Module: Mathlib.AlgebraicGeometry.Sites.ConstantSheaf

Goal state before:
pp: case refine_2.refine_1
T : Type v
inst✝ : TopologicalSpace T
R S : CommRingCat
f : R ⟶ S
hf₁ : Flat (Spec.map f)
hf₂ : Surjective (Spec.map f)
this : Topology.IsQuotientMap ⇑(Spec.map f)
x : C(↥(Spec S), T)
h :
  ∀ {Z : Scheme} (p₁ p₂ : Z ⟶ Spec S),
    p₁ ≫ Spec.map f = p₂ ≫ Spec.map f →
      (ConcreteCategory.hom ((continuousMapPresheaf T).map p₁.op)) x =
        (ConcreteCategory.hom ((continuousMapPresheaf T).map p₂.op)) x
⊢ (fun X ↦ X) ((continuousMapPresheaf T).obj (Opposite.op (Spec R)))

pp: case refine_2.refine_2
T : Type v
inst✝ : TopologicalSpace T
R S : CommRingCat
f : R ⟶ S
hf₁ : Flat (Spec.map f)
hf₂ : Surjective (Spec.map f)
this : Topology.IsQuotientMap ⇑(Spec.map f)
x : C(↥(Spec S), T)
h :
  ∀ {Z : Scheme} (p₁ p₂ : Z ⟶ Spec S),
    p₁ ≫ Spec.map f = p₂ ≫ Spec.map f →
      (ConcreteCategory.hom ((continuousMapPresheaf T).map p₁.op)) x =
        (ConcreteCategory.hom ((continuousMapPresheaf T).map p₂.op)) x
⊢ (fun y ↦ (ConcreteCategory.hom ((continuousMapPresheaf T).map (Spec.map f).op)) y = x) ?refine_2.refine_1

pp: case refine_2.refine_3
T : Type v
inst✝ : TopologicalSpace T
R S : CommRingCat
f : R ⟶ S
hf₁ : Flat (Spec.map f)
hf₂ : Surjective (Spec.map f)
this : Topology.IsQuotientMap ⇑(Spec.map f)
x : C(↥(Spec S), T)
h :
  ∀ {Z : Scheme} (p₁ p₂ : Z ⟶ Spec S),
    p₁ ≫ Spec.map f = p₂ ≫ Spec.map f →
      (ConcreteCategory.hom ((continuousMapPresheaf T).map p₁.op)) x =
        (ConcreteCategory.hom ((continuousMapPresheaf T).map p₂.op)) x
⊢ ∀ (y : (fun X ↦ X) ((continuousMapPresheaf T).obj (Opposite.op (Spec R)))),
    (fun y ↦ (ConcreteCategory.hom ((continuousMapPresheaf T).map (Spec.map f).op)) y = x) y → y = ?refine_2.refine_1

Tactic:
· refine Topology.IsQuotientMap.lift this x fun a b hfab ↦ ?_
      obtain ⟨c, rfl, rfl⟩ := Scheme.Pullback.exists_preimage_pullback a b hfab
      exact congr($(h (pullback.fst (Spec.map f) (Spec.map f))
        (pullback.snd _ _) pullback.condition).1 c)

Goal state after:
case refine_2.refine_2
T : Type v
inst✝ : TopologicalSpace T
R S : CommRingCat
f : R ⟶ S
hf₁ : Flat (Spec.map f)
hf₂ : Surjective (Spec.map f)
this : Topology.IsQuotientMap ⇑(Spec.map f)
x : C(↥(Spec S), T)
h :
  ∀ {Z : Scheme} (p₁ p₂ : Z ⟶ Spec S),
    p₁ ≫ Spec.map f = p₂ ≫ Spec.map f →
      (ConcreteCategory.hom ((continuousMapPresheaf T).map p₁.op)) x =
        (ConcreteCategory.hom ((continuousMapPresheaf T).map p₂.op)) x
⊢ (fun y ↦ (ConcreteCategory.hom ((continuousMapPresheaf T).map (Spec.map f).op)) y = x) (this.lift x ⋯)

case refine_2.refine_3
T : Type v
inst✝ : TopologicalSpace T
R S : CommRingCat
f : R ⟶ S
hf₁ : Flat (Spec.map f)
hf₂ : Surjective (Spec.map f)
this : Topology.IsQuotientMap ⇑(Spec.map f)
x : C(↥(Spec S), T)
h :
  ∀ {Z : Scheme} (p₁ p₂ : Z ⟶ Spec S),
    p₁ ≫ Spec.map f = p₂ ≫ Spec.map f →
      (ConcreteCategory.hom ((continuousMapPresheaf T).map p₁.op)) x =
        (ConcreteCategory.hom ((continuousMapPresheaf T).map p₂.op)) x
⊢ ∀ (y : (fun X ↦ X) ((continuousMapPresheaf T).obj (Opposite.op (Spec R)))),
    (fun y ↦ (ConcreteCategory.hom ((continuousMapPresheaf T).map (Spec.map f).op)) y = x) y → y = this.lift x ⋯