mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.RingTheory.Invariant.Basic

Goal state before:
pp: case refine_2
B : Type u_2
inst✝⁴ : CommRing B
G : Type u_3
inst✝³ : Group G
inst✝² : Finite G
inst✝¹ : MulSemiringAction G B
Q : Ideal B
inst✝ : Q.IsPrime
val✝ : Fintype G
P : Ideal B := {g | g • Q ≠ Q}.inf fun g ↦ g • Q
h1 : ¬P ≤ Q
b : B
hbQ : b ∉ Q
hbP : ∀ (g : G), g • Q ≠ Q → b ∈ g • Q
f : B[X] := MulSemiringAction.charpoly G b
q : (B ⧸ Q)[X]
hq : map (algebraMap B (B ⧸ Q)) f = X ^ rootMultiplicity 0 (map (algebraMap B (B ⧸ Q)) f) * q
hq0 : ¬X ∣ q
j : ℕ := rootMultiplicity 0 (map (algebraMap B (B ⧸ Q)) f)
k : ℕ := q.natDegree
r : B[X] := ∑ i ∈ Finset.range (k + 1), (monomial i) (f.coeff (i + j))
hr✝ : map (algebraMap B (B ⧸ Q)) r = q
hf : eval b f = 0
hr : eval b r ∈ Q
a : B := f.coeff j
ha : ∀ (g : G), g • a = a
hr' : ∀ (g : G), g • Q ≠ Q → a - eval b r ∈ g • Q
h : G
⊢ (algebraMap B (B ⧸ Q)) (h • (a - eval b r) - if h • Q = Q then a else 0) = 0

Tactic:
Ideal.Quotient.algebraMap_eq,

Goal state after:
case refine_2
B : Type u_2
inst✝⁴ : CommRing B
G : Type u_3
inst✝³ : Group G
inst✝² : Finite G
inst✝¹ : MulSemiringAction G B
Q : Ideal B
inst✝ : Q.IsPrime
val✝ : Fintype G
P : Ideal B := {g | g • Q ≠ Q}.inf fun g ↦ g • Q
h1 : ¬P ≤ Q
b : B
hbQ : b ∉ Q
hbP : ∀ (g : G), g • Q ≠ Q → b ∈ g • Q
f : B[X] := MulSemiringAction.charpoly G b
q : (B ⧸ Q)[X]
hq : map (algebraMap B (B ⧸ Q)) f = X ^ rootMultiplicity 0 (map (algebraMap B (B ⧸ Q)) f) * q
hq0 : ¬X ∣ q
j : ℕ := rootMultiplicity 0 (map (algebraMap B (B ⧸ Q)) f)
k : ℕ := q.natDegree
r : B[X] := ∑ i ∈ Finset.range (k + 1), (monomial i) (f.coeff (i + j))
hr✝ : map (algebraMap B (B ⧸ Q)) r = q
hf : eval b f = 0
hr : eval b r ∈ Q
a : B := f.coeff j
ha : ∀ (g : G), g • a = a
hr' : ∀ (g : G), g • Q ≠ Q → a - eval b r ∈ g • Q
h : G
⊢ (Ideal.Quotient.mk Q) (h • (a - eval b r) - if h • Q = Q then a else 0) = 0
Module: Mathlib.RingTheory.Trace.Basic

Goal state before:
pp: case neg.succ.hnc
K : Type u_4
L : Type u_5
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
H : ¬Algebra.IsSeparable K L
p : ℕ
hp : ExpChar K p
this : p ≠ 0
x : L
h₀ : FiniteDimensional K L
hx : ¬IsSeparable K x
g : K[X]
hg₁ : g.Separable
n : ℕ
hg₂ : (expand K (p ^ (n + 1))) g = minpoly K x
⊢ ¬p ^ (n + 1) ∣ ((expand K (p ^ (n + 1))) g).natDegree - 1

Tactic:
rw [natDegree_expand]

Goal state after:
case neg.succ.hnc
K : Type u_4
L : Type u_5
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
H : ¬Algebra.IsSeparable K L
p : ℕ
hp : ExpChar K p
this : p ≠ 0
x : L
h₀ : FiniteDimensional K L
hx : ¬IsSeparable K x
g : K[X]
hg₁ : g.Separable
n : ℕ
hg₂ : (expand K (p ^ (n + 1))) g = minpoly K x
⊢ ¬p ^ (n + 1) ∣ g.natDegree * p ^ (n + 1) - 1
Module: Mathlib.FieldTheory.Galois.IsGaloisGroup

Goal state before:
pp: case inl
G : Type u_1
K : Type u_3
L : Type u_4
inst✝⁵ : Group G
inst✝⁴ : Field K
inst✝³ : Field L
inst✝² : Algebra K L
inst✝¹ : MulSemiringAction G L
inst✝ : IsGaloisGroup G K L
val✝ : Fintype G
this : FaithfulSMul G L
⊢ Nat.card G = finrank (↥⊥) L

Tactic:
← fixedPoints_eq_bot G,

Goal state after:
case inl
G : Type u_1
K : Type u_3
L : Type u_4
inst✝⁵ : Group G
inst✝⁴ : Field K
inst✝³ : Field L
inst✝² : Algebra K L
inst✝¹ : MulSemiringAction G L
inst✝ : IsGaloisGroup G K L
val✝ : Fintype G
this : FaithfulSMul G L
⊢ Nat.card G = finrank (↥(FixedPoints.intermediateField G)) L
Module: Mathlib.FieldTheory.Galois.IsGaloisGroup

Goal state before:
pp: G : Type u_1
inst✝⁷ : Group G
R : Type u_5
B : Type u_6
inst✝⁶ : CommRing R
inst✝⁵ : CommRing B
inst✝⁴ : Algebra R B
inst✝³ : Module.Finite R B
inst✝² : IsDomain B
inst✝¹ : MulSemiringAction G B
inst✝ : IsGaloisGroup G R B
A : Subring B := (algebraMap R B).range
this✝² : Algebra (FractionRing ↥A) (FractionRing B) := FractionRing.liftAlgebra (↥A) (FractionRing B)
this✝¹ : MulSemiringAction G (FractionRing B) := IsFractionRing.mulSemiringAction G B (FractionRing B)
this✝ : Algebra R ↥A := (algebraMap R B).rangeRestrict.toAlgebra
this : IsScalarTower R (↥A) B
⊢ Finite G

Tactic:
have : Module.Finite A B := Module.Finite.of_restrictScalars_finite R A B

Goal state after:
G : Type u_1
inst✝⁷ : Group G
R : Type u_5
B : Type u_6
inst✝⁶ : CommRing R
inst✝⁵ : CommRing B
inst✝⁴ : Algebra R B
inst✝³ : Module.Finite R B
inst✝² : IsDomain B
inst✝¹ : MulSemiringAction G B
inst✝ : IsGaloisGroup G R B
A : Subring B := (algebraMap R B).range
this✝³ : Algebra (FractionRing ↥A) (FractionRing B) := FractionRing.liftAlgebra (↥A) (FractionRing B)
this✝² : MulSemiringAction G (FractionRing B) := IsFractionRing.mulSemiringAction G B (FractionRing B)
this✝¹ : Algebra R ↥A := (algebraMap R B).rangeRestrict.toAlgebra
this✝ : IsScalarTower R (↥A) B
this : Module.Finite (↥A) B
⊢ Finite G
Module: Mathlib.FieldTheory.Galois.IsGaloisGroup

Goal state before:
pp: G : Type u_1
G' : Type u_2
inst✝¹² : Group G
inst✝¹¹ : Group G'
A : Type u_5
B : Type u_6
inst✝¹⁰ : CommRing A
inst✝⁹ : CommRing B
inst✝⁸ : IsDomain B
inst✝⁷ : Algebra A B
inst✝⁶ : FaithfulSMul A B
inst✝⁵ : MulSemiringAction G B
inst✝⁴ : MulSemiringAction G' B
inst✝³ : IsGaloisGroup G A B
inst✝² : IsGaloisGroup G' A B
inst✝¹ : Finite G
inst✝ : Finite G'
S : Set B
⊢ Subgroup.map (↑(mulEquivCongr G G' A B)) (fixingSubgroup G S) = fixingSubgroup G' S

Tactic:
by
  ext g
  simp [Subgroup.map_equiv_eq_comap_symm, mem_fixingSubgroup_iff]

Goal state after:
Module: Mathlib.RingTheory.Trace.Basic

Goal state before:
pp: K : Type u_4
L : Type u_5
inst✝⁷ : Field K
inst✝⁶ : Field L
inst✝⁵ : Algebra K L
κ : Type w
E : Type z
inst✝⁴ : Field E
inst✝³ : Algebra K E
inst✝² : Module.Finite K L
inst✝¹ : Algebra.IsSeparable K L
inst✝ : IsAlgClosed E
b : κ → L
i j : κ
⊢ (traceMatrix K b).map (⇑(algebraMap K E)) i j = (embeddingsMatrix K E b * (embeddingsMatrix K E b)ᵀ) i j

Tactic:
simp [trace_eq_sum_embeddings, embeddingsMatrix, Matrix.mul_apply]

Goal state after:
Module: Mathlib.RingTheory.Trace.Basic

Goal state before:
pp: K : Type u_4
L : Type u_5
inst✝³ : Field K
inst✝² : Field L
inst✝¹ : Algebra K L
pb : PowerBasis K L
inst✝ : Algebra.IsSeparable K L
this : (algebraMap K (AlgebraicClosure L)) (traceMatrix K ⇑pb.basis).det ≠ 0
ht : (traceMatrix K ⇑pb.basis).det = 0
⊢ (algebraMap K (AlgebraicClosure L)) (traceMatrix K ⇑pb.basis).det = 0

Tactic:
ht,

Goal state after:
K : Type u_4
L : Type u_5
inst✝³ : Field K
inst✝² : Field L
inst✝¹ : Algebra K L
pb : PowerBasis K L
inst✝ : Algebra.IsSeparable K L
this : (algebraMap K (AlgebraicClosure L)) (traceMatrix K ⇑pb.basis).det ≠ 0
ht : (traceMatrix K ⇑pb.basis).det = 0
⊢ (algebraMap K (AlgebraicClosure L)) 0 = 0
Module: Mathlib.FieldTheory.Finite.Basic

Goal state before:
pp: K : Type u_1
inst✝² : Field K
inst✝¹ : Fintype K
inst✝ : DecidableEq K
i : ℕ
φ : Kˣ →* K := { toFun := fun x ↦ ↑x ^ i, map_one' := ⋯, map_mul' := ⋯ }
this : Decidable (φ = 1)
⊢ ↑(if φ = 1 then Fintype.card Kˣ else 0) = if q - 1 ∣ i then -1 else 0

Tactic:
suffices q - 1 ∣ i ↔ φ = 1 by
          simp only [this]
          split_ifs; swap
          · exact Nat.cast_zero
          · rw [Fintype.card_units, Nat.cast_sub,
              cast_card_eq_zero, Nat.cast_one, zero_sub]
            show 1 ≤ q; exact Fintype.card_pos_iff.mpr ⟨0⟩

Goal state after:
K : Type u_1
inst✝² : Field K
inst✝¹ : Fintype K
inst✝ : DecidableEq K
i : ℕ
φ : Kˣ →* K := { toFun := fun x ↦ ↑x ^ i, map_one' := ⋯, map_mul' := ⋯ }
this : Decidable (φ = 1)
⊢ q - 1 ∣ i ↔ φ = 1
Module: Mathlib.RingTheory.Invariant.Basic

Goal state before:
pp: case intro
A : Type u_1
B : Type u_2
inst✝¹⁸ : CommRing A
inst✝¹⁷ : CommRing B
inst✝¹⁶ : Algebra A B
G : Type u_3
inst✝¹⁵ : Group G
inst✝¹⁴ : Finite G
inst✝¹³ : MulSemiringAction G B
inst✝¹² : SMulCommClass G A B
P : Ideal A
Q : Ideal B
inst✝¹¹ : Q.IsPrime
inst✝¹⁰ : Q.LiesOver P
K : Type u_4
L : Type u_5
inst✝⁹ : Field K
inst✝⁸ : Field L
inst✝⁷ : Algebra (A ⧸ P) K
inst✝⁶ : Algebra (B ⧸ Q) L
inst✝⁵ : Algebra (A ⧸ P) L
inst✝⁴ : IsScalarTower (A ⧸ P) (B ⧸ Q) L
inst✝³ : Algebra K L
inst✝² : IsScalarTower (A ⧸ P) K L
inst✝¹ : Algebra.IsInvariant A B G
inst✝ : Module.IsTorsionFree (B ⧸ Q) L
f : Gal(L/K)
val✝ : Fintype G
b₀ : B
hx :
  ∀ (g : ↥(MulAction.stabilizer G Q)),
    ((Ideal.Quotient.stabilizerHom Q P G) g) ((Ideal.Quotient.mk Q) b₀) = (Ideal.Quotient.mk Q) b₀
b : B
M : A[X]
a : A
ha1 : ∀ (g : G), g • (algebraMap A B) a = (algebraMap A B) a
ha2 : (algebraMap A B) a ∉ Q
hb :
  ∀ (g : G), (algebraMap B (B ⧸ Q)) (g • b) = (algebraMap B (B ⧸ Q)) (if g • Q = Q then (algebraMap A B) a * b₀ else 0)
key₀ :
  ∀ (g : G),
    map (algebraMap B (B ⧸ Q)) (X - C (g • b)) =
      if g • Q = Q then X - C ((algebraMap B (B ⧸ Q)) ((algebraMap A B) a * b₀)) else X
key :
  (algebraMap K L) ((algebraMap (A ⧸ P) K) ((algebraMap A (A ⧸ P)) a)) *
      f ((algebraMap (B ⧸ Q) L) ((algebraMap B (B ⧸ Q)) b₀)) =
    (algebraMap K L) ((algebraMap (A ⧸ P) K) ((algebraMap A (A ⧸ P)) a)) *
      (algebraMap (B ⧸ Q) L) ((algebraMap B (B ⧸ Q)) b₀)
⊢ ¬(algebraMap B (B ⧸ Q)) ((algebraMap A B) a) = 0

