mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.RingTheory.RingHom.StandardSmooth

Goal state before:
pp: R : Type u
S : Type v
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
w✝² w✝¹ : Type
w✝ : _root_.Finite w✝¹
left✝ : _root_.Finite w✝²
P : Algebra.SubmersivePresentation R S w✝² w✝¹
this : Algebra R S := f.toAlgebra
⊢ ∃ n g, g.comp MvPolynomial.C = f ∧ g.Etale

Tactic:
exact ⟨_, RingHom.IsStandardSmoothOfRelativeDimension.exists_etale_mvPolynomial
    ⟨_, _, _, ‹_›, P, rfl⟩⟩

Goal state after:
Module: Mathlib.AlgebraicGeometry.EllipticCurve.Projective.Formula

Goal state before:
pp: F : Type u
inst✝ : Field F
W : Projective F
P Q : Fin 3 → F
hP : W.Equation P
hQ : W.Equation Q
hPz : P z ≠ 0
hQz : Q z ≠ 0
hx : P x * Q z = Q x * P z
⊢ W.negAddY P Q = -addU P Q

Tactic:
rw [addU, neg_div, neg_neg, ← mul_div_mul_right _ _ <| mul_ne_zero hPz hQz,
    ← negAddY_of_X_eq' hP hQ hx, ← sq,
    mul_div_cancel_right₀ _ <| pow_ne_zero 2 <| mul_ne_zero hPz hQz]

Goal state after:
Module: Mathlib.FieldTheory.SeparablyGenerated

Goal state before:
pp: k : Type u_1
K : Type u_2
ι : Type u_3
inst✝³ : Field k
inst✝² : Field K
inst✝¹ : Algebra k K
p : ℕ
hp : Nat.Prime p
H : ∀ (s : Finset K), LinearIndepOn k id ↑s → LinearIndepOn k (fun x ↦ x ^ p) ↑s
a : ι → K
inst✝ : ExpChar k p
s : Set ι
n : ι
ha : IsTranscendenceBasis k fun i ↦ a ↑i
hn : n ∉ s
e₁ : { j // j ≠ ⟨n, ⋯⟩ } ≃ ↑s :=
  { toFun := fun x ↦ ⟨↑↑x, ⋯⟩, invFun := fun x ↦ ⟨⟨↑x, ⋯⟩, ⋯⟩, left_inv := ⋯, right_inv := ⋯ }
i : ↑(insert n s)
hi : IsTranscendenceBasis k fun j ↦ a ↑↑j
hi' : IsSeparable (↥(adjoin k ((fun i ↦ a ↑i) '' {i}ᶜ))) (a ↑i)
e₂ : { j // j ≠ i } ≃ ↑(insert n s \ {↑i}) :=
  { toFun := fun x ↦ ⟨↑↑x, ⋯⟩, invFun := fun x ↦ ⟨⟨↑x, ⋯⟩, ⋯⟩, left_inv := ⋯, right_inv := ⋯ }
this : a '' (insert n s \ {↑i}) = (fun x ↦ a ↑x) '' {i}ᶜ
⊢ ∃ i, (IsTranscendenceBasis k fun j ↦ a ↑j) ∧ IsSeparable (↥(adjoin k (a '' (insert n s \ {i})))) (a i)

Tactic:
refine ⟨i, hi.comp_equiv e₂.symm, by convert! hi'⟩

Goal state after:
Module: Mathlib.FieldTheory.SeparablyGenerated

Goal state before:
pp: k : Type u_1
K : Type u_2
ι : Type u_3
inst✝³ : Field k
inst✝² : Field K
inst✝¹ : Algebra k K
p : ℕ
hp : Nat.Prime p
H : ∀ (s : Finset K), LinearIndepOn k id ↑s → LinearIndepOn k (fun x ↦ x ^ p) ↑s
a : ι → K
n : ι
inst✝ : ExpChar k p
ha : adjoin k (Set.range a) = ⊤
ha' : IsTranscendenceBasis k fun i ↦ a ↑i
i : ι
hi : (IsTranscendenceBasis k fun j ↦ a ↑j) ∧ IsSeparable (↥(adjoin k (a '' {i}ᶜ))) (a i)
⊢ restrictScalars k (separableClosure (↥(adjoin k (a '' {i}ᶜ))) K) = ⊤

Tactic:
eq_top_iff,

Goal state after:
k : Type u_1
K : Type u_2
ι : Type u_3
inst✝³ : Field k
inst✝² : Field K
inst✝¹ : Algebra k K
p : ℕ
hp : Nat.Prime p
H : ∀ (s : Finset K), LinearIndepOn k id ↑s → LinearIndepOn k (fun x ↦ x ^ p) ↑s
a : ι → K
n : ι
inst✝ : ExpChar k p
ha : adjoin k (Set.range a) = ⊤
ha' : IsTranscendenceBasis k fun i ↦ a ↑i
i : ι
hi : (IsTranscendenceBasis k fun j ↦ a ↑j) ∧ IsSeparable (↥(adjoin k (a '' {i}ᶜ))) (a i)
⊢ ⊤ ≤ restrictScalars k (separableClosure (↥(adjoin k (a '' {i}ᶜ))) K)
Module: Mathlib.FieldTheory.SeparablyGenerated

Goal state before:
pp: k : Type u_1
K : Type u_2
inst✝⁴ : Field k
inst✝³ : Field K
inst✝² : Algebra k K
p : ℕ
hp : Nat.Prime p
H : ∀ (s : Finset K), LinearIndepOn k id ↑s → LinearIndepOn k (fun x ↦ x ^ p) ↑s
inst✝¹ : ExpChar k p
inst✝ : Algebra.EssFiniteType k K
s : Finset K
hs : (fun t ↦ IsTranscendenceBasis k Subtype.val) ↑s
Hs :
  ∀ ⦃j : Set K⦄,
    (fun t ↦ IsTranscendenceBasis k Subtype.val) j →
      (fun t ↦ restrictScalars k (separableClosure (↥(adjoin k t)) K)) ↑s ≤
          (fun t ↦ restrictScalars k (separableClosure (↥(adjoin k t)) K)) j →
        (fun t ↦ restrictScalars k (separableClosure (↥(adjoin k t)) K)) j ≤
          (fun t ↦ restrictScalars k (separableClosure (↥(adjoin k t)) K)) ↑s
n : K
hn : ¬IsSeparable (↥(adjoin k ↑s)) n
hns : n ∉ s
i : K
hi₁ : IsTranscendenceBasis k fun j ↦ id ↑j
hi₂ : IsSeparable (↥(adjoin k (id '' (insert n ↑s \ {i})))) (id i)
⊢ False

Tactic:
rw [Set.image_id] at hi₂

Goal state after:
k : Type u_1
K : Type u_2
inst✝⁴ : Field k
inst✝³ : Field K
inst✝² : Algebra k K
p : ℕ
hp : Nat.Prime p
H : ∀ (s : Finset K), LinearIndepOn k id ↑s → LinearIndepOn k (fun x ↦ x ^ p) ↑s
inst✝¹ : ExpChar k p
inst✝ : Algebra.EssFiniteType k K
s : Finset K
hs : (fun t ↦ IsTranscendenceBasis k Subtype.val) ↑s
Hs :
  ∀ ⦃j : Set K⦄,
    (fun t ↦ IsTranscendenceBasis k Subtype.val) j →
      (fun t ↦ restrictScalars k (separableClosure (↥(adjoin k t)) K)) ↑s ≤
          (fun t ↦ restrictScalars k (separableClosure (↥(adjoin k t)) K)) j →
        (fun t ↦ restrictScalars k (separableClosure (↥(adjoin k t)) K)) j ≤
          (fun t ↦ restrictScalars k (separableClosure (↥(adjoin k t)) K)) ↑s
n : K
hn : ¬IsSeparable (↥(adjoin k ↑s)) n
hns : n ∉ s
i : K
hi₁ : IsTranscendenceBasis k fun j ↦ id ↑j
hi₂ : IsSeparable (↥(adjoin k (insert n ↑s \ {i}))) (id i)
⊢ False
Module: Mathlib.CategoryTheory.MorphismProperty.Descent

Goal state before:
pp: C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
P : MorphismProperty C
inst✝³ : (isomorphisms C).DescendsAlong P
inst✝² : P.IsStableUnderBaseChange
inst✝¹ : HasPullbacks C
inst✝ : HasEqualizers C
S T : C
f : T ⟶ S
hf : P f
X Y : Over S
a b : X ⟶ Y
hab : (Over.pullback f).map a = (Over.pullback f).map b
⊢ pullback.map X.hom f Y.hom f (Over.Hom.left a) (𝟙 T) (𝟙 S) ⋯ ⋯ =
    pullback.map X.hom f Y.hom f (Over.Hom.left b) (𝟙 T) (𝟙 S) ⋯ ⋯

Tactic:
convert! congr($(hab).left) <;> ext

Goal state after:
case e'_2.h₀
C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
P : MorphismProperty C
inst✝³ : (isomorphisms C).DescendsAlong P
inst✝² : P.IsStableUnderBaseChange
inst✝¹ : HasPullbacks C
inst✝ : HasEqualizers C
S T : C
f : T ⟶ S
hf : P f
X Y : Over S
a b : X ⟶ Y
hab : (Over.pullback f).map a = (Over.pullback f).map b
e_1✝ : (pullback X.hom f ⟶ pullback Y.hom f) = (((Over.pullback f).obj X).left ⟶ ((Over.pullback f).obj Y).left)
⊢ pullback.map X.hom f Y.hom f (Over.Hom.left a) (𝟙 T) (𝟙 S) ⋯ ⋯ ≫ pullback.fst Y.hom f =
    Over.Hom.left ((Over.pullback f).map a) ≫ pullback.fst Y.hom f

case h₁
C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
P : MorphismProperty C
inst✝³ : (isomorphisms C).DescendsAlong P
inst✝² : P.IsStableUnderBaseChange
inst✝¹ : HasPullbacks C
inst✝ : HasEqualizers C
S T : C
f : T ⟶ S
hf : P f
X Y : Over S
a b : X ⟶ Y
hab : (Over.pullback f).map a = (Over.pullback f).map b
e_1✝ : (pullback X.hom f ⟶ pullback Y.hom f) = (((Over.pullback f).obj X).left ⟶ ((Over.pullback f).obj Y).left)
⊢ pullback.map X.hom f Y.hom f (Over.Hom.left a) (𝟙 T) (𝟙 S) ⋯ ⋯ ≫ pullback.snd Y.hom f =
    Over.Hom.left ((Over.pullback f).map a) ≫ pullback.snd Y.hom f

case e'_3.h₀
C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
P : MorphismProperty C
inst✝³ : (isomorphisms C).DescendsAlong P
inst✝² : P.IsStableUnderBaseChange
inst✝¹ : HasPullbacks C
inst✝ : HasEqualizers C
S T : C
f : T ⟶ S
hf : P f
X Y : Over S
a b : X ⟶ Y
hab : (Over.pullback f).map a = (Over.pullback f).map b
e_1✝ : (pullback X.hom f ⟶ pullback Y.hom f) = (((Over.pullback f).obj X).left ⟶ ((Over.pullback f).obj Y).left)
⊢ pullback.map X.hom f Y.hom f (Over.Hom.left b) (𝟙 T) (𝟙 S) ⋯ ⋯ ≫ pullback.fst Y.hom f =
    Over.Hom.left ((Over.pullback f).map b) ≫ pullback.fst Y.hom f

case h₁
C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
P : MorphismProperty C
inst✝³ : (isomorphisms C).DescendsAlong P
inst✝² : P.IsStableUnderBaseChange
inst✝¹ : HasPullbacks C
inst✝ : HasEqualizers C
S T : C
f : T ⟶ S
hf : P f
X Y : Over S
a b : X ⟶ Y
hab : (Over.pullback f).map a = (Over.pullback f).map b
e_1✝ : (pullback X.hom f ⟶ pullback Y.hom f) = (((Over.pullback f).obj X).left ⟶ ((Over.pullback f).obj Y).left)
⊢ pullback.map X.hom f Y.hom f (Over.Hom.left b) (𝟙 T) (𝟙 S) ⋯ ⋯ ≫ pullback.snd Y.hom f =
    Over.Hom.left ((Over.pullback f).map b) ≫ pullback.snd Y.hom f
Module: Mathlib.RingTheory.IntegralClosure.IsIntegral.AlmostIntegral

Goal state before:
pp: R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
a b : S
r : R
hr : r ∈ R⁰
hr' : ∀ (n : ℕ), r • a ^ n ∈ (algebraMap R S).range
s : R
hs : s ∈ R⁰
hs' : ∀ (n : ℕ), s • b ^ n ∈ (algebraMap R S).range
n : ℕ
⊢ (r * s) • (a * b) ^ n ∈ (algebraMap R S).range

Tactic:
rw [mul_pow, mul_smul_mul_comm]

Goal state after:
R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
a b : S
r : R
hr : r ∈ R⁰
hr' : ∀ (n : ℕ), r • a ^ n ∈ (algebraMap R S).range
s : R
hs : s ∈ R⁰
hs' : ∀ (n : ℕ), s • b ^ n ∈ (algebraMap R S).range
n : ℕ
⊢ r • a ^ n * s • b ^ n ∈ (algebraMap R S).range
Module: Mathlib.RingTheory.IntegralClosure.IsIntegral.AlmostIntegral

Goal state before:
pp: R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
⊢ ∀ {a b : S}, a ∈ {s | IsAlmostIntegral R s} → b ∈ {s | IsAlmostIntegral R s} → a + b ∈ {s | IsAlmostIntegral R s}

Tactic:
by
    rintro a b ⟨r, hr, hr'⟩ ⟨s, hs, hs'⟩
    refine ⟨r * s, mul_mem hr hs, fun n ↦ ?_⟩
    simp only [add_pow, Finset.smul_sum, ← smul_mul_assoc _ (_ * _),
      ← smul_mul_smul_comm _ (a ^ _)]
    exact sum_mem fun i _ ↦ mul_mem (mul_mem (hr' _) (hs' _)) (by simp)

Goal state after:
Module: Mathlib.RingTheory.Valuation.IsTrivialOn

Goal state before:
pp: case neg
Γ : Type u_1
inst✝³ : LinearOrderedCommGroupWithZero Γ
A : Type u_2
inst✝² : CommSemiring A
B : Type u_3
inst✝¹ : Ring B
inst✝ : Algebra A B
v : Valuation B Γ
hv : Valuation.IsTrivialOn A v
w : B
hpos : 1 < v w
p : A[X]
hp : p ≠ 0
i : ℕ
hi : i < p.natDegree
h0 : ¬p.coeff i = 0
⊢ v ((algebraMap A B) (p.coeff i)) * v w ^ i < v ((algebraMap A B) p.leadingCoeff) * v w ^ p.natDegree

Tactic:
· simp [hv.eq_one p.leadingCoeff (leadingCoeff_ne_zero.mpr hp),
      hv.eq_one _ h0, pow_lt_pow_right₀ hpos hi]

Goal state after:
Module: Mathlib.RingTheory.Valuation.IsTrivialOn

Goal state before:
pp: case inr
Γ : Type u_1
inst✝³ : LinearOrderedCommGroupWithZero Γ
A : Type u_2
inst✝² : CommRing A
K : Type u_3
inst✝¹ : Field K
inst✝ : Algebra A K
v : Valuation K Γ
hv : IsTrivialOn A v
y : K
h0 : y ≠ 0
hy : v y ≠ 1
this : ∀ (y : K), y ≠ 0 → v y ≠ 1 → 1 < v y → Transcendental A y
hlt : v y ≤ 1
⊢ Transcendental A y

Tactic:
Transcendental,

Goal state after:
case inr
Γ : Type u_1
inst✝³ : LinearOrderedCommGroupWithZero Γ
A : Type u_2
inst✝² : CommRing A
K : Type u_3
inst✝¹ : Field K
inst✝ : Algebra A K
v : Valuation K Γ
hv : IsTrivialOn A v
y : K
h0 : y ≠ 0
hy : v y ≠ 1
this : ∀ (y : K), y ≠ 0 → v y ≠ 1 → 1 < v y → Transcendental A y
hlt : v y ≤ 1
⊢ ¬IsAlgebraic A y
Module: Mathlib.RingTheory.Polynomial.IsIntegral

Goal state before:
pp: R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
σ : Type w
f : MvPolynomial σ S
H : ∀ (n : σ →₀ ℕ), IsIntegral R (coeff n f)
⊢ IsIntegral (MvPolynomial σ R) f

Tactic:
rw [← f.support_sum_monomial_coeff]

Goal state after:
R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
σ : Type w
f : MvPolynomial σ S
H : ∀ (n : σ →₀ ℕ), IsIntegral R (coeff n f)
⊢ IsIntegral (MvPolynomial σ R) (∑ v ∈ f.support, (monomial v) (coeff v f))
Module: Mathlib.RingTheory.LocalRing.ResidueField.Polynomial

Goal state before:
pp: case refine_2
R : Type u_1
S : Type u_2
inst✝⁷ : CommRing R
inst✝⁶ : CommRing S
inst✝⁵ : Algebra R S
I : Ideal R
inst✝⁴ : I.IsPrime
J : Ideal R[X]
inst✝³ : J.IsPrime
inst✝² : J.LiesOver I
inst✝¹ : Algebra (Localization.AtPrime I) (Localization.AtPrime J)
inst✝ : Localization.AtPrime.IsLiesOverAlgebra I J
hJ : J = Ideal.map C I
f : J.ResidueField →+* RatFunc I.ResidueField :=
  Ideal.ResidueField.lift J
    ((algebraMap I.ResidueField[X] (RatFunc I.ResidueField)).comp (mapRingHom (algebraMap R I.ResidueField))) ⋯ ⋯
hf : f.comp (algebraMap I.ResidueField J.ResidueField) = algebraMap I.ResidueField (RatFunc I.ResidueField)
⊢ { toRingHom := f, commutes' := ⋯ }.comp (RatFunc.liftAlgHom (aeval ((algebraMap R[X] J.ResidueField) X)) ⋯) =
    AlgHom.id I.ResidueField (RatFunc I.ResidueField)

pp: case refine_3
R : Type u_1
S : Type u_2
inst✝⁷ : CommRing R
inst✝⁶ : CommRing S
inst✝⁵ : Algebra R S
I : Ideal R
inst✝⁴ : I.IsPrime
J : Ideal R[X]
inst✝³ : J.IsPrime
inst✝² : J.LiesOver I
inst✝¹ : Algebra (Localization.AtPrime I) (Localization.AtPrime J)
inst✝ : Localization.AtPrime.IsLiesOverAlgebra I J
hJ : J = Ideal.map C I
f : J.ResidueField →+* RatFunc I.ResidueField :=
  Ideal.ResidueField.lift J
    ((algebraMap I.ResidueField[X] (RatFunc I.ResidueField)).comp (mapRingHom (algebraMap R I.ResidueField))) ⋯ ⋯
hf : f.comp (algebraMap I.ResidueField J.ResidueField) = algebraMap I.ResidueField (RatFunc I.ResidueField)
⊢ (RatFunc.liftAlgHom (aeval ((algebraMap R[X] J.ResidueField) X)) ⋯).comp { toRingHom := f, commutes' := ⋯ } =
    AlgHom.id I.ResidueField J.ResidueField

Tactic:
· apply AlgHom.coe_ringHom_injective
    apply IsFractionRing.injective_comp_algebraMap (A := I.ResidueField[X])
    dsimp [RatFunc.liftAlgHom]
    simp only [AlgHom.comp_toRingHom, AlgHom.coe_ringHom_mk, RingHom.comp_assoc,
      RatFunc.liftRingHom_comp_algebraMap, RingHomCompTriple.comp_eq, f]
    ext <;> simp [← IsScalarTower.algebraMap_apply,
      IsScalarTower.algebraMap_apply R R[X] J.ResidueField]

Goal state after:
case refine_3
R : Type u_1
S : Type u_2
inst✝⁷ : CommRing R
inst✝⁶ : CommRing S
inst✝⁵ : Algebra R S
I : Ideal R
inst✝⁴ : I.IsPrime
J : Ideal R[X]
inst✝³ : J.IsPrime
inst✝² : J.LiesOver I
inst✝¹ : Algebra (Localization.AtPrime I) (Localization.AtPrime J)
inst✝ : Localization.AtPrime.IsLiesOverAlgebra I J
hJ : J = Ideal.map C I
f : J.ResidueField →+* RatFunc I.ResidueField :=
  Ideal.ResidueField.lift J
    ((algebraMap I.ResidueField[X] (RatFunc I.ResidueField)).comp (mapRingHom (algebraMap R I.ResidueField))) ⋯ ⋯
hf : f.comp (algebraMap I.ResidueField J.ResidueField) = algebraMap I.ResidueField (RatFunc I.ResidueField)
⊢ (RatFunc.liftAlgHom (aeval ((algebraMap R[X] J.ResidueField) X)) ⋯).comp { toRingHom := f, commutes' := ⋯ } =
    AlgHom.id I.ResidueField J.ResidueField
Module: Mathlib.RingTheory.QuasiFinite.Weakly

Goal state before:
pp: R : Type u_1
S : Type u_2
inst✝⁷ : CommRing R
inst✝⁶ : CommRing S
inst✝⁵ : Algebra R S
p : Ideal S
inst✝⁴ : p.IsPrime
inst✝³ : QuasiFiniteAt R (Ideal.map (Ideal.Quotient.mk (Ideal.map (algebraMap R S) (Ideal.under R p))) p)
A : Type u_4
inst✝² : CommRing A
inst✝¹ : Algebra R A
q : Ideal (A ⊗[R] S)
inst✝ : q.IsPrime
hq : p = Ideal.comap TensorProduct.includeRight.toRingHom q
φ : A ⊗[R] S →ₐ[A] (A ⧸ Ideal.under A q) ⊗[R] (S ⧸ Ideal.map (algebraMap R S) (Ideal.under R p)) :=
  TensorProduct.map (Ideal.Quotient.mkₐ A (Ideal.under A q))
    (Ideal.Quotient.mkₐ R (Ideal.map (algebraMap R S) (Ideal.under R p)))
hφ₁ : Function.Surjective ⇑φ
⊢ Ideal.map (algebraMap R (A ⊗[R] S)) (Ideal.comap (algebraMap R (A ⊗[R] S)) q) ≤
    Ideal.map (↑TensorProduct.includeLeft) (Ideal.comap (algebraMap A (A ⊗[R] S)) q)

Tactic:
simp only [← TensorProduct.includeLeft.comp_algebraMap, ← Ideal.map_map, ← Ideal.comap_comap]

Goal state after:
R : Type u_1
S : Type u_2
inst✝⁷ : CommRing R
inst✝⁶ : CommRing S
inst✝⁵ : Algebra R S
p : Ideal S
inst✝⁴ : p.IsPrime
inst✝³ : QuasiFiniteAt R (Ideal.map (Ideal.Quotient.mk (Ideal.map (algebraMap R S) (Ideal.under R p))) p)
A : Type u_4
inst✝² : CommRing A
inst✝¹ : Algebra R A
q : Ideal (A ⊗[R] S)
inst✝ : q.IsPrime
hq : p = Ideal.comap TensorProduct.includeRight.toRingHom q
φ : A ⊗[R] S →ₐ[A] (A ⧸ Ideal.under A q) ⊗[R] (S ⧸ Ideal.map (algebraMap R S) (Ideal.under R p)) :=
  TensorProduct.map (Ideal.Quotient.mkₐ A (Ideal.under A q))
    (Ideal.Quotient.mkₐ R (Ideal.map (algebraMap R S) (Ideal.under R p)))
hφ₁ : Function.Surjective ⇑φ
⊢ Ideal.map (↑TensorProduct.includeLeft)
      (Ideal.map (algebraMap R A) (Ideal.comap (algebraMap R A) (Ideal.comap (↑TensorProduct.includeLeft) q))) ≤
    Ideal.map (↑TensorProduct.includeLeft) (Ideal.comap (algebraMap A A) (Ideal.comap (↑TensorProduct.includeLeft) q))
Module: Mathlib.RingTheory.QuasiFinite.Weakly

Goal state before:
pp: R : Type u_1
S : Type u_2
T : Type u_3
inst✝⁸ : CommRing R
inst✝⁷ : CommRing S
inst✝⁶ : Algebra R S
inst✝⁵ : CommRing T
inst✝⁴ : Algebra R T
inst✝³ : Algebra S T
inst✝² : IsScalarTower R S T
q : Ideal T
inst✝¹ : q.IsPrime
inst✝ : WeaklyQuasiFiniteAt R q
this : QuasiFiniteAt S (Ideal.map (Ideal.Quotient.mk (Ideal.map (algebraMap R T) (Ideal.under R q))) q)
⊢ Ideal.map (algebraMap R T) (Ideal.under R q) ≤ Ideal.map (algebraMap S T) (Ideal.under S q)

Tactic:
simpa [Ideal.under, IsScalarTower.algebraMap_eq R S T, ← Ideal.map_map,
      ← Ideal.comap_comap, -Ideal.under_under] using Ideal.map_mono Ideal.map_comap_le

Goal state after:
Module: Mathlib.RingTheory.LocalRing.ResidueField.Polynomial

Goal state before:
pp: R : Type u_1
inst✝¹ : CommRing R
P : Ideal R
inst✝ : P.IsPrime
I : Ideal R[X]
p : P.ResidueField[X]
hp : Ideal.map (mapRingHom (algebraMap R P.ResidueField)) I = Ideal.span {p}
this✝¹ : Algebra (R ⧸ P)[X] P.ResidueField[X] := (mapRingHom (algebraMap (R ⧸ P) P.ResidueField)).toAlgebra
this✝ : IsLocalization (Submonoid.map C (R ⧸ P)⁰) P.ResidueField[X]
this : p ∈ Ideal.map (algebraMap (R ⧸ P)[X] P.ResidueField[X]) (Ideal.map (mapRingHom (algebraMap R (R ⧸ P))) I)
s : ↥(Submonoid.map C (R ⧸ P)⁰)
r : (R ⧸ P)[X]
hr : r ∈ Ideal.map (mapRingHom (algebraMap R (R ⧸ P))) I
e :
  p * (algebraMap (R ⧸ P)[X] P.ResidueField[X]) ↑(⟨r, hr⟩, s).2 =
    (algebraMap (R ⧸ P)[X] P.ResidueField[X]) ↑(⟨r, hr⟩, s).1
⊢ ∃ p ∈ I, Ideal.span {map (algebraMap R P.ResidueField) p} = Ideal.map (mapRingHom (algebraMap R P.ResidueField)) I

Tactic:
obtain ⟨r, hr', rfl⟩ := (Ideal.mem_map_iff_of_surjective _
    (Polynomial.map_surjective _ Ideal.Quotient.mk_surjective)).mp hr

Goal state after:
R : Type u_1
inst✝¹ : CommRing R
P : Ideal R
inst✝ : P.IsPrime
I : Ideal R[X]
p : P.ResidueField[X]
hp : Ideal.map (mapRingHom (algebraMap R P.ResidueField)) I = Ideal.span {p}
this✝¹ : Algebra (R ⧸ P)[X] P.ResidueField[X] := (mapRingHom (algebraMap (R ⧸ P) P.ResidueField)).toAlgebra
this✝ : IsLocalization (Submonoid.map C (R ⧸ P)⁰) P.ResidueField[X]
this : p ∈ Ideal.map (algebraMap (R ⧸ P)[X] P.ResidueField[X]) (Ideal.map (mapRingHom (algebraMap R (R ⧸ P))) I)
s : ↥(Submonoid.map C (R ⧸ P)⁰)
r : R[X]
hr' : r ∈ I
hr : (mapRingHom (algebraMap R (R ⧸ P))) r ∈ Ideal.map (mapRingHom (algebraMap R (R ⧸ P))) I
e :
  p * (algebraMap (R ⧸ P)[X] P.ResidueField[X]) ↑(⟨(mapRingHom (algebraMap R (R ⧸ P))) r, hr⟩, s).2 =
    (algebraMap (R ⧸ P)[X] P.ResidueField[X]) ↑(⟨(mapRingHom (algebraMap R (R ⧸ P))) r, hr⟩, s).1
⊢ ∃ p ∈ I, Ideal.span {map (algebraMap R P.ResidueField) p} = Ideal.map (mapRingHom (algebraMap R P.ResidueField)) I
Module: Mathlib.AlgebraicGeometry.Morphisms.QuasiFinite

Goal state before:
pp: case inr
X Y : Scheme
f : X ⟶ Y
inst✝ : LocallyOfFiniteType f
x : ↥X
this :
  ∀ {X Y : Scheme} {f : X ⟶ Y} [LocallyOfFiniteType f] {x : ↥X},
    (∃ R, Y = Spec R) → (QuasiFiniteAt f x ↔ IsOpen {⟨x, ⋯⟩})
hY : ¬∃ R, Y = Spec R
⊢ QuasiFiniteAt f x ↔ IsOpen {⟨x, ⋯⟩}

Tactic:
obtain ⟨i, y, hy⟩ := Y.affineCover.exists_eq (f x)

Goal state after:
case inr
X Y : Scheme
f : X ⟶ Y
inst✝ : LocallyOfFiniteType f
x : ↥X
this :
  ∀ {X Y : Scheme} {f : X ⟶ Y} [LocallyOfFiniteType f] {x : ↥X},
    (∃ R, Y = Spec R) → (QuasiFiniteAt f x ↔ IsOpen {⟨x, ⋯⟩})
hY : ¬∃ R, Y = Spec R
i : Y.affineCover.I₀
y : ↥(Y.affineCover.X i)
hy : (Y.affineCover.f i) y = f x
⊢ QuasiFiniteAt f x ↔ IsOpen {⟨x, ⋯⟩}
Module: Mathlib.RingTheory.Etale.StandardEtale

Goal state before:
pp: case refine_2
R : Type u_1
S : Type u_2
T : Type u_3
inst✝⁴ : CommRing R
inst✝³ : CommRing S
inst✝² : CommRing T
inst✝¹ : Algebra R S
inst✝ : Algebra R T
P : StandardEtalePair R
⊢ IsUnit ((algebraMap (AdjoinRoot P.f) (Localization.Away ((AdjoinRoot.mk P.f) P.g))) ((AdjoinRoot.mk P.f) P.g))

Tactic:
exact IsLocalization.Away.algebraMap_isUnit ..

Goal state after:
Module: Mathlib.RingTheory.Etale.StandardEtale

Goal state before:
pp: R : Type u_1
S : Type u_2
T : Type u_3
inst✝⁴ : CommRing R
inst✝³ : CommRing S
inst✝² : CommRing T
inst✝¹ : Algebra R S
inst✝ : Algebra R T
P✝ : StandardEtalePair R
P : StandardEtalePresentation R S
⊢ Ideal.span (Set.range ![(Bivariate.equivMvPolynomial R) (C P.f), (Bivariate.equivMvPolynomial R) (Y * C P.g - 1)]) =
    (Algebra.Generators.ofAlgHom
        ((P.lift P.x ⋯).comp
          ((↑P.equivMvPolynomialQuotient.symm).comp
            (Ideal.Quotient.mkₐ R
              (Ideal.span {(Bivariate.equivMvPolynomial R) (C P.f), (Bivariate.equivMvPolynomial R) (Y * C P.g - 1)}))))
        ⋯).ker

Tactic:
rw [Algebra.Generators.ker_ofAlgHom, AlgHom.toRingHom_eq_coe, AlgHom.comp_toRingHom,
      AlgHom.comp_toRingHom,
      RingHom.ker_comp_of_injective _ (by exact P.lift_bijective.injective),
      RingHom.ker_comp_of_injective _ (by exact P.equivMvPolynomialQuotient.symm.injective)]

Goal state after:
R : Type u_1
S : Type u_2
T : Type u_3
inst✝⁴ : CommRing R
inst✝³ : CommRing S
inst✝² : CommRing T
inst✝¹ : Algebra R S
inst✝ : Algebra R T
P✝ : StandardEtalePair R
P : StandardEtalePresentation R S
⊢ Ideal.span (Set.range ![(Bivariate.equivMvPolynomial R) (C P.f), (Bivariate.equivMvPolynomial R) (Y * C P.g - 1)]) =
    RingHom.ker
      ↑(Ideal.Quotient.mkₐ R
          (Ideal.span {(Bivariate.equivMvPolynomial R) (C P.f), (Bivariate.equivMvPolynomial R) (Y * C P.g - 1)}))
Module: Mathlib.RingTheory.Smooth.IntegralClosure

Goal state before:
pp: R : Type u_1
B : Type u_3
inst✝² : CommRing R
inst✝¹ : CommRing B
inst✝ : Algebra R B
σ : Type u_4
x : MvPolynomial σ R ⊗[R] B
hx : x ∈ integralClosure (MvPolynomial σ R) (MvPolynomial σ R ⊗[R] B)
e₀ : MvPolynomial σ R ⊗[R] B ≃ₐ[R] MvPolynomial σ B :=
  (Algebra.TensorProduct.comm R (MvPolynomial σ R) B).trans
    (AlgEquiv.restrictScalars R (MvPolynomial.algebraTensorAlgEquiv R B))
e₁ : MvPolynomial σ R ⊗[R] ↥(integralClosure R B) ≃ₐ[R] MvPolynomial σ ↥(integralClosure R B) :=
  (Algebra.TensorProduct.comm R (MvPolynomial σ R) ↥(integralClosure R B)).trans
    (AlgEquiv.restrictScalars R (MvPolynomial.algebraTensorAlgEquiv R ↥(integralClosure R B)))
e : MvPolynomial σ R ⊗[R] B ≃ₐ[MvPolynomial σ R] MvPolynomial σ B :=
  let __RingEquiv := e₀.toRingEquiv;
  { toEquiv := __RingEquiv.toEquiv, map_mul' := ⋯, map_add' := ⋯, commutes' := ⋯ }
this : ∀ (n : σ →₀ ℕ), IsIntegral R (MvPolynomial.coeff n (e x))
y : MvPolynomial σ R ⊗[R] ↥(integralClosure R B)
hy : (MvPolynomial.map (integralClosure R B).val.toRingHom) (e₁ y) = e x
⊢ e₀ ((Algebra.TensorProduct.map (AlgHom.id (MvPolynomial σ R) (MvPolynomial σ R)) (integralClosure R B).val) y) =
    (MvPolynomial.map ↑(integralClosure R B).val) (e₁ y)

Tactic:
have : e₀.toAlgHom.comp
      (Algebra.TensorProduct.map (AlgHom.id R (MvPolynomial σ R)) (integralClosure R B).val) =
      (MvPolynomial.mapAlgHom (integralClosure R B).val).comp e₁.toAlgHom := by
    ext <;> simp [e₀, e₁, MvPolynomial.coeff_map, MvPolynomial.coeff_one,
      apply_ite ((↑) : (integralClosure R B) → B)]

Goal state after:
R : Type u_1
B : Type u_3
inst✝² : CommRing R
inst✝¹ : CommRing B
inst✝ : Algebra R B
σ : Type u_4
x : MvPolynomial σ R ⊗[R] B
hx : x ∈ integralClosure (MvPolynomial σ R) (MvPolynomial σ R ⊗[R] B)
e₀ : MvPolynomial σ R ⊗[R] B ≃ₐ[R] MvPolynomial σ B :=
  (Algebra.TensorProduct.comm R (MvPolynomial σ R) B).trans
    (AlgEquiv.restrictScalars R (MvPolynomial.algebraTensorAlgEquiv R B))
e₁ : MvPolynomial σ R ⊗[R] ↥(integralClosure R B) ≃ₐ[R] MvPolynomial σ ↥(integralClosure R B) :=
  (Algebra.TensorProduct.comm R (MvPolynomial σ R) ↥(integralClosure R B)).trans
    (AlgEquiv.restrictScalars R (MvPolynomial.algebraTensorAlgEquiv R ↥(integralClosure R B)))
e : MvPolynomial σ R ⊗[R] B ≃ₐ[MvPolynomial σ R] MvPolynomial σ B :=
  let __RingEquiv := e₀.toRingEquiv;
  { toEquiv := __RingEquiv.toEquiv, map_mul' := ⋯, map_add' := ⋯, commutes' := ⋯ }
this✝ : ∀ (n : σ →₀ ℕ), IsIntegral R (MvPolynomial.coeff n (e x))
y : MvPolynomial σ R ⊗[R] ↥(integralClosure R B)
hy : (MvPolynomial.map (integralClosure R B).val.toRingHom) (e₁ y) = e x
this :
  (↑e₀).comp (Algebra.TensorProduct.map (AlgHom.id R (MvPolynomial σ R)) (integralClosure R B).val) =
    (MvPolynomial.mapAlgHom (integralClosure R B).val).comp ↑e₁
⊢ e₀ ((Algebra.TensorProduct.map (AlgHom.id (MvPolynomial σ R) (MvPolynomial σ R)) (integralClosure R B).val) y) =
    (MvPolynomial.map ↑(integralClosure R B).val) (e₁ y)