mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.RingTheory.Finiteness.FinitePresentationLocal

Goal state before:
pp: R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
s✝ : Set S
hs✝ : Ideal.span s✝ = ⊤
s : Finset S
h₁ : ↑s ⊆ s✝
hs : Ideal.span ↑s = ⊤
h : ∀ (i : ↥s), FinitePresentation R (Localization.Away ↑i)
hfintype : FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
l : ↑↑s →₀ S
hl : (Finsupp.linearCombination S Subtype.val) l = 1
g' : ↥s → MvPolynomial (Fin n) R
hg' : ∀ (g : ↥s), f (g' g) = ↑g
h' : ↥s → MvPolynomial (Fin n) R
hh' : ∀ (g : ↥s), f (h' g) = l g
I : Ideal (MvPolynomial (Fin n) R) := Ideal.span {∑ g, g' g * h' g - 1}
A : Type u_1 := MvPolynomial (Fin n) R ⧸ I
q : MvPolynomial (Fin n) R
⊢ (∑ x ∈ s.attach, ↑x * l x - 1) * f q = 0

Tactic:
rw [Finsupp.linearCombination_apply_of_mem_supported (α := (s : Set S)) S (s := s.attach)] at hl

Goal state after:
R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
s✝ : Set S
hs✝ : Ideal.span s✝ = ⊤
s : Finset S
h₁ : ↑s ⊆ s✝
hs : Ideal.span ↑s = ⊤
h : ∀ (i : ↥s), FinitePresentation R (Localization.Away ↑i)
hfintype : FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
l : ↑↑s →₀ S
hl : ∑ i ∈ s.attach, l i • ↑i = 1
g' : ↥s → MvPolynomial (Fin n) R
hg' : ∀ (g : ↥s), f (g' g) = ↑g
h' : ↥s → MvPolynomial (Fin n) R
hh' : ∀ (g : ↥s), f (h' g) = l g
I : Ideal (MvPolynomial (Fin n) R) := Ideal.span {∑ g, g' g * h' g - 1}
A : Type u_1 := MvPolynomial (Fin n) R ⧸ I
q : MvPolynomial (Fin n) R
⊢ (∑ x ∈ s.attach, ↑x * l x - 1) * f q = 0

R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
s✝ : Set S
hs✝ : Ideal.span s✝ = ⊤
s : Finset S
h₁ : ↑s ⊆ s✝
hs : Ideal.span ↑s = ⊤
h : ∀ (i : ↥s), FinitePresentation R (Localization.Away ↑i)
hfintype : FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
l : ↑↑s →₀ S
hl : (Finsupp.linearCombination S Subtype.val) l = 1
g' : ↥s → MvPolynomial (Fin n) R
hg' : ∀ (g : ↥s), f (g' g) = ↑g
h' : ↥s → MvPolynomial (Fin n) R
hh' : ∀ (g : ↥s), f (h' g) = l g
I : Ideal (MvPolynomial (Fin n) R) := Ideal.span {∑ g, g' g * h' g - 1}
A : Type u_1 := MvPolynomial (Fin n) R ⧸ I
q : MvPolynomial (Fin n) R
⊢ l ∈ Finsupp.supported S S ↑s.attach
Module: Mathlib.RingTheory.Finiteness.FinitePresentationLocal

Goal state before:
pp: R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
s✝ : Set S
hs✝ : Ideal.span s✝ = ⊤
s : Finset S
h₁ : ↑s ⊆ s✝
hs : Ideal.span ↑s = ⊤
h : ∀ (i : ↥s), FinitePresentation R (Localization.Away ↑i)
hfintype : FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
l : ↑↑s →₀ S
hl : (Finsupp.linearCombination S Subtype.val) l = 1
g' : ↥s → MvPolynomial (Fin n) R
hg' : ∀ (g : ↥s), f (g' g) = ↑g
h' : ↥s → MvPolynomial (Fin n) R
hh' : ∀ (g : ↥s), f (h' g) = l g
I : Ideal (MvPolynomial (Fin n) R) := Ideal.span {∑ g, g' g * h' g - 1}
A : Type u_1 := MvPolynomial (Fin n) R ⧸ I
hfI : ∀ a ∈ I, f a = 0
f' : A →ₐ[R] S := Ideal.Quotient.liftₐ I f hfI
hf' : Function.Surjective ⇑f'
t : Finset A := Finset.image (fun g ↦ (Ideal.Quotient.mk I) (g' g)) Finset.univ
ht : Ideal.span ↑t = ⊤
this : FinitePresentation R A
g : ↥t
r : S
hr : r ∈ s
hrr : (Ideal.Quotient.mk I) (g' ⟨r, hr⟩) = ↑g
⊢ FinitePresentation R (Localization.Away (f' ↑g))