Tactic:
Ideal.Quotient.algebraMap_eq,

Goal state after:
case intro
A : Type u_1
B : Type u_2
inst✝¹⁸ : CommRing A
inst✝¹⁷ : CommRing B
inst✝¹⁶ : Algebra A B
G : Type u_3
inst✝¹⁵ : Group G
inst✝¹⁴ : Finite G
inst✝¹³ : MulSemiringAction G B
inst✝¹² : SMulCommClass G A B
P : Ideal A
Q : Ideal B
inst✝¹¹ : Q.IsPrime
inst✝¹⁰ : Q.LiesOver P
K : Type u_4
L : Type u_5
inst✝⁹ : Field K
inst✝⁸ : Field L
inst✝⁷ : Algebra (A ⧸ P) K
inst✝⁶ : Algebra (B ⧸ Q) L
inst✝⁵ : Algebra (A ⧸ P) L
inst✝⁴ : IsScalarTower (A ⧸ P) (B ⧸ Q) L
inst✝³ : Algebra K L
inst✝² : IsScalarTower (A ⧸ P) K L
inst✝¹ : Algebra.IsInvariant A B G
inst✝ : Module.IsTorsionFree (B ⧸ Q) L
f : Gal(L/K)
val✝ : Fintype G
b₀ : B
hx :
  ∀ (g : ↥(MulAction.stabilizer G Q)),
    ((Ideal.Quotient.stabilizerHom Q P G) g) ((Ideal.Quotient.mk Q) b₀) = (Ideal.Quotient.mk Q) b₀
b : B
M : A[X]
a : A
ha1 : ∀ (g : G), g • (algebraMap A B) a = (algebraMap A B) a
ha2 : (algebraMap A B) a ∉ Q
hb :
  ∀ (g : G), (algebraMap B (B ⧸ Q)) (g • b) = (algebraMap B (B ⧸ Q)) (if g • Q = Q then (algebraMap A B) a * b₀ else 0)
key₀ :
  ∀ (g : G),
    map (algebraMap B (B ⧸ Q)) (X - C (g • b)) =
      if g • Q = Q then X - C ((algebraMap B (B ⧸ Q)) ((algebraMap A B) a * b₀)) else X
key :
  (algebraMap K L) ((algebraMap (A ⧸ P) K) ((algebraMap A (A ⧸ P)) a)) *
      f ((algebraMap (B ⧸ Q) L) ((algebraMap B (B ⧸ Q)) b₀)) =
    (algebraMap K L) ((algebraMap (A ⧸ P) K) ((algebraMap A (A ⧸ P)) a)) *
      (algebraMap (B ⧸ Q) L) ((algebraMap B (B ⧸ Q)) b₀)
⊢ ¬(Ideal.Quotient.mk Q) ((algebraMap A B) a) = 0
Module: Mathlib.RingTheory.Invariant.Basic

Goal state before:
pp: case hg
A : Type u_1
B : Type u_2
inst✝¹⁶ : CommRing A
inst✝¹⁵ : CommRing B
inst✝¹⁴ : Algebra A B
G : Type u_3
inst✝¹³ : Group G
inst✝¹² : MulSemiringAction G B
inst✝¹¹ : SMulCommClass G A B
P : Ideal A
Q : Ideal B
inst✝¹⁰ : Q.LiesOver P
K : Type u_4
L : Type u_5
inst✝⁹ : Field K
inst✝⁸ : Field L
inst✝⁷ : Algebra (A ⧸ P) K
inst✝⁶ : Algebra (B ⧸ Q) L
inst✝⁵ : Algebra (A ⧸ P) L
inst✝⁴ : IsScalarTower (A ⧸ P) (B ⧸ Q) L
inst✝³ : Algebra K L
inst✝² : IsScalarTower (A ⧸ P) K L
inst✝¹ : IsFractionRing (A ⧸ P) K
inst✝ : IsFractionRing (B ⧸ Q) L
⊢ Function.Injective ⇑(fieldEquivOfAlgEquivHom K L)

Tactic:
apply fieldEquivOfAlgEquivHom_injective

Goal state after:
Module: Mathlib.FieldTheory.Finite.Basic

Goal state before:
pp: F : Type u_3
inst✝¹ : Field F
inst✝ : Fintype F
hF : ringChar F ≠ 2
g : Fˣ
hg : ∀ (x : Fˣ), x ∈ Subgroup.zpowers g
n : ℕ
hodd : 2 * (Nat.card F / 2) = Nat.card F - 1
h : (fun x ↦ g ^ x) n ^ (Nat.card F / 2) = 1
⊢ 2 * (Nat.card F / 2) ∣ n * (Nat.card F / 2)

Tactic:
← pow_mul

Goal state after:
F : Type u_3
inst✝¹ : Field F
inst✝ : Fintype F
hF : ringChar F ≠ 2
g : Fˣ
hg : ∀ (x : Fˣ), x ∈ Subgroup.zpowers g
n : ℕ
hodd : 2 * (Nat.card F / 2) = Nat.card F - 1
h : g ^ (n * (Nat.card F / 2)) = 1
⊢ 2 * (Nat.card F / 2) ∣ n * (Nat.card F / 2)
Module: Mathlib.RingTheory.Invariant.Basic

Goal state before:
pp: case h
G : Type u_1
A : Type u_2
B : Type u_3
K : Type u_4
L : Type u_5
inst✝¹⁸ : Group G
inst✝¹⁷ : CommRing A
inst✝¹⁶ : CommRing B
inst✝¹⁵ : Algebra A B
inst✝¹⁴ : Field K
inst✝¹³ : Field L
inst✝¹² : Algebra K L
inst✝¹¹ : Algebra A K
inst✝¹⁰ : Algebra B L
inst✝⁹ : Algebra A L
inst✝⁸ : IsFractionRing A K
inst✝⁷ : IsFractionRing B L
inst✝⁶ : IsScalarTower A K L
inst✝⁵ : IsScalarTower A B L
inst✝⁴ : MulSemiringAction G B
inst✝³ : MulSemiringAction G L
inst✝² : SMulDistribClass G B L
hAB : Algebra.IsInvariant A B G
inst✝¹ : SMulCommClass G A B
inst✝ : Algebra.IsIntegral A B
hc : ∀ (a : A), (algebraMap K L) ((algebraMap A K) a) = (algebraMap B L) ((algebraMap A B) a)
this✝ : Nontrivial A
this : Nontrivial B
x y : B
hy : y ∈ nonZeroDivisors B
h : ∀ (g : G), g • ((algebraMap B L) x / (algebraMap B L) y) = (algebraMap B L) x / (algebraMap B L) y
hy' : (algebraMap B L) y ≠ 0
a : A
ha : (algebraMap B L) ((algebraMap A B) a) ≠ 0
b : A
hb : x * (algebraMap A B) a = (algebraMap A B) b * y
hxy :
  (algebraMap B L) x / (algebraMap B L) y =
    (algebraMap B L) ((algebraMap A B) b) / (algebraMap B L) ((algebraMap A B) a)
⊢ (algebraMap B L) ((algebraMap A B) b) / (algebraMap K L) ((algebraMap A K) a) =
    (algebraMap B L) ((algebraMap A B) b) / (algebraMap B L) ((algebraMap A B) a)

Tactic:
hc

Goal state after:
case h
G : Type u_1
A : Type u_2
B : Type u_3
K : Type u_4
L : Type u_5
inst✝¹⁸ : Group G
inst✝¹⁷ : CommRing A
inst✝¹⁶ : CommRing B
inst✝¹⁵ : Algebra A B
inst✝¹⁴ : Field K
inst✝¹³ : Field L
inst✝¹² : Algebra K L
inst✝¹¹ : Algebra A K
inst✝¹⁰ : Algebra B L
inst✝⁹ : Algebra A L
inst✝⁸ : IsFractionRing A K
inst✝⁷ : IsFractionRing B L
inst✝⁶ : IsScalarTower A K L
inst✝⁵ : IsScalarTower A B L
inst✝⁴ : MulSemiringAction G B
inst✝³ : MulSemiringAction G L
inst✝² : SMulDistribClass G B L
hAB : Algebra.IsInvariant A B G
inst✝¹ : SMulCommClass G A B
inst✝ : Algebra.IsIntegral A B
hc : ∀ (a : A), (algebraMap K L) ((algebraMap A K) a) = (algebraMap B L) ((algebraMap A B) a)
this✝ : Nontrivial A
this : Nontrivial B
x y : B
hy : y ∈ nonZeroDivisors B
h : ∀ (g : G), g • ((algebraMap B L) x / (algebraMap B L) y) = (algebraMap B L) x / (algebraMap B L) y
hy' : (algebraMap B L) y ≠ 0
a : A
ha : (algebraMap B L) ((algebraMap A B) a) ≠ 0
b : A
hb : x * (algebraMap A B) a = (algebraMap A B) b * y
hxy :
  (algebraMap B L) x / (algebraMap B L) y =
    (algebraMap B L) ((algebraMap A B) b) / (algebraMap B L) ((algebraMap A B) a)
⊢ (algebraMap B L) ((algebraMap A B) b) / (algebraMap B L) ((algebraMap A B) a) =
    (algebraMap B L) ((algebraMap A B) b) / (algebraMap B L) ((algebraMap A B) a)
Module: Mathlib.RingTheory.Norm.Basic

Goal state before:
pp: case mp.refine_2
R : Type u_1
S : Type u_2
inst✝⁶ : CommRing R
inst✝⁵ : Ring S
inst✝⁴ : Algebra R S
inst✝³ : IsDomain R
inst✝² : IsDomain S
inst✝¹ : Free R S
inst✝ : Module.Finite R S
x : S
b : Basis (Free.ChooseBasisIndex R S) R S := Free.chooseBasis R S
decEq : DecidableEq (Free.ChooseBasisIndex R S) := Classical.decEq (Free.ChooseBasisIndex R S)
v : Free.ChooseBasisIndex R S → R
v_ne : v ≠ 0
hv : ⇑(b.repr (x * ∑ i, v i • b i)) = 0
⊢ ∑ i, v i • b i ≠ 0

