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

Goal state before:
pp: 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✝¹ : 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
g : G
hg : g • Q ≠ Q
hr : r = ∑ i ∈ Finset.range (k + 1), (monomial i) (f.coeff (i + j))
⊢ eval b ((∑ i ∈ Finset.range k, (monomial i) (f.coeff (i + 1 + j))) * X) ∈ g • Q

Tactic:
Polynomial.eval_mul_X

Goal state after:
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✝¹ : 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
g : G
hg : g • Q ≠ Q
hr : r = ∑ i ∈ Finset.range (k + 1), (monomial i) (f.coeff (i + j))
⊢ eval b (∑ i ∈ Finset.range k, (monomial i) (f.coeff (i + 1 + j))) * b ∈ g • Q
Module: Mathlib.RingTheory.Trace.Basic

Goal state before:
pp: κ : Type w
A : Type u
B : Type v
inst✝³ : CommRing A
inst✝² : CommRing B
inst✝¹ : Algebra A B
inst✝ : Fintype κ
b : κ → B
P : Matrix κ κ A
α β : κ
⊢ ((traceForm A B) (∑ i, b i * P.map (⇑(algebraMap A B)) i α)) (∑ i, b i * P.map (⇑(algebraMap A B)) i β) =
    ∑ j, (Pᵀ * traceMatrix A b) α j * P j β

Tactic:
BilinForm.sum_left,

Goal state after:
κ : Type w
A : Type u
B : Type v
inst✝³ : CommRing A
inst✝² : CommRing B
inst✝¹ : Algebra A B
inst✝ : Fintype κ
b : κ → B
P : Matrix κ κ A
α β : κ
⊢ ∑ i, ((traceForm A B) (b i * P.map (⇑(algebraMap A B)) i α)) (∑ i, b i * P.map (⇑(algebraMap A B)) i β) =
    ∑ j, (Pᵀ * traceMatrix A b) α j * P j β
Module: Mathlib.RingTheory.Trace.Basic

Goal state before:
pp: κ : Type w
A : Type u
B : Type v
inst✝³ : CommRing A
inst✝² : CommRing B
inst✝¹ : Algebra A B
inst✝ : Fintype κ
b : κ → B
P : Matrix κ κ A
⊢ (transposeAddEquiv κ κ A) (traceMatrix A (P.map ⇑(algebraMap A B) *ᵥ b)) =
    (transposeAddEquiv κ κ A) (P * traceMatrix A b * Pᵀ)

Tactic:
transposeAddEquiv_apply,

Goal state after:
κ : Type w
A : Type u
B : Type v
inst✝³ : CommRing A
inst✝² : CommRing B
inst✝¹ : Algebra A B
inst✝ : Fintype κ
b : κ → B
P : Matrix κ κ A
⊢ (traceMatrix A (P.map ⇑(algebraMap A B) *ᵥ b))ᵀ = (transposeAddEquiv κ κ A) (P * traceMatrix A b * Pᵀ)
Module: Mathlib.RingTheory.Trace.Basic

Goal state before:
pp: κ : Type w
A : Type u
B : Type v
inst✝³ : CommRing A
inst✝² : CommRing B
inst✝¹ : Algebra A B
inst✝ : Fintype κ
b : κ → B
P : Matrix κ κ A
⊢ (traceMatrix A (P.map ⇑(algebraMap A B) *ᵥ b))ᵀ = (transposeAddEquiv κ κ A) (P * traceMatrix A b * Pᵀ)

Tactic:
transposeAddEquiv_apply,

Goal state after:
κ : Type w
A : Type u
B : Type v
inst✝³ : CommRing A
inst✝² : CommRing B
inst✝¹ : Algebra A B
inst✝ : Fintype κ
b : κ → B
P : Matrix κ κ A
⊢ (traceMatrix A (P.map ⇑(algebraMap A B) *ᵥ b))ᵀ = (P * traceMatrix A b * Pᵀ)ᵀ
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
⊢ Finite G

Tactic:
let A : Subring B := (algebraMap R B).range
  let := FractionRing.liftAlgebra A (FractionRing B)
  let := IsFractionRing.mulSemiringAction G B (FractionRing B)
  let : Algebra R A := (algebraMap R B).rangeRestrict.toAlgebra
  have : IsScalarTower R A B := IsScalarTower.of_algebraMap_eq' rfl
  have : Module.Finite A B := Module.Finite.of_restrictScalars_finite R A B
  have := IsGaloisGroup.to_isFractionRing_of_isIntegral G A B (FractionRing A) (FractionRing B)
  apply Nat.finite_of_card_ne_zero
  rw [card_eq_finrank G (FractionRing A) (FractionRing B)]
  exact Module.finrank_pos.ne'

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

Goal state before:
pp: K : Type u_1
inst✝² : CommRing K
inst✝¹ : NoZeroDivisors K
G : Subgroup Kˣ
inst✝ : Fintype ↥G
k : ℕ
k_pos : k ≠ 0
k_lt_card_G : k < Nat.card ↥G
a✝ : Nontrivial K
this : IsDomain K
a : ↥G
ha : a ^ k ≠ 1
h_multiset_map : Multiset.map (fun x ↦ ↑↑x ^ k) univ.val = Multiset.map (fun x ↦ ↑↑x ^ k * ↑↑a ^ k) univ.val
h_multiset_map_sum :
  (Multiset.map (fun x ↦ ↑↑x ^ k) univ.val).sum = (Multiset.map (fun x ↦ ↑↑x ^ k) univ.val).sum * ↑↑a ^ k
hzero : ↑↑a ^ k - 1 = 0 ∨ (Multiset.map (fun i ↦ ↑↑i ^ k) univ.val).sum = 0
h : ↑↑a ^ k - 1 = 0
⊢ ↑↑(a ^ k) = ↑↑1

Tactic:
rw [← sub_eq_zero]

Goal state after:
K : Type u_1
inst✝² : CommRing K
inst✝¹ : NoZeroDivisors K
G : Subgroup Kˣ
inst✝ : Fintype ↥G
k : ℕ
k_pos : k ≠ 0
k_lt_card_G : k < Nat.card ↥G
a✝ : Nontrivial K
this : IsDomain K
a : ↥G
ha : a ^ k ≠ 1
h_multiset_map : Multiset.map (fun x ↦ ↑↑x ^ k) univ.val = Multiset.map (fun x ↦ ↑↑x ^ k * ↑↑a ^ k) univ.val
h_multiset_map_sum :
  (Multiset.map (fun x ↦ ↑↑x ^ k) univ.val).sum = (Multiset.map (fun x ↦ ↑↑x ^ k) univ.val).sum * ↑↑a ^ k
hzero : ↑↑a ^ k - 1 = 0 ∨ (Multiset.map (fun i ↦ ↑↑i ^ k) univ.val).sum = 0
h : ↑↑a ^ k - 1 = 0
⊢ ↑↑(a ^ k) - ↑↑1 = 0
Module: Mathlib.LinearAlgebra.FreeModule.Determinant

Goal state before:
pp: R : Type u_1
M : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
inst✝² : Module.Free R M
inst✝¹ : Module.Finite R M
inst✝ : Nontrivial M
this : Nonempty (Module.Free.ChooseBasisIndex R M) := Module.Basis.index_nonempty (Module.Free.chooseBasis R M)
⊢ LinearMap.det 0 = 0

Tactic:
nontriviality R

Goal state after:
R : Type u_1
M : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
inst✝² : Module.Free R M
inst✝¹ : Module.Finite R M
inst✝ : Nontrivial M
this : Nonempty (Module.Free.ChooseBasisIndex R M) := Module.Basis.index_nonempty (Module.Free.chooseBasis R M)
a✝ : Nontrivial R
⊢ LinearMap.det 0 = 0
Module: Mathlib.FieldTheory.Finite.Basic

