ⟶ R.obj
inst✝³ : Presheaf.IsLocallyInjective J α
inst✝² : Presheaf.IsLocallySurjective J α
M₀ : PresheafOfModules R₀
A : Sheaf J AddCommGrpCat
φ : M₀.presheaf ⟶ A.obj
inst✝¹ : Presheaf.IsLocallyInjective J φ
inst✝ : Presheaf.IsLocallySurjective J φ
X Y✝ : Cᵒᵖ
π : X ⟶ Y✝
r r' : ↑(R.obj.obj X)
m m' : ↑(A.obj.obj X)
S : Sieve (Opposite.unop X)
hS : S ∈ J (Opposite.unop X)
r₀ : Presieve.FamilyOfElements (R₀ ⋙ forget RingCat) S.arrows
m₀ : Presieve.FamilyOfElements (M₀.presheaf ⋙ forget Ab) S.arrows
hr₀ : (r₀.map (whiskerRight α (forget RingCat))).IsAmalgamation r
hm₀ : (m₀.map (whiskerRight φ (forget Ab))).IsAmalgamation m
a : ↑(A.obj.obj X)
ha : ((r₀.smul m₀).map (whiskerRight φ (forget Ab))).IsAmalgamation a
Y : Cᵒᵖ
f : X ⟶ Y
a₀ : ↑(R₀.obj Y)
ha₀ : (ConcreteCategory.hom (α.app Y)) a₀ = (ConcreteCategory.hom (R.obj.map f)) r
b₀ : ↑(M₀.obj Y)
hb₀ : (ConcreteCategory.hom (φ.app Y)) b₀ = (ConcreteCategory.hom (A.obj.map f)) m
Z : C
g : Z ⟶ Opposite.unop Y
hg : S.arrows (g ≫ f.unop)
⊢ (ConcreteCategory.hom (φ.app (Opposite.op Z))) (m₀ (g ≫ f.unop) hg) =
    (ConcreteCategory.hom (φ.app (Opposite.op Z))) ((ConcreteCategory.hom (M₀.map g.op)) b₀)