Tactic:
· contrapose v_ne with sum_eq
      apply b.equivFun.symm.injective
      rw [b.equivFun_symm_apply, sum_eq, map_zero]

Goal state after:
Module: Mathlib.RingTheory.FiniteStability

Goal state before:
pp: R : Type w₁
inst✝⁴ : CommRing R
A : Type w₂
inst✝³ : CommRing A
inst✝² : Algebra R A
B : Type w₃
inst✝¹ : CommRing B
inst✝ : Algebra R B
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] A
hf : Function.Surjective ⇑f
g : B ⊗[R] MvPolynomial (Fin n) R →ₐ[B] B ⊗[R] A := TensorProduct.map (AlgHom.id B B) f
⊢ ∃ n f, Function.Surjective ⇑f

Tactic:
have : Function.Surjective g := baseChangeAux_surj B hf

Goal state after:
R : Type w₁
inst✝⁴ : CommRing R
A : Type w₂
inst✝³ : CommRing A
inst✝² : Algebra R A
B : Type w₃
inst✝¹ : CommRing B
inst✝ : Algebra R B
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] A
hf : Function.Surjective ⇑f
g : B ⊗[R] MvPolynomial (Fin n) R →ₐ[B] B ⊗[R] A := TensorProduct.map (AlgHom.id B B) f
this : Function.Surjective ⇑g
⊢ ∃ n f, Function.Surjective ⇑f
Module: Mathlib.RingTheory.Ideal.Norm.AbsNorm

Goal state before:
pp: S : Type u_1
inst✝¹ : CommRing S
P : Ideal S
P_prime : P.IsPrime
inst✝ : IsDedekindDomain S
hP : P ≠ ⊥
i : ℕ
ih : cardQuot (P ^ i) = cardQuot P ^ i
this : P ^ (i + 1) < P ^ i
hquot : ↥(map (mkQ (P ^ i.succ)) (P ^ i)) ≃ S ⧸ P
⊢ cardQuot (P ^ (i + 1)) = cardQuot P * cardQuot (P ^ i)

Tactic:
cardQuot_apply (P ^ i.succ),

Goal state after:
S : Type u_1
inst✝¹ : CommRing S
P : Ideal S
P_prime : P.IsPrime
inst✝ : IsDedekindDomain S
hP : P ≠ ⊥
i : ℕ
ih : cardQuot (P ^ i) = cardQuot P ^ i
this : P ^ (i + 1) < P ^ i
hquot : ↥(map (mkQ (P ^ i.succ)) (P ^ i)) ≃ S ⧸ P
⊢ Nat.card (S ⧸ P ^ i.succ) = cardQuot P * cardQuot (P ^ i)
Module: Mathlib.RingTheory.Ideal.Norm.AbsNorm

Goal state before:
pp: case succ.refine_2
S : Type u_1
inst✝¹ : CommRing S
P : Ideal S
P_prime : P.IsPrime
inst✝ : IsDedekindDomain S
hP : P ≠ ⊥
i : ℕ
ih : cardQuot (P ^ i) = cardQuot P ^ i
this : P ^ (i + 1) < P ^ i
a : S
a_mem : a ∈ P ^ i
a_notMem : a ∉ P ^ (i + 1)
f g : (c : S) → c ∈ P ^ i → S
hg : ∀ (c : S) (hc : c ∈ P ^ i), g c hc ∈ P ^ (i + 1)
hf : ∀ (c : S) (hc : c ∈ P ^ i), a * f c hc + g c hc = c
k : (c' : S ⧸ P ^ i.succ) → c' ∈ map (mkQ (P ^ i.succ)) (P ^ i) → S
hk_mem : ∀ (c' : S ⧸ P ^ i.succ) (hc' : c' ∈ map (mkQ (P ^ i.succ)) (P ^ i)), k c' hc' ∈ P ^ i
hk_eq : ∀ (c' : S ⧸ P ^ i.succ) (hc' : c' ∈ map (mkQ (P ^ i.succ)) (P ^ i)), (mkQ (P ^ i.succ)) (k c' hc') = c'
d' : S ⧸ P
⊢ ∃ a, (fun c' ↦ Quotient.mk'' (f (k ↑c' ⋯) ⋯)) a = d'

Tactic:
induction d' using Quotient.inductionOn with | _ d

Goal state after:
case succ.refine_2.h
S : Type u_1
inst✝¹ : CommRing S
P : Ideal S
P_prime : P.IsPrime
inst✝ : IsDedekindDomain S
hP : P ≠ ⊥
i : ℕ
ih : cardQuot (P ^ i) = cardQuot P ^ i
this : P ^ (i + 1) < P ^ i
a : S
a_mem : a ∈ P ^ i
a_notMem : a ∉ P ^ (i + 1)
f g : (c : S) → c ∈ P ^ i → S
hg : ∀ (c : S) (hc : c ∈ P ^ i), g c hc ∈ P ^ (i + 1)
hf : ∀ (c : S) (hc : c ∈ P ^ i), a * f c hc + g c hc = c
k : (c' : S ⧸ P ^ i.succ) → c' ∈ map (mkQ (P ^ i.succ)) (P ^ i) → S
hk_mem : ∀ (c' : S ⧸ P ^ i.succ) (hc' : c' ∈ map (mkQ (P ^ i.succ)) (P ^ i)), k c' hc' ∈ P ^ i
hk_eq : ∀ (c' : S ⧸ P ^ i.succ) (hc' : c' ∈ map (mkQ (P ^ i.succ)) (P ^ i)), (mkQ (P ^ i.succ)) (k c' hc') = c'
d : S
⊢ ∃ a, (fun c' ↦ Quotient.mk'' (f (k ↑c' ⋯) ⋯)) a = ⟦d⟧
Module: Mathlib.RingTheory.Ideal.Norm.AbsNorm

Goal state before:
pp: S : Type u_1
inst✝³ : CommRing S
inst✝² : IsDedekindDomain S
inst✝¹ : Free ℤ S
inst✝ : Module.Finite ℤ S
I : Ideal S
⊢ ¬absNorm I = 0 ↔ I ∈ (Ideal S)⁰

Tactic:
Ideal.absNorm_eq_zero_iff,

Goal state after:
S : Type u_1
inst✝³ : CommRing S
inst✝² : IsDedekindDomain S
inst✝¹ : Free ℤ S
inst✝ : Module.Finite ℤ S
I : Ideal S
⊢ ¬I = ⊥ ↔ I ∈ (Ideal S)⁰
Module: Mathlib.RingTheory.Localization.InvSubmonoid

Goal state before:
pp: R : Type u_1
inst✝³ : CommRing R
M : Submonoid R
S : Type u_2
inst✝² : CommRing S
inst✝¹ : Algebra R S
inst✝ : IsLocalization M S
m : ↥M
⊢ m • ↑((toInvSubmonoid M S) m) = 1

Tactic:
convert! mul_toInvSubmonoid M S m
  ext
  rw [← Algebra.smul_def]
  rfl

Goal state after:
Module: Mathlib.RingTheory.HopkinsLevitzki

Goal state before:
pp: case zero
R₀ : Type u_1
R : Type u_2
inst✝⁷ : Ring R₀
inst✝⁶ : Ring R
inst✝⁵ : Module R₀ R
inst✝⁴ : IsSemiprimaryRing R
P : (M : Type u) → [inst : AddCommGroup M] → [Module R₀ M] → [Module R M] → Prop
ss : IsSemisimpleRing (R ⧸ Ring.jacobson R)
Jac : Ideal R := Ring.jacobson R
h0 :
  ∀ (M : Type u) [inst : AddCommGroup M] [inst_1 : Module R₀ M] [inst_2 : Module R M] [IsScalarTower R₀ R M]
    [IsSemisimpleModule R M], Module.IsTorsionBySet R M ↑Jac → P M
h1 :
  ∀ (M : Type u) [inst : AddCommGroup M] [inst_1 : Module R₀ M] [inst_2 : Module R M] [inst_3 : IsScalarTower R₀ R M],
    let N := Jac • ⊤;
    P ↥N → P (M ⧸ N) → P M
this :
  ∀ {M : Type u} [inst : AddCommGroup M] [inst_1 : Module R₀ M] [inst_2 : Module R M] [IsScalarTower R₀ R M],
    Jac ≤ Module.annihilator R M → P M
M : Type u
inst✝³ : AddCommGroup M
inst✝² : Module R₀ M
inst✝¹ : Module R M
inst✝ : IsScalarTower R₀ R M
hn : Jac ^ 0 ≤ Module.annihilator R M
⊢ P M

Tactic:
rw [Jac.pow_zero, Ideal.one_eq_top] at hn

Goal state after:
case zero
R₀ : Type u_1
R : Type u_2
inst✝⁷ : Ring R₀
inst✝⁶ : Ring R
inst✝⁵ : Module R₀ R
inst✝⁴ : IsSemiprimaryRing R
P : (M : Type u) → [inst : AddCommGroup M] → [Module R₀ M] → [Module R M] → Prop
ss : IsSemisimpleRing (R ⧸ Ring.jacobson R)
Jac : Ideal R := Ring.jacobson R
h0 :
  ∀ (M : Type u) [inst : AddCommGroup M] [inst_1 : Module R₀ M] [inst_2 : Module R M] [IsScalarTower R₀ R M]
    [IsSemisimpleModule R M], Module.IsTorsionBySet R M ↑Jac → P M
h1 :
  ∀ (M : Type u) [inst : AddCommGroup M] [inst_1 : Module R₀ M] [inst_2 : Module R M] [inst_3 : IsScalarTower R₀ R M],
    let N := Jac • ⊤;
    P ↥N → P (M ⧸ N) → P M
this :
  ∀ {M : Type u} [inst : AddCommGroup M] [inst_1 : Module R₀ M] [inst_2 : Module R M] [IsScalarTower R₀ R M],
    Jac ≤ Module.annihilator R M → P M
M : Type u
inst✝³ : AddCommGroup M
inst✝² : Module R₀ M
inst✝¹ : Module R M
inst✝ : IsScalarTower R₀ R M
hn : ⊤ ≤ Module.annihilator R M
⊢ P M
Module: Mathlib.RingTheory.HopkinsLevitzki

Goal state before:
pp: R₀ : Type u_1
R : Type u_2
M✝ : Type u
inst✝⁹ : Ring R₀
inst✝⁸ : Ring R
inst✝⁷ : Module R₀ R
inst✝⁶ : AddCommGroup M✝
inst✝⁵ : Module R₀ M✝
inst✝⁴ : Module R M✝
inst✝³ : IsScalarTower R₀ R M✝
inst✝² : IsSemiprimaryRing R
inst✝¹ : IsScalarTower R₀ R R
inst✝ : Module.Finite R₀ (R ⧸ Ring.jacobson R)
M : Type u
x✝³ : AddCommGroup M
x✝² : Module R₀ M
x✝¹ : Module R M
x✝ : IsScalarTower R₀ R M
hs :
  IsNoetherian R ↥(Ring.jacobson R • ⊤) ∨ IsArtinian R ↥(Ring.jacobson R • ⊤) → Module.Finite R₀ ↥(Ring.jacobson R • ⊤)
hq :
  IsNoetherian R (M ⧸ Ring.jacobson R • ⊤) ∨ IsArtinian R (M ⧸ Ring.jacobson R • ⊤) →
    Module.Finite R₀ (M ⧸ Ring.jacobson R • ⊤)
h : IsNoetherian R M ∨ IsArtinian R M
N : Submodule R₀ M := Submodule.restrictScalars R₀ (Ring.jacobson R • ⊤)
⊢ Module.Finite R₀ ↥N

Tactic:
refine hs (h.imp ?_ ?_) <;> (intro; infer_instance)

Goal state after:
Module: Mathlib.RingTheory.HopkinsLevitzki

Goal state before:
pp: R : Type u_2
M✝ : Type u
inst✝³ : Ring R
inst✝² : AddCommGroup M✝
inst✝¹ : Module R M✝
inst✝ : IsSemiprimaryRing R
M : Type u
x✝³ : AddCommGroup M
x✝² x✝¹ : Module R M
x✝ : IsScalarTower R R M
h : IsNoetherian R ↥(Ring.jacobson R • ⊤) ↔ IsArtinian R ↥(Ring.jacobson R • ⊤)
h' : IsNoetherian R (M ⧸ Ring.jacobson R • ⊤) ↔ IsArtinian R (M ⧸ Ring.jacobson R • ⊤)
N : Submodule R M := Ring.jacobson R • ⊤
⊢ IsNoetherian R M ↔ IsArtinian R M

Tactic:
isNoetherian_iff_submodule_quotient N,

Goal state after:
R : Type u_2
M✝ : Type u
inst✝³ : Ring R
inst✝² : AddCommGroup M✝
inst✝¹ : Module R M✝
inst✝ : IsSemiprimaryRing R
M : Type u
x✝³ : AddCommGroup M
x✝² x✝¹ : Module R M
x✝ : IsScalarTower R R M
h : IsNoetherian R ↥(Ring.jacobson R • ⊤) ↔ IsArtinian R ↥(Ring.jacobson R • ⊤)
h' : IsNoetherian R (M ⧸ Ring.jacobson R • ⊤) ↔ IsArtinian R (M ⧸ Ring.jacobson R • ⊤)
N : Submodule R M := Ring.jacobson R • ⊤
⊢ IsNoetherian R ↥N ∧ IsNoetherian R (M ⧸ N) ↔ IsArtinian R M
Module: Mathlib.RingTheory.Ideal.IdempotentFG

Goal state before:
pp: R : Type u_1
inst✝ : CommRing R
I : Ideal R
h : I.FG
e : IsIdempotentElem I
⊢ I ≤ I • I

Tactic:
smul_eq_mul

Goal state after:
R : Type u_1
inst✝ : CommRing R
I : Ideal R
h : I.FG
e : IsIdempotentElem I
⊢ I ≤ I * I
Module: Mathlib.RingTheory.Ideal.IdempotentFG

Goal state before:
pp: case mp
R : Type u_1
inst✝ : CommRing R
I : Ideal R
h : I.FG
e : IsIdempotentElem I
r : R
hr : r ∈ I
hr' : ∀ n ∈ I, r • n = n
⊢ ∃ e, IsIdempotentElem e ∧ I = R ∙ e

Tactic:
smul_eq_mul

Goal state after:
case mp
R : Type u_1
inst✝ : CommRing R
I : Ideal R
h : I.FG
e : IsIdempotentElem I
r : R
hr : r ∈ I
hr' : ∀ n ∈ I, r * n = n
⊢ ∃ e, IsIdempotentElem e ∧ I = R ∙ e