Goal state before:
pp: K : Type u_1
R : Type u_2
inst✝³ : Field K
inst✝² : Fintype K
inst✝¹ : CommRing R
inst✝ : Algebra K R
x✝¹ x✝ : R
p : ℕ
left✝ : CharP K p
w✝ : ℕ+
hp : Nat.Prime p
card_eq : failed to pretty print expression (use 'set_option pp.rawOnError true' for raw representation)
⊢ failed to pretty print expression (use 'set_option pp.rawOnError true' for raw representation)

Tactic:
nontriviality R

Goal state after:
K : Type u_1
R : Type u_2
inst✝³ : Field K
inst✝² : Fintype K
inst✝¹ : CommRing R
inst✝ : Algebra K R
x✝¹ x✝ : R
p : ℕ
left✝ : CharP K p
w✝ : ℕ+
hp : Nat.Prime p
card_eq : failed to pretty print expression (use 'set_option pp.rawOnError true' for raw representation)
a✝ : Nontrivial R
⊢ failed to pretty print expression (use 'set_option pp.rawOnError true' for raw representation)
Module: Mathlib.RingTheory.Int.Basic

Goal state before:
pp: a b c : ℤ
hab : IsCoprime a b
k : ℕ
hk : Odd k
h : a * b = c ^ k
d : ℤ
hd : Associated a (d ^ k)
⊢ ∃ d, a = d ^ k

Tactic:
associated_iff_natAbs,

Goal state after:
a b c : ℤ
hab : IsCoprime a b
k : ℕ
hk : Odd k
h : a * b = c ^ k
d : ℤ
hd : a.natAbs = (d ^ k).natAbs
⊢ ∃ d, a = d ^ k
Module: Mathlib.FieldTheory.Finite.Basic

Goal state before:
pp: K : Type u_1
R : Type u_2
inst✝⁵ : Field K
inst✝⁴ : Fintype K
inst✝³ : CommRing R
inst✝² : Algebra K R
p : ℕ
inst✝¹ : ExpChar R p
inst✝ : PerfectRing R p
p' : ℕ
left✝ : CharP K p'
n : ℕ+
hp : Nat.Prime p'
card_eq : failed to pretty print expression (use 'set_option pp.rawOnError true' for raw representation)
this : ExpChar K p'
⊢ Function.Bijective fun x ↦ x ^ p' ^ ↑n

Tactic:
nontriviality R

Goal state after:
K : Type u_1
R : Type u_2
inst✝⁵ : Field K
inst✝⁴ : Fintype K
inst✝³ : CommRing R
inst✝² : Algebra K R
p : ℕ
inst✝¹ : ExpChar R p
inst✝ : PerfectRing R p
p' : ℕ
left✝ : CharP K p'
n : ℕ+
hp : Nat.Prime p'
card_eq : failed to pretty print expression (use 'set_option pp.rawOnError true' for raw representation)
this : ExpChar K p'
a✝ : Nontrivial R
⊢ Function.Bijective fun x ↦ x ^ p' ^ ↑n
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
a b : B
ha1 : ∀ (g : G), g • a = a
ha2 : a ∉ Q
hb : ∀ (g : G), (algebraMap B (B ⧸ Q)) (g • b) = (algebraMap B (B ⧸ Q)) (if g • Q = Q then a * b₀ else 0)
M : A[X]
key₀ :
  ∀ (g : G),
    map (algebraMap B (B ⧸ Q)) (X - C (g • b)) = if g • Q = Q then X - C ((algebraMap B (B ⧸ Q)) (a * b₀)) else X
key :
  map (algebraMap K L) (map (algebraMap (A ⧸ P) K) (map (algebraMap A (A ⧸ P)) M)) =
    (X - map (algebraMap (B ⧸ Q) L) (C ((algebraMap B (B ⧸ Q)) (a * b₀)))) ^ {x | x • Q = Q}.card *
      X ^ {x | ¬x • Q = Q}.card
⊢ f ((algebraMap (B ⧸ Q) L) ((algebraMap B (B ⧸ Q)) b₀)) = (algebraMap (B ⧸ Q) L) ((algebraMap B (B ⧸ Q)) b₀)

Tactic:
map_C

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
a b : B
ha1 : ∀ (g : G), g • a = a
ha2 : a ∉ Q
hb : ∀ (g : G), (algebraMap B (B ⧸ Q)) (g • b) = (algebraMap B (B ⧸ Q)) (if g • Q = Q then a * b₀ else 0)
M : A[X]
key₀ :
  ∀ (g : G),
    map (algebraMap B (B ⧸ Q)) (X - C (g • b)) = if g • Q = Q then X - C ((algebraMap B (B ⧸ Q)) (a * b₀)) else X
key :
  map (algebraMap K L) (map (algebraMap (A ⧸ P) K) (map (algebraMap A (A ⧸ P)) M)) =
    (X - C ((algebraMap (B ⧸ Q) L) ((algebraMap B (B ⧸ Q)) (a * b₀)))) ^ {x | x • Q = Q}.card *
      X ^ {x | ¬x • Q = Q}.card
⊢ f ((algebraMap (B ⧸ Q) L) ((algebraMap B (B ⧸ Q)) b₀)) = (algebraMap (B ⧸ Q) L) ((algebraMap B (B ⧸ Q)) b₀)
Module: Mathlib.FieldTheory.Finite.Basic

Goal state before:
pp: K : Type u_1
inst✝¹ : Field K
inst✝ : Fintype K
aux : X ^ q - X ≠ 0
⊢ (X ^ q - X).roots.toFinset = univ

Tactic:
eq_univ_iff_forall

Goal state after:
K : Type u_1
inst✝¹ : Field K
inst✝ : Fintype K
aux : X ^ q - X ≠ 0
⊢ ∀ (x : K), x ∈ (X ^ q - X).roots.toFinset
Module: Mathlib.FieldTheory.Galois.IsGaloisGroup

Goal state before:
pp: G : Type u_1
K : Type u_3
L : Type u_4
inst✝⁸ : Group G
inst✝⁷ : Field K
inst✝⁶ : Field L
inst✝⁵ : Algebra K L
inst✝⁴ : MulSemiringAction G L
H : Subgroup G
F : IntermediateField K L
N : Subgroup G
inst✝³ : N.Normal
inst✝² : IsGaloisGroup (↥N) (↥F) L
E : IntermediateField K L
hE : IsGaloisGroup (↥H) (↥E) L
inst✝¹ : Finite G
inst✝ : IsGaloisGroup G K L
h✝ : E ≤ F
this✝³ : Algebra ↥E ↥F := (IntermediateField.inclusion h✝).toAlgebra
this✝² : SMul G ↥F := smulOfNormal G (↥F) L N
this✝¹ : SMulDistribClass G (↥F) L
this✝ : MulSemiringAction G ↥F := mulSemiringActionOfSmulDistribClass (↥F) L G
this : IsScalarTower (↥E) (↥F) L
x : ↥F
h : ∀ (g : ↥(Subgroup.map (QuotientGroup.mk' N) H)), g • x = x
⊢ ∃ a, (algebraMap ↥E ↥F) a = x

Tactic:
obtain ⟨a, ha⟩ := hE.isInvariant.isInvariant (algebraMap F L x) (by
        rintro ⟨g, hg⟩
        rw [MulAction.subgroup_smul_def, ← algebraMap.smul']
        exact congr_arg (algebraMap F L) <| h ⟨g, ⟨g, hg, rfl⟩⟩)
      exact ⟨a, FaithfulSMul.algebraMap_injective F L
        (by rw [← IsScalarTower.algebraMap_apply, ha])⟩

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

Goal state before:
pp: case inr
p : ℕ
hp : Fact (Nat.Prime p)
x : ZMod p
hp_odd : p % 2 = 1
f : (ZMod p)[X] := X ^ 2
g : (ZMod p)[X] := X ^ 2 - C x
a b : ZMod p
hab : eval a f + eval b g = 0
⊢ a ^ 2 + b ^ 2 = x

Tactic:
rw [← sub_eq_zero]

Goal state after:
case inr
p : ℕ
hp : Fact (Nat.Prime p)
x : ZMod p
hp_odd : p % 2 = 1
f : (ZMod p)[X] := X ^ 2
g : (ZMod p)[X] := X ^ 2 - C x
a b : ZMod p
hab : eval a f + eval b g = 0
⊢ a ^ 2 + b ^ 2 - x = 0
Module: Mathlib.FieldTheory.Finite.Basic

Goal state before:
pp: R : Type u_3
inst✝³ : Ring R
inst✝² : IsDomain R
p : ℕ
inst✝¹ : NeZero p
inst✝ : CharP R p
x : ℤ
this : Fact (Nat.Prime p)
⊢ ∃ a b, ↑a ^ 2 + ↑b ^ 2 = ↑x

Tactic:
obtain ⟨a, b, hab⟩ := ZMod.sq_add_sq p x

Goal state after:
R : Type u_3
inst✝³ : Ring R
inst✝² : IsDomain R
p : ℕ
inst✝¹ : NeZero p
inst✝ : CharP R p
x : ℤ
this : Fact (Nat.Prime p)
a b : ZMod p
hab : a ^ 2 + b ^ 2 = ↑x
⊢ ∃ a b, ↑a ^ 2 + ↑b ^ 2 = ↑x
Module: Mathlib.FieldTheory.Finite.Basic

Goal state before:
pp: K : Type u_1
p : ℕ
inst✝² : Fact (Nat.Prime p)
inst✝¹ : DivisionRing K
inst✝ : CharP K p
⊢ Subfield.map (castHom ⋯ K) ⊤ = ⊥

Tactic:
← Subfield.map_bot (K := ZMod p),

Goal state after:
K : Type u_1
p : ℕ
inst✝² : Fact (Nat.Prime p)
inst✝¹ : DivisionRing K
inst✝ : CharP K p
⊢ Subfield.map (castHom ⋯ K) ⊤ = Subfield.map ?m.26 ⊥

K : Type u_1
p : ℕ
inst✝² : Fact (Nat.Prime p)
inst✝¹ : DivisionRing K
inst✝ : CharP K p
⊢ ZMod p →+* K
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 : g ^ (n * (Nat.card F / 2)) = 1
⊢ Nat.card Fˣ ∣ n * (Nat.card F / 2)

Tactic:
← orderOf_eq_card_of_forall_mem_zpowers hg

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
⊢ orderOf g ∣ n * (Nat.card F / 2)
Module: Mathlib.LinearAlgebra.FreeModule.Finite.CardQuotient

Goal state before:
pp: case neg
M : Type u_1
inst✝⁴ : AddCommGroup M
inst✝³ : Free ℤ M
inst✝² : Module.Finite ℤ M
N : Submodule ℤ M
E : Type u_2
inst✝¹ : EquivLike E M ↥N
inst✝ : AddEquivClass E M ↥N
e : E
b : Basis (Free.ChooseBasisIndex ℤ M) ℤ M := Free.chooseBasis ℤ M
h✝ : finrank ℤ ↥N = finrank ℤ M
a : Free.ChooseBasisIndex ℤ M → ℤ := smithNormalFormCoeffs b h✝
b' : Basis (Free.ChooseBasisIndex ℤ M) ℤ M := smithNormalFormTopBasis b h✝
ab : Basis (Free.ChooseBasisIndex ℤ M) ℤ ↥N := smithNormalFormBotBasis b h✝
ab_eq :
  ∀ (i : Free.ChooseBasisIndex ℤ M),
    ↑((smithNormalFormBotBasis b h✝) i) = smithNormalFormCoeffs b h✝ i • (smithNormalFormTopBasis b h✝) i
e' : M ≃ₗ[ℤ] ↥N := b'.equiv ab (Equiv.refl (Free.ChooseBasisIndex ℤ M))
f : M →ₗ[ℤ] M := N.subtype ∘ₗ ↑e'
f_apply : ∀ (x : M), f x = ↑((b'.equiv ab (Equiv.refl (Free.ChooseBasisIndex ℤ M))) x) := fun x ↦ rfl
ha : ∀ (i : Free.ChooseBasisIndex ℤ M), f (b' i) = a i • b' i
i j : Free.ChooseBasisIndex ℤ M
h : ¬i = j
⊢ (Finsupp.single j (a j)) i = 0

Tactic:
Finsupp.single_eq_of_ne h

Goal state after:
case neg
M : Type u_1
inst✝⁴ : AddCommGroup M
inst✝³ : Free ℤ M
inst✝² : Module.Finite ℤ M
N : Submodule ℤ M
E : Type u_2
inst✝¹ : EquivLike E M ↥N
inst✝ : AddEquivClass E M ↥N
e : E
b : Basis (Free.ChooseBasisIndex ℤ M) ℤ M := Free.chooseBasis ℤ M
h✝ : finrank ℤ ↥N = finrank ℤ M
a : Free.ChooseBasisIndex ℤ M → ℤ := smithNormalFormCoeffs b h✝
b' : Basis (Free.ChooseBasisIndex ℤ M) ℤ M := smithNormalFormTopBasis b h✝
ab : Basis (Free.ChooseBasisIndex ℤ M) ℤ ↥N := smithNormalFormBotBasis b h✝
ab_eq :
  ∀ (i : Free.ChooseBasisIndex ℤ M),
    ↑((smithNormalFormBotBasis b h✝) i) = smithNormalFormCoeffs b h✝ i • (smithNormalFormTopBasis b h✝) i
e' : M ≃ₗ[ℤ] ↥N := b'.equiv ab (Equiv.refl (Free.ChooseBasisIndex ℤ M))
f : M →ₗ[ℤ] M := N.subtype ∘ₗ ↑e'
f_apply : ∀ (x : M), f x = ↑((b'.equiv ab (Equiv.refl (Free.ChooseBasisIndex ℤ M))) x) := fun x ↦ rfl
ha : ∀ (i : Free.ChooseBasisIndex ℤ M), f (b' i) = a i • b' i
i j : Free.ChooseBasisIndex ℤ M
h : ¬i = j
⊢ 0 = 0
Module: Mathlib.RingTheory.Norm.Basic

Goal state before:
pp: R : Type u_1
S : Type u_2
T : Type u_3
inst✝⁴ : CommRing R
inst✝³ : Ring S
inst✝² : Algebra R S
inst✝¹ : Ring T
inst✝ : Algebra R T
e : S ≃ₐ[R] T
x : S
⊢ (norm R) (e x) = (norm R) x

Tactic:
Algebra.norm_apply,

Goal state after:
R : Type u_1
S : Type u_2
T : Type u_3
inst✝⁴ : CommRing R
inst✝³ : Ring S
inst✝² : Algebra R S
inst✝¹ : Ring T
inst✝ : Algebra R T
e : S ≃ₐ[R] T
x : S
⊢ LinearMap.det ((lmul R T) (e x)) = LinearMap.det ((lmul R S) x)
Module: Mathlib.RingTheory.Norm.Basic

Goal state before:
pp: case refine_2
A₁ : Type u_8
B₁ : Type u_9
A₂ : Type u_10
B₂ : Type u_11
inst✝⁵ : CommRing A₁
inst✝⁴ : Ring B₁
inst✝³ : CommRing A₂
inst✝² : Ring B₂
inst✝¹ : Algebra A₁ B₁
inst✝ : Algebra A₂ B₂
e₁ : A₁ ≃+* A₂
e₂ : B₁ ≃+* B₂
he : (algebraMap A₂ B₂).comp ↑e₁ = (↑e₂).comp (algebraMap A₁ B₁)
x : B₁
this : Algebra A₁ B₂ := ((↑e₂).comp (algebraMap A₁ B₁)).toAlgebra' ?refine_1
e' : B₁ ≃ₐ[A₁] B₂ := { toEquiv := e₂.toEquiv, map_mul' := ⋯, map_add' := ⋯, commutes' := ⋯ }
⊢ (norm A₁) x = e₁.symm (e₁ ((norm A₁) (e₂ x)))

Tactic:
← Algebra.norm_eq_of_algEquiv e'

Goal state after:
case refine_2
A₁ : Type u_8
B₁ : Type u_9
A₂ : Type u_10
B₂ : Type u_11
inst✝⁵ : CommRing A₁
inst✝⁴ : Ring B₁
inst✝³ : CommRing A₂
inst✝² : Ring B₂
inst✝¹ : Algebra A₁ B₁
inst✝ : Algebra A₂ B₂
e₁ : A₁ ≃+* A₂
e₂ : B₁ ≃+* B₂
he : (algebraMap A₂ B₂).comp ↑e₁ = (↑e₂).comp (algebraMap A₁ B₁)
x : B₁
this : Algebra A₁ B₂ := ((↑e₂).comp (algebraMap A₁ B₁)).toAlgebra' ?refine_1
e' : B₁ ≃ₐ[A₁] B₂ := { toEquiv := e₂.toEquiv, map_mul' := ⋯, map_add' := ⋯, commutes' := ⋯ }
⊢ (norm A₁) (e' x) = e₁.symm (e₁ ((norm A₁) (e₂ x)))
Module: Mathlib.GroupTheory.Submonoid.Inverses

Goal state before:
pp: M : Type u_1
inst✝ : CommMonoid M
S : Submonoid M
hS : S ≤ IsUnit.submonoid M
x : ↥S.leftInv
⊢ ↑x * ↑((S.leftInvEquiv hS) x) = 1

Tactic:
by
  simp only [leftInvEquiv_apply, fromCommLeftInv, mul_fromLeftInv]

Goal state after:
Module: Mathlib.RingTheory.LocalRing.Length

Goal state before:
pp: case neg
A : Type u_1
B : Type u_2
M : Type u_3
inst✝⁸ : CommRing A
inst✝⁷ : CommRing B
inst✝⁶ : IsLocalRing A
inst✝⁵ : IsLocalRing B
inst✝⁴ : Algebra A B
inst✝³ : IsLocalHom (algebraMap A B)
inst✝² : AddCommGroup M
inst✝¹ : Module A M
inst✝ : Flat A B
h : ¬IsFiniteLength A M
⊢ length B (B ⊗[A] M) = length A M * length B (B ⧸ Ideal.map (algebraMap A B) (maximalIdeal A))

Tactic:
· have : ¬ IsFiniteLength B (B ⊗[A] M) := by
      contrapose! h
      rw [isFiniteLength_iff_isNoetherian_isArtinian] at h ⊢
      have : FaithfullyFlat A B := FaithfullyFlat.of_flat_of_isLocalHom
      exact h.imp IsNoetherian.of_isNoetherian_tensorProduct_of_faithfullyFlat
        IsArtinian.of_isArtinian_tensorProduct_of_faithfullyFlat
    rw [← length_ne_top_iff, not_ne_iff] at h this
    have ne : length B (B ⧸ (maximalIdeal A).map (algebraMap A B)) ≠ 0 := by
      simpa [← pos_iff_ne_zero, length_pos_iff] using (map_maximalIdeal_lt_top (algebraMap A B)).ne
    rw [h, this, ENat.top_mul ne]

Goal state after:
Module: Mathlib.RingTheory.Unramified.Finite

Goal state before:
pp: R : Type u_1
S : Type u_2
inst✝³ : CommRing R
inst✝² : CommRing S
inst✝¹ : Algebra R S
inst✝ : EssFiniteType R S
⊢ FormallyUnramified R S ↔ ∃ t, (∀ (s : S), (1 ⊗ₜ[R] s - s ⊗ₜ[R] 1) * t = 0) ∧ (TensorProduct.lmul' R) t = 1

Tactic:
rw [formallyUnramified_iff, KaehlerDifferential,
    Ideal.cotangent_subsingleton_iff, Ideal.isIdempotentElem_iff_of_fg _
      (KaehlerDifferential.ideal_fg R S)]
  have : ∀ t : S ⊗[R] S, TensorProduct.lmul' R t = 1 ↔ 1 - t ∈ KaehlerDifferential.ideal R S := by
    intro t
    simp only [KaehlerDifferential.ideal, RingHom.mem_ker, map_sub, map_one,
      sub_eq_zero, @eq_comm S 1]
  simp_rw [this, ← KaehlerDifferential.span_range_eq_ideal]
  constructor
  · rintro ⟨e, he₁, he₂ : _ = Ideal.span _⟩
    refine ⟨1 - e, ?_, ?_⟩
    · intro s
      obtain ⟨x, hx⟩ : e ∣ 1 ⊗ₜ[R] s - s ⊗ₜ[R] 1 := by
        rw [← Ideal.mem_span_singleton, ← he₂]
        exact Ideal.subset_span ⟨s, rfl⟩
      rw [hx, mul_comm, ← mul_assoc, sub_mul, one_mul, he₁.eq, sub_self, zero_mul]
    · rw [sub_sub_cancel, he₂, Ideal.mem_span_singleton]
  · rintro ⟨t, ht₁, ht₂⟩
    use 1 - t
    rw [← sub_sub_self 1 t] at ht₁; generalize 1 - t = e at *
    constructor
    · suffices e ∈ (Submodule.span (S ⊗[R] S) {1 - e}).annihilator by
        simpa [IsIdempotentElem, mul_sub, sub_eq_zero, eq_comm,
          Submodule.mem_annihilator_span_singleton] using this
      exact (show Ideal.span _ ≤ _ by simpa only [Ideal.span_le, Set.range_subset_iff,
        Submodule.mem_annihilator_span_singleton, SetLike.mem_coe]) ht₂
    · apply le_antisymm <;> simp only [Ideal.submodule_span_eq, Ideal.mem_span_singleton, ht₂,
        Ideal.span_le, Set.singleton_subset_iff, SetLike.mem_coe, Set.range_subset_iff]
      intro s
      use 1 ⊗ₜ[R] s - s ⊗ₜ[R] 1
      linear_combination ht₁ s

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

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 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
⊢ QuasiFiniteAt A q

Tactic:
let f : A ⊗[R] Localization.AtPrime p →ₐ[A] Localization.AtPrime q :=
    Algebra.TensorProduct.lift (Algebra.ofId _ _) ⟨Localization.localRingHom _ _ _ hq, by
      simp [IsScalarTower.algebraMap_apply R S (Localization.AtPrime p),
        IsScalarTower.algebraMap_apply R (A ⊗[R] S) (Localization.AtPrime q)]⟩ fun _ _ ↦ .all _ _

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 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
f : A ⊗[R] Localization.AtPrime p →ₐ[A] Localization.AtPrime q :=
  TensorProduct.lift (ofId A (Localization.AtPrime q))
    { toRingHom := Localization.localRingHom p q TensorProduct.includeRight.toRingHom hq, commutes' := ⋯ } ⋯
⊢ QuasiFiniteAt A q
Module: Mathlib.RingTheory.Etale.Basic

Goal state before:
pp: R : Type u
A : Type v
B : Type u_1
inst✝⁵ : CommRing R
inst✝⁴ : CommRing A
inst✝³ : Algebra R A
inst✝² : CommRing B
inst✝¹ : Algebra R B
S : Type u_2
inst✝ : CommRing S
⊢ Etale (R × S) R

Tactic:
algebraize [RingHom.fst R S]

Goal state after:
R : Type u
A : Type v
B : Type u_1
inst✝⁵ : CommRing R
inst✝⁴ : CommRing A
inst✝³ : Algebra R A
inst✝² : CommRing B
inst✝¹ : Algebra R B
S : Type u_2
inst✝ : CommRing S
algInst✝ : Algebra (R × S) R := (RingHom.fst R S).toAlgebra
⊢ Etale (R × S) R