Tactic:
simp only [f']

Goal state after:
R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
s✝ : Set S
hs✝ : Ideal.span s✝ = ⊤
s : Finset S
h₁ : ↑s ⊆ s✝
hs : Ideal.span ↑s = ⊤
h : ∀ (i : ↥s), FinitePresentation R (Localization.Away ↑i)
hfintype : FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
l : ↑↑s →₀ S
hl : (Finsupp.linearCombination S Subtype.val) l = 1
g' : ↥s → MvPolynomial (Fin n) R
hg' : ∀ (g : ↥s), f (g' g) = ↑g
h' : ↥s → MvPolynomial (Fin n) R
hh' : ∀ (g : ↥s), f (h' g) = l g
I : Ideal (MvPolynomial (Fin n) R) := Ideal.span {∑ g, g' g * h' g - 1}
A : Type u_1 := MvPolynomial (Fin n) R ⧸ I
hfI : ∀ a ∈ I, f a = 0
f' : A →ₐ[R] S := Ideal.Quotient.liftₐ I f hfI
hf' : Function.Surjective ⇑f'
t : Finset A := Finset.image (fun g ↦ (Ideal.Quotient.mk I) (g' g)) Finset.univ
ht : Ideal.span ↑t = ⊤
this : FinitePresentation R A
g : ↥t
r : S
hr : r ∈ s
hrr : (Ideal.Quotient.mk I) (g' ⟨r, hr⟩) = ↑g
⊢ FinitePresentation R (Localization.Away ((Ideal.Quotient.liftₐ I f hfI) ↑g))
Module: Mathlib.RingTheory.Spectrum.Prime.Chevalley

Goal state before:
pp: case refine_2
R : Type u_1
S : Type u_2
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
hf : f.FinitePresentation
s : Set (PrimeSpectrum S)
hs : IsConstructible s
⊢ ∀ (R : Type u_1) [inst : CommRing R] (S : Type u_1) [inst_1 : CommRing S] (T : Type u_2) [inst_2 : CommRing T]
    (f : R →+* S) (g : S →+* T),
    (∀ (s : Set (PrimeSpectrum S)), IsConstructible s → IsConstructible (comap f '' s)) →
      (∀ (s : Set (PrimeSpectrum T)), IsConstructible s → IsConstructible (comap g '' s)) →
        ∀ (s : Set (PrimeSpectrum T)), IsConstructible s → IsConstructible (comap (g.comp f) '' s)

Tactic:
· intro R _ S _ T _ f g H₁ H₂ s hs
    simp only [comap_comp, Set.image_comp]
    exact H₁ _ (H₂ _ hs)

Goal state after:
Module: Mathlib.RingTheory.Spectrum.Prime.Chevalley

Goal state before:
pp: K : Type u_3
A : Type u_4
B : Type u_5
inst✝⁴ : Field K
inst✝³ : CommRing A
inst✝² : CommRing B
inst✝¹ : Algebra K A
inst✝ : Algebra K B
B' : Subalgebra K B
hB : B'.FG
f : A ⊗[K] ↥B'
hU : IsOpen ↑(basicOpen ((Algebra.TensorProduct.map (AlgHom.id A A) B'.val).toRingHom f))
this : Algebra.FinitePresentation K ↥B'
x : PrimeSpectrum A
ψ : A ⊗[K] ↥B' ⊗[A] x.asIdeal.ResidueField →ₐ[A] A ⊗[K] B ⊗[A] x.asIdeal.ResidueField :=
  Algebra.TensorProduct.map (Algebra.TensorProduct.map (AlgHom.id A A) B'.val) (AlgHom.id A x.asIdeal.ResidueField)
⊢ IsNilpotent
      ((algebraMap (A ⊗[K] B) (A ⊗[K] B ⊗[A] x.asIdeal.ResidueField))
        ((Algebra.TensorProduct.map (AlgHom.id A A) B'.val).toRingHom f)) ↔
    IsNilpotent ((algebraMap (A ⊗[K] ↥B') (A ⊗[K] ↥B' ⊗[A] x.asIdeal.ResidueField)) f)

Tactic:
have hψeq : ψ = (Algebra.TensorProduct.comm _ _ _ |>.toAlgHom.comp <|
    Algebra.TensorProduct.cancelBaseChange K A A _ B |>.symm.toAlgHom.comp <|
    Algebra.TensorProduct.map (.id _ _) B'.val |>.comp <|
    Algebra.TensorProduct.cancelBaseChange K A A _ B' |>.toAlgHom.comp <|
    (Algebra.TensorProduct.comm _ _ _).toAlgHom) := by ext; simp [ψ]

Goal state after:
K : Type u_3
A : Type u_4
B : Type u_5
inst✝⁴ : Field K
inst✝³ : CommRing A
inst✝² : CommRing B
inst✝¹ : Algebra K A
inst✝ : Algebra K B
B' : Subalgebra K B
hB : B'.FG
f : A ⊗[K] ↥B'
hU : IsOpen ↑(basicOpen ((Algebra.TensorProduct.map (AlgHom.id A A) B'.val).toRingHom f))
this : Algebra.FinitePresentation K ↥B'
x : PrimeSpectrum A
ψ : A ⊗[K] ↥B' ⊗[A] x.asIdeal.ResidueField →ₐ[A] A ⊗[K] B ⊗[A] x.asIdeal.ResidueField :=
  Algebra.TensorProduct.map (Algebra.TensorProduct.map (AlgHom.id A A) B'.val) (AlgHom.id A x.asIdeal.ResidueField)
hψeq :
  ψ =
    (↑(Algebra.TensorProduct.comm A x.asIdeal.ResidueField (A ⊗[K] B))).comp
      ((↑(Algebra.TensorProduct.cancelBaseChange K A A x.asIdeal.ResidueField B).symm).comp
        ((Algebra.TensorProduct.map (AlgHom.id A x.asIdeal.ResidueField) B'.val).comp
          ((↑(Algebra.TensorProduct.cancelBaseChange K A A x.asIdeal.ResidueField ↥B')).comp
            ↑(Algebra.TensorProduct.comm A (A ⊗[K] ↥B') x.asIdeal.ResidueField))))
⊢ IsNilpotent
      ((algebraMap (A ⊗[K] B) (A ⊗[K] B ⊗[A] x.asIdeal.ResidueField))
        ((Algebra.TensorProduct.map (AlgHom.id A A) B'.val).toRingHom f)) ↔
    IsNilpotent ((algebraMap (A ⊗[K] ↥B') (A ⊗[K] ↥B' ⊗[A] x.asIdeal.ResidueField)) f)
Module: Mathlib.AlgebraicGeometry.Geometrically.Basic

Goal state before:
pp: P : ObjectProperty Scheme
inst✝ : P.IsClosedUnderIsomorphisms
⊢ IsZariskiLocalAtTarget (geometrically P)

Tactic:
by
  rw [geometrically_eq_universally]
  refine universally_isZariskiLocalAtTarget _ fun {X} Y f ι U hU H _ _ ↦ ?_
  obtain ⟨y⟩ := (inferInstance : Nonempty Y)
  obtain ⟨i, hy⟩ := hU.exists_mem y
  have heq : U i = ⊤ := eq_top_iff.mpr fun z _ ↦ by rwa [Subsingleton.elim z y]
  let e : ↑(U i) ≅ Y := Y.isoOfEq heq ≪≫ Y.topIso
  let e' : ↑(f ⁻¹ᵁ U i) ≅ X := X.isoOfEq (by simp [heq]) ≪≫ X.topIso
  exact P.prop_of_iso e' <| H i (.of_isIso e.inv) (e.hom.homeomorph.subsingleton_congr.mpr ‹_›)

Goal state after:
Module: Mathlib.AlgebraicGeometry.Geometrically.Basic

Goal state before:
pp: P : ObjectProperty Scheme
X Y : Scheme
f : X ⟶ Y
inst✝¹ : IsIntegral Y
inst✝ : Subsingleton ↥Y
hf : geometrically P f
⊢ P X

Tactic:
rw [geometrically_eq_universally] at hf
  exact MorphismProperty.universally_le _ _ hf ‹_› ‹_›

Goal state after:
Module: Mathlib.AlgebraicGeometry.Geometrically.Irreducible

Goal state before:
pp: X Y : Scheme
Z : Scheme
S : Scheme
f✝ : X ⟶ S
g✝ : Y ⟶ S
U : Scheme
f : U ⟶ X
g : X ⟶ S
inst✝² : IsOpenImmersion f
inst✝¹ : GeometricallyIrreducible g
inst✝ : Surjective (f ≫ g)
s : ↥S
K : Type u
x✝ : Field K
x : Spec (CommRingCat.of K) ⟶ Spec (S.residueField s)
i : pullback (Scheme.Hom.fiberToSpecResidueField (f ≫ g) s) x ⟶ pullback (Scheme.Hom.fiberToSpecResidueField g s) x :=
  pullback.map (Scheme.Hom.fiberToSpecResidueField (f ≫ g) s) x (Scheme.Hom.fiberToSpecResidueField g s) x
    (pullback.map (f ≫ g) (S.fromSpecResidueField s) g (S.fromSpecResidueField s) f (𝟙 (Spec (S.residueField s))) (𝟙 S)
      ⋯ ⋯)
    (𝟙 (Spec (CommRingCat.of K))) (𝟙 (Spec (S.residueField s))) ⋯ ⋯
⊢ IrreducibleSpace ↥(pullback (Scheme.Hom.fiberToSpecResidueField (f ≫ g) s) x)

Tactic:
have : Nonempty ((f ≫ g).fiber s) := by
    rw [((f ≫ g).fiberHomeo s).nonempty_congr, Set.nonempty_coe_sort]
    exact (Set.singleton_nonempty s).preimage (f ≫ g).surjective

Goal state after:
X Y : Scheme
Z : Scheme
S : Scheme
f✝ : X ⟶ S
g✝ : Y ⟶ S
U : Scheme
f : U ⟶ X
g : X ⟶ S
inst✝² : IsOpenImmersion f
inst✝¹ : GeometricallyIrreducible g
inst✝ : Surjective (f ≫ g)
s : ↥S
K : Type u
x✝ : Field K
x : Spec (CommRingCat.of K) ⟶ Spec (S.residueField s)
i : pullback (Scheme.Hom.fiberToSpecResidueField (f ≫ g) s) x ⟶ pullback (Scheme.Hom.fiberToSpecResidueField g s) x :=
  pullback.map (Scheme.Hom.fiberToSpecResidueField (f ≫ g) s) x (Scheme.Hom.fiberToSpecResidueField g s) x
    (pullback.map (f ≫ g) (S.fromSpecResidueField s) g (S.fromSpecResidueField s) f (𝟙 (Spec (S.residueField s))) (𝟙 S)
      ⋯ ⋯)
    (𝟙 (Spec (CommRingCat.of K))) (𝟙 (Spec (S.residueField s))) ⋯ ⋯
this : Nonempty ↥(Scheme.Hom.fiber (f ≫ g) s)
⊢ IrreducibleSpace ↥(pullback (Scheme.Hom.fiberToSpecResidueField (f ≫ g) s) x)
Module: Mathlib.AlgebraicGeometry.Morphisms.UniversallyOpen

Goal state before:
pp: X Y : Scheme
f : X ⟶ Y
inst✝ : Flat f
this :
  HasRingHomProperty (topologically fun {α β} [TopologicalSpace α] [TopologicalSpace β] ↦ GeneralizingMap)
    fun {R S} [CommRing R] [CommRing S] f ↦
    topologically (fun {α β} [TopologicalSpace α] [TopologicalSpace β] ↦ GeneralizingMap)
      (Spec.map (CommRingCat.ofHom f))
⊢ GeneralizingMap ⇑f

Tactic:
change topologically GeneralizingMap f

Goal state after:
X Y : Scheme
f : X ⟶ Y
inst✝ : Flat f
this :
  HasRingHomProperty (topologically fun {α β} [TopologicalSpace α] [TopologicalSpace β] ↦ GeneralizingMap)
    fun {R S} [CommRing R] [CommRing S] f ↦
    topologically (fun {α β} [TopologicalSpace α] [TopologicalSpace β] ↦ GeneralizingMap)
      (Spec.map (CommRingCat.ofHom f))
⊢ topologically (fun {α β} [TopologicalSpace α] [TopologicalSpace β] ↦ GeneralizingMap) f
Module: Mathlib.AlgebraicGeometry.Morphisms.Finite

Goal state before:
pp: case inr
X Y : Scheme
f : X ⟶ Y
this : ∀ {X Y : Scheme} (f : X ⟶ Y), IsAffine Y → (IsFinite f ↔ IsIntegralHom f ∧ LocallyOfFiniteType f)
hY : ¬IsAffine Y
⊢ (∀ (i : Y.affineCover.toPreZeroHypercover.1), IsFinite (Scheme.Cover.pullbackHom Y.affineCover f i)) ↔
    (∀ (i : Y.affineCover.toPreZeroHypercover.1), IsIntegralHom (Scheme.Cover.pullbackHom Y.affineCover f i)) ∧
      LocallyOfFiniteType f

Tactic:
IsZariskiLocalAtTarget.iff_of_openCover (P := @LocallyOfFiniteType) Y.affineCover

Goal state after:
case inr
X Y : Scheme
f : X ⟶ Y
this : ∀ {X Y : Scheme} (f : X ⟶ Y), IsAffine Y → (IsFinite f ↔ IsIntegralHom f ∧ LocallyOfFiniteType f)
hY : ¬IsAffine Y
⊢ (∀ (i : Y.affineCover.toPreZeroHypercover.1), IsFinite (Scheme.Cover.pullbackHom Y.affineCover f i)) ↔
    (∀ (i : Y.affineCover.toPreZeroHypercover.1), IsIntegralHom (Scheme.Cover.pullbackHom Y.affineCover f i)) ∧
      ∀ (i : Y.affineCover.toPreZeroHypercover.1), LocallyOfFiniteType (Scheme.Cover.pullbackHom Y.affineCover f i)
Module: Mathlib.AlgebraicGeometry.Morphisms.Finite

Goal state before:
pp: case inr
X Y : Scheme
f : X ⟶ Y
inst✝² : Subsingleton ↥X
inst✝¹ : IsReduced X
inst✝ : JacobsonSpace ↥Y
this :
  ∀ {X Y : Scheme} {f : X ⟶ Y} [Subsingleton ↥X] [IsReduced X] [JacobsonSpace ↥Y],
    (∃ S, Y = Spec S) → (IsFinite f ↔ LocallyOfFiniteType f)
hY : ¬∃ S, Y = Spec S
⊢ (∀ (i : Y.affineCover.toPreZeroHypercover.1), IsFinite (Scheme.Cover.pullbackHom Y.affineCover f i)) ↔
    LocallyOfFiniteType f

Tactic:
IsZariskiLocalAtTarget.iff_of_openCover (P := @LocallyOfFiniteType) Y.affineCover

Goal state after:
case inr
X Y : Scheme
f : X ⟶ Y
inst✝² : Subsingleton ↥X
inst✝¹ : IsReduced X
inst✝ : JacobsonSpace ↥Y
this :
  ∀ {X Y : Scheme} {f : X ⟶ Y} [Subsingleton ↥X] [IsReduced X] [JacobsonSpace ↥Y],
    (∃ S, Y = Spec S) → (IsFinite f ↔ LocallyOfFiniteType f)
hY : ¬∃ S, Y = Spec S
⊢ (∀ (i : Y.affineCover.toPreZeroHypercover.1), IsFinite (Scheme.Cover.pullbackHom Y.affineCover f i)) ↔
    ∀ (i : Y.affineCover.toPreZeroHypercover.1), LocallyOfFiniteType (Scheme.Cover.pullbackHom Y.affineCover f i)
Module: Mathlib.AlgebraicGeometry.QuasiAffine

Goal state before:
pp: X : Scheme
inst✝ : CompactSpace ↥X
H : ∀ (x : ↥X), ∃ r, IsAffineOpen (X.basicOpen r) ∧ x ∈ X.basicOpen r
⊢ X.IsQuasiAffine

Tactic:
by
  suffices IsOpenImmersion X.toSpecΓ by constructor
  have : QuasiSeparatedSpace X := by
    choose r hr hxr using H
    exact .of_isOpenCover (U := (X.basicOpen <| r ·))
      (eq_top_iff.mpr fun _ _ ↦ Opens.mem_iSup.mpr ⟨_, hxr _⟩)
      (fun _ ↦ isRetrocompact_basicOpen _) (fun x ↦ (hr _).isQuasiSeparated)
  refine IsZariskiLocalAtTarget.of_forall_source_exists_preimage _ fun x ↦ ?_
  obtain ⟨r, hr, hxr⟩ := H x
  refine ⟨PrimeSpectrum.basicOpen r, (X.toSpecΓ_preimage_basicOpen r).ge hxr, ?_⟩
  suffices IsOpenImmersion ((X.basicOpen r).ι ≫ X.toSpecΓ) by
    convert! this <;> rw [toSpecΓ_preimage_basicOpen]
  rw [← Opens.toSpecΓ_SpecMap_presheaf_map_top]
  have := isLocalization_basicOpen_of_qcqs isCompact_univ isQuasiSeparated_univ r
  exact MorphismProperty.comp_mem _ hr.isoSpec.hom _ inferInstance (.of_isLocalization r)

Goal state after:
Module: Mathlib.AlgebraicGeometry.Morphisms.Flat

Goal state before:
pp: X Y : Scheme
f : X ⟶ Y
inst✝² : Flat f
inst✝¹ : QuasiCompact f
inst✝ : Surjective f
⊢ Topology.IsQuotientMap ⇑f

Tactic:
rw [Topology.isQuotientMap_iff]
  refine ⟨.of_isOpen_preimage_iff_isOpen fun s ↦
    ⟨fun hs ↦ ?_, fun hs ↦ hs.preimage f.continuous⟩, f.surjective⟩
  wlog hY : ∃ R, Y = Spec R
  · let 𝒰 := Y.affineCover
    rw [𝒰.isOpenCover_opensRange.isOpen_iff_inter]
    intro i
    rw [Scheme.Hom.coe_opensRange, ← Set.image_preimage_eq_inter_range]
    apply (𝒰.f i).isOpenEmbedding.isOpenMap
    refine this (f := pullback.fst (𝒰.f i) f) _ ?_ ⟨_, rfl⟩
    rw [← Set.preimage_comp, ← TopCat.coe_comp, ← Scheme.Hom.comp_base, pullback.condition,
      Scheme.Hom.comp_base, TopCat.coe_comp, Set.preimage_comp]
    exact hs.preimage (Scheme.Hom.continuous _)
  obtain ⟨R, rfl⟩ := hY
  wlog hX : ∃ S, X = Spec S
  · have _ : CompactSpace X := QuasiCompact.compactSpace_of_compactSpace f
    let 𝒰 := X.affineCover.finiteSubcover
    let p : ∐ (fun i : 𝒰.I₀ ↦ 𝒰.X i) ⟶ X := Sigma.desc (fun i ↦ 𝒰.f i)
    refine this (f := (∐ (fun i : 𝒰.I₀ ↦ 𝒰.X i)).isoSpec.inv ≫ p ≫ f) _ _ ?_ ⟨_, rfl⟩
    rw [← Category.assoc, Scheme.Hom.comp_base, TopCat.coe_comp, Set.preimage_comp]
    exact hs.preimage (_ ≫ p).continuous
  obtain ⟨S, rfl⟩ := hX
  obtain ⟨φ, rfl⟩ := Spec.map_surjective f
  refine ((PrimeSpectrum.isQuotientMap_of_generalizingMap ?_ ?_).isOpen_preimage).mp hs
  · exact (surjective_iff (Spec.map φ)).mp inferInstance
  · apply RingHom.Flat.generalizingMap_comap
    rwa [← HasRingHomProperty.Spec_iff (P := @Flat)]

Goal state after:
Module: Mathlib.Topology.LocallyFinsupp

Goal state before:
pp: X : Type u_1
inst✝³ : TopologicalSpace X
Y : Type u_2
inst✝² : DecidableEq X
inst✝¹ : Zero Y
inst✝ : Preorder Y
x : X
y : Y
⊢ 0 < single x y ↔ 0 < y

Tactic:
by
  rw [lt_def, coe_single]
  exact Pi.single_pos

Goal state after:
Module: Mathlib.Topology.LocallyFinsupp

Goal state before:
pp: X : Type u_1
inst✝² : TopologicalSpace X
U : Set X
Y : Type u_2
inst✝¹ : SemilatticeSup Y
inst✝ : Zero Y
D₁ D₂ : locallyFinsuppWithin U Y
x : X
hx : x ∉ U
⊢ x ∉ Function.support fun z ↦ D₁ z ⊔ D₂ z

Tactic:
simp [notMem_support.1 fun a ↦ hx (D₁.supportWithinDomain a),
        notMem_support.1 fun a ↦ hx (D₂.supportWithinDomain a)]

Goal state after:
Module: Mathlib.Topology.LocallyFinsupp

Goal state before:
pp: X : Type u_1
inst✝² : TopologicalSpace X
U : Set X
Y : Type u_2
inst✝¹ : SemilatticeInf Y
inst✝ : Zero Y
D₁ D₂ : locallyFinsuppWithin U Y
x : X
hx : x ∉ U
⊢ x ∉ Function.support fun z ↦ D₁ z ⊓ D₂ z

Tactic:
simp [notMem_support.1 fun a ↦ hx (D₁.supportWithinDomain a),
        notMem_support.1 fun a ↦ hx (D₂.supportWithinDomain a)]

Goal state after:
Module: Mathlib.Topology.LocallyFinsupp

Goal state before:
pp: X : Type u_1
inst✝² : TopologicalSpace X
Y : Type u_2
inst✝¹ : DecidableEq X
inst✝ : AddCommMonoid Y
U : Set X
F : locallyFinsuppWithin U Y
h : F.support.Finite
this : (Function.support fun x ↦ restrict (single x (F x)) ⋯) ⊆ ↑h.toFinset
⊢ ∑ᶠ (x : X), restrict (single x (F x)) ⋯ = F

Tactic:
finsum_eq_sum_of_support_subset _ this

Goal state after:
X : Type u_1
inst✝² : TopologicalSpace X
Y : Type u_2
inst✝¹ : DecidableEq X
inst✝ : AddCommMonoid Y
U : Set X
F : locallyFinsuppWithin U Y
h : F.support.Finite
this : (Function.support fun x ↦ restrict (single x (F x)) ⋯) ⊆ ↑h.toFinset
⊢ ∑ i ∈ h.toFinset, restrict (single i (F i)) ⋯ = F
Module: Mathlib.Topology.LocallyFinsupp.Pushforward

Goal state before:
pp: X : Type u_1
Y : Type u_2
R : Type u_3
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace Y
f : X → Y
hf✝ : IsSpectralMap f
w : X → R
inst✝¹ : Semiring R
W : Set Y
hW : IsOpen[inst✝²] W
c✝ : locallyFinsupp X R
inst✝ : PrespectralSpace Y
hf : IsSpectralMap f
c : locallyFinsupp X R
y : Y
x✝ : y ∈ univ
U : Set Y
hU : U ∈ {U | IsOpen[inst✝²] U ∧ IsCompact U} ∧ y ∈ U ∧ U ⊆ ⊤
this : (f ⁻¹' (U ∩ {z | (f ⁻¹' {z} ∩ locallyFinsuppWithin.support c).Nonempty}) ∩ locallyFinsuppWithin.support c).Finite
a : Y
ha : a ∈ U ∩ {z | (f ⁻¹' {z} ∩ support ⇑c).Nonempty}
⊢ a ∈ f '' (f ⁻¹' (U ∩ {z | (f ⁻¹' {z} ∩ locallyFinsuppWithin.support c).Nonempty}) ∩ locallyFinsuppWithin.support c)

Tactic:
by grind [Set.Nonempty]

Goal state after:
Module: Mathlib.AlgebraicGeometry.SpreadingOut

Goal state before:
pp: X Y : Scheme
f : X ⟶ Y
x : ↥X
inst✝ : IsOpenImmersion f
H✝ : Y.IsGermInjectiveAt (f x)
V : ↑X.affineOpens
hxU : f x ∈ f ''ᵁ ↑V
hU : IsAffineOpen (f ''ᵁ ↑V)
hU' : f ''ᵁ ↑V ≤ Scheme.Hom.opensRange f
H : Function.Injective ⇑(ConcreteCategory.hom (Y.presheaf.germ (f ''ᵁ ↑V) (f x) hxU))
hV : (IsOpenImmersion.affineOpensEquiv f) V = ⟨⟨f ''ᵁ ↑V, hU⟩, hU'⟩
⊢ X.IsGermInjectiveAt x

Tactic:
obtain ⟨y, hy, e : f y = f x⟩ := hxU

Goal state after:
X Y : Scheme
f : X ⟶ Y
x : ↥X
inst✝ : IsOpenImmersion f
H✝ : Y.IsGermInjectiveAt (f x)
V : ↑X.affineOpens
hU : IsAffineOpen (f ''ᵁ ↑V)
hU' : f ''ᵁ ↑V ≤ Scheme.Hom.opensRange f
hV : (IsOpenImmersion.affineOpensEquiv f) V = ⟨⟨f ''ᵁ ↑V, hU⟩, hU'⟩
y : ↥X
hy : y ∈ ↑↑V
e : f y = f x
H : Function.Injective ⇑(ConcreteCategory.hom (Y.presheaf.germ (f ''ᵁ ↑V) (f x) ⋯))
⊢ X.IsGermInjectiveAt x
Module: Mathlib.AlgebraicGeometry.Morphisms.Flat

Goal state before:
pp: X Y S T : Scheme
f : T ⟶ S
g : Y ⟶ X
iX : X ⟶ S
iY : Y ⟶ T
H : IsPullback g iY iX f
US : S.Opens
UT : T.Opens
UX : X.Opens
hUST : UT ≤ f ⁻¹ᵁ US
hUSX : UX ≤ iX ⁻¹ᵁ US
UY : Y.Opens
hUY : UY = g ⁻¹ᵁ UX ⊓ iY ⁻¹ᵁ UT
ι : Type u
inst✝ : Finite ι
VX : ι → X.Opens
hVU : iSup VX = UX
hV : ∀ (i : ι), IsIso (pushoutSection H hUST ⋯ ⋯)
hV' : ∀ (i j : ι), Mono (pushoutSection H hUST ⋯ ⋯)
hT : (CommRingCat.Hom.hom (Scheme.Hom.appLE f US UT hUST)).Flat
D : CategoryTheory.Pairwise ι ⥤ X.Opens := Pairwise.diagram VX
h : iSup D.obj = UX
c₀ : Cocone D := (colimit.cocone D).extend (eqToIso ⋯).hom
F : (CategoryTheory.Pairwise ι)ᵒᵖ ⥤ CommRingCat :=
  Under.lift (D.op ⋙ X.presheaf)
      ((Functor.const (CategoryTheory.Pairwise ι)ᵒᵖ).map (Scheme.Hom.appLE iX US UX hUSX) ≫
        (Functor.mapCone X.presheaf c₀.op).π) ⋙
    Under.pushout (Scheme.Hom.appLE f US UT hUST) ⋙ Under.forget Γ(T, UT)
G : X.Opens ⥤ Y.Opens :=
  { obj := fun U ↦ g ⁻¹ᵁ U ⊓ iY ⁻¹ᵁ UT, map := fun {X_1 Y_1} h ↦ homOfLE ⋯, map_id := ⋯, map_comp := ⋯ }
αF : F ⟶ D.op ⋙ G.op ⋙ Y.presheaf :=
  { app := fun i ↦ (pushout.congrHom ⋯ ⋯).hom ≫ pushoutSection H hUST ⋯ ⋯, naturality := ⋯ }
c : Cone F :=
  (Under.pushout (Scheme.Hom.appLE f US UT hUST) ⋙ Under.forget Γ(T, UT)).mapCone
    (Under.liftCone (Functor.mapCone X.presheaf c₀.op) (Scheme.Hom.appLE iX US UX hUSX))
this : PreservesFiniteLimits (Under.pushout (Scheme.Hom.appLE f US UT hUST))
val✝ : Fintype ι
hc : IsLimit c :=
  isLimitOfPreserves (Under.pushout (Scheme.Hom.appLE f US UT hUST) ⋙ Under.forget Γ(T, UT))
    (Under.isLimitLiftCone (Functor.mapCone X.presheaf c₀.op) (Scheme.Hom.appLE iX US UX hUSX) ⋯.some)
c'₀ : Cocone (D ⋙ G) := (colimit.cocone (D ⋙ G)).extend (eqToIso ⋯).hom
c' : Cone (D.op ⋙ G.op ⋙ Y.presheaf) := Functor.mapCone Y.presheaf c'₀.op
⊢ IsLimit c'

Tactic:
letI e : D ⋙ G ≅ Pairwise.diagram fun i ↦ g ⁻¹ᵁ VX i ⊓ iY ⁻¹ᵁ UT :=
      NatIso.ofComponents (fun | .single i => .refl _ | .pair i j => eqToIso (by
        dsimp [D, G]; rw [Scheme.Hom.preimage_inf, inf_inf_distrib_right]))
    haveI HX := ((TopCat.Presheaf.isSheaf_iff_isSheafPreservesLimitPairwiseIntersections _).mp
      Y.IsSheaf (fun i ↦ g ⁻¹ᵁ VX i ⊓ iY ⁻¹ᵁ UT)).preserves
        (c := ((Cocone.precompose e.inv).obj c'₀).op)
    exact (IsLimit.postcomposeHomEquiv (Functor.isoWhiskerRight (NatIso.op e.symm) Y.presheaf) _)
      ((HX ((IsColimit.precomposeInvEquiv e _).symm
        (IsColimit.extendIso _ (colimit.isColimit _))).op).some.ofIsoLimit (Cone.ext (.refl _)))

Goal state after:
Module: Mathlib.AlgebraicGeometry.SpreadingOut

Goal state before:
pp: case H
X Y : Scheme
x : ↥X
inst✝ : X.IsGermInjectiveAt x
f g : X ⟶ Y
e : X.fromSpecStalk x ≫ f = X.fromSpecStalk x ≫ g
⊢ Scheme.Hom.stalkMap f x = Y.presheaf.stalkSpecializes ⋯ ≫ Scheme.Hom.stalkMap g x

Tactic:
apply Spec.map_injective
    rw [← cancel_mono (Y.fromSpecStalk _)]
    simpa [Scheme.SpecMap_stalkSpecializes_fromSpecStalk]

Goal state after: