-- Mathlib/AlgebraicGeometry/ValuativeCriterion.lean
@[stacks 01KZ]
lemma IsSeparated.valuativeCriterion [IsSeparated f] : ValuativeCriterion.Uniqueness f

Proof state:
case allEq.mk.mk.l
X Y : Scheme
f : X ⟶ Y
inst✝ : IsSeparated f
S : ValuativeCommSq f
l₁ : Spec (CommRingCat.of S.R) ⟶ X
hl₁ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₁ = S.i₁
hl₁' : l₁ ≫ f = S.i₂
l₂ : Spec (CommRingCat.of S.R) ⟶ X
hl₂ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₂ = S.i₁
hl₂' : l₂ ≫ f = S.i₂
h : l₁ ≫ f = l₂ ≫ f
Z : Scheme := pullback (pullback.diagonal f) (pullback.lift l₁ l₂ h)
g : Z ⟶ Spec (CommRingCat.of S.R) := pullback.snd (pullback.diagonal f) (pullback.lift l₁ l₂ h)
this : IsClosedImmersion g
hZ : IsAffine Z
⊢ Function.Bijective ⇑(ConcreteCategory.hom (Scheme.Hom.appTop g))

Tactic:
constructor

Result:
case allEq.mk.mk.l.left
X Y : Scheme
f : X ⟶ Y
inst✝ : IsSeparated f
S : ValuativeCommSq f
l₁ : Spec (CommRingCat.of S.R) ⟶ X
hl₁ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₁ = S.i₁
hl₁' : l₁ ≫ f = S.i₂
l₂ : Spec (CommRingCat.of S.R) ⟶ X
hl₂ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₂ = S.i₁
hl₂' : l₂ ≫ f = S.i₂
h : l₁ ≫ f = l₂ ≫ f
Z : Scheme := pullback (pullback.diagonal f) (pullback.lift l₁ l₂ h)
g : Z ⟶ Spec (CommRingCat.of S.R) := pullback.snd (pullback.diagonal f) (pullback.lift l₁ l₂ h)
this : IsClosedImmersion g
hZ : IsAffine Z
⊢ Function.Injective ⇑(ConcreteCategory.hom (Scheme.Hom.appTop g))

case allEq.mk.mk.l.right
X Y : Scheme
f : X ⟶ Y
inst✝ : IsSeparated f
S : ValuativeCommSq f
l₁ : Spec (CommRingCat.of S.R) ⟶ X
hl₁ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₁ = S.i₁
hl₁' : l₁ ≫ f = S.i₂
l₂ : Spec (CommRingCat.of S.R) ⟶ X
hl₂ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₂ = S.i₁
hl₂' : l₂ ≫ f = S.i₂
h : l₁ ≫ f = l₂ ≫ f
Z : Scheme := pullback (pullback.diagonal f) (pullback.lift l₁ l₂ h)
g : Z ⟶ Spec (CommRingCat.of S.R) := pullback.snd (pullback.diagonal f) (pullback.lift l₁ l₂ h)
this : IsClosedImmersion g
hZ : IsAffine Z
⊢ Function.Surjective ⇑(ConcreteCategory.hom (Scheme.Hom.appTop g))

Proof state:
X Y : Scheme
f : X ⟶ Y
inst✝ : IsSeparated f
⊢ ValuativeCriterion.Uniqueness f

Tactic:
intros S

Result:
X Y : Scheme
f : X ⟶ Y
inst✝ : IsSeparated f
S : ValuativeCommSq f
⊢ Subsingleton ⋯.LiftStruct

Proof state:
case allEq.mk.mk.l.right
X Y : Scheme
f : X ⟶ Y
inst✝ : IsSeparated f
S : ValuativeCommSq f
l₁ : Spec (CommRingCat.of S.R) ⟶ X
hl₁ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₁ = S.i₁
hl₁' : l₁ ≫ f = S.i₂
l₂ : Spec (CommRingCat.of S.R) ⟶ X
hl₂ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₂ = S.i₁
hl₂' : l₂ ≫ f = S.i₂
h : l₁ ≫ f = l₂ ≫ f
Z : Scheme := pullback (pullback.diagonal f) (pullback.lift l₁ l₂ h)
g : Z ⟶ Spec (CommRingCat.of S.R) := pullback.snd (pullback.diagonal f) (pullback.lift l₁ l₂ h)
this : IsAffine Z ∧ Function.Surjective ⇑(ConcreteCategory.hom (Scheme.Hom.appTop g))
hZ : IsAffine Z
⊢ Function.Surjective ⇑(ConcreteCategory.hom (Scheme.Hom.appTop g))

Tactic:
exact this.right

Result:
no goals

Proof state:
X Y : Scheme
f : X ⟶ Y
inst✝ : IsSeparated f
S : ValuativeCommSq f
l₁ : Spec (CommRingCat.of S.R) ⟶ X
hl₁ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₁ = S.i₁
hl₁' : l₁ ≫ f = S.i₂
l₂ : Spec (CommRingCat.of S.R) ⟶ X
hl₂ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₂ = S.i₁
hl₂' : l₂ ≫ f = S.i₂
h : l₁ ≫ f = l₂ ≫ f
Z : Scheme := pullback (pullback.diagonal f) (pullback.lift l₁ l₂ h)
g : Z ⟶ Spec (CommRingCat.of S.R) := pullback.snd (pullback.diagonal f) (pullback.lift l₁ l₂ h)
this✝ : IsClosedImmersion g
hZ : IsAffine Z
l : Spec (CommRingCat.of S.K) ⟶ Z := pullback.lift S.i₁ (Spec.map (CommRingCat.ofHom (algebraMap S.R S.K))) ⋯
hg : l ≫ g = Spec.map (CommRingCat.ofHom (algebraMap S.R S.K))
e : Arrow.mk (CommRingCat.ofHom (algebraMap S.R S.K)) ≅
  Arrow.mk (Scheme.Hom.appTop (Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)))) :=
  arrowIsoΓSpecOfIsAffine (CommRingCat.ofHom (algebraMap S.R S.K))
P : MorphismProperty CommRingCat :=
  RingHom.toMorphismProperty fun {R S} [CommRing R] [CommRing S] f => Function.Injective ⇑f
this : (RingHom.toMorphismProperty fun {R S} [CommRing R] [CommRing S] f => Function.Injective ⇑f).RespectsIso
⊢ Function.Injective ⇑(ConcreteCategory.hom (Scheme.Hom.appTop (Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)))))

Tactic:
show P _

Result:
X Y : Scheme
f : X ⟶ Y
inst✝ : IsSeparated f
S : ValuativeCommSq f
l₁ : Spec (CommRingCat.of S.R) ⟶ X
hl₁ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₁ = S.i₁
hl₁' : l₁ ≫ f = S.i₂
l₂ : Spec (CommRingCat.of S.R) ⟶ X
hl₂ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₂ = S.i₁
hl₂' : l₂ ≫ f = S.i₂
h : l₁ ≫ f = l₂ ≫ f
Z : Scheme := pullback (pullback.diagonal f) (pullback.lift l₁ l₂ h)
g : Z ⟶ Spec (CommRingCat.of S.R) := pullback.snd (pullback.diagonal f) (pullback.lift l₁ l₂ h)
this✝ : IsClosedImmersion g
hZ : IsAffine Z
l : Spec (CommRingCat.of S.K) ⟶ Z := pullback.lift S.i₁ (Spec.map (CommRingCat.ofHom (algebraMap S.R S.K))) ⋯
hg : l ≫ g = Spec.map (CommRingCat.ofHom (algebraMap S.R S.K))
e : Arrow.mk (CommRingCat.ofHom (algebraMap S.R S.K)) ≅
  Arrow.mk (Scheme.Hom.appTop (Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)))) :=
  arrowIsoΓSpecOfIsAffine (CommRingCat.ofHom (algebraMap S.R S.K))
P : MorphismProperty CommRingCat :=
  RingHom.toMorphismProperty fun {R S} [CommRing R] [CommRing S] f => Function.Injective ⇑f
this : (RingHom.toMorphismProperty fun {R S} [CommRing R] [CommRing S] f => Function.Injective ⇑f).RespectsIso
⊢ P (Scheme.Hom.appTop (Spec.map (CommRingCat.ofHom (algebraMap S.R S.K))))

Proof state:
case allEq.mk.mk.l
X Y : Scheme
f : X ⟶ Y
inst✝ : IsSeparated f
S : ValuativeCommSq f
l₁ : Spec (CommRingCat.of S.R) ⟶ X
hl₁ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₁ = S.i₁
hl₁' : l₁ ≫ f = S.i₂
l₂ : Spec (CommRingCat.of S.R) ⟶ X
hl₂ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₂ = S.i₁
hl₂' : l₂ ≫ f = S.i₂
⊢ l₁ = l₂

Tactic:
have h := hl₁'.trans hl₂'.symm

Result:
case allEq.mk.mk.l
X Y : Scheme
f : X ⟶ Y
inst✝ : IsSeparated f
S : ValuativeCommSq f
l₁ : Spec (CommRingCat.of S.R) ⟶ X
hl₁ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₁ = S.i₁
hl₁' : l₁ ≫ f = S.i₂
l₂ : Spec (CommRingCat.of S.R) ⟶ X
hl₂ : Spec.map (CommRingCat.ofHom (algebraMap S.R S.K)) ≫ l₂ = S.i₁
hl₂' : l₂ ≫ f = S.i₂
h : l₁ ≫ f = l₂ ≫ f
⊢ l₁ = l₂