mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.FieldTheory.IntermediateField.ExtendRight

Goal state before:
pp: K : Type u_1
L : Type u_2
inst✝¹³ : Field K
inst✝¹² : Field L
inst✝¹¹ : Algebra K L
F : IntermediateField K L
M : Type u_3
inst✝¹⁰ : Field M
inst✝⁹ : Algebra K M
inst✝⁸ : Algebra L M
inst✝⁷ : IsScalarTower K L M
R : Type u_4
S : Type u_5
inst✝⁶ : CommRing R
inst✝⁵ : CommRing S
inst✝⁴ : Algebra S ↥F
inst✝³ : Algebra S M
inst✝² : IsScalarTower S (↥F) M
inst✝¹ : Algebra S K
inst✝ : IsScalarTower S K M
⊢ (F.extendRight M).algebra' = algebra F M

Tactic:
rfl

Goal state after:
Module: Mathlib.FieldTheory.CardinalEmb

Goal state before:
pp: case pos
F : Type u
E : Type v
inst✝³ : Field F
inst✝² : Field E
inst✝¹ : Algebra F E
rank_inf : Fact (ℵ₀ ≤ Module.rank F E)
inst✝ : Algebra.IsAlgebraic F E
i : WithTop (Module.rank F E).ord.ToType
hi : IsSuccPrelimit i
f : failed to pretty print expression (use 'set_option pp.rawOnError true' for raw representation)
h : Nonempty ↑(Iio i)
x : E
hx✝ : x ∈ (filtration i).toSubalgebra
hx : ∃ i_1, x ∈ ↑(filtration ↑i_1)
⊢ (↑((fun f ↦ ⟨fun j ↦ embFunctor F E ⋯ f, ⋯⟩) f) hx.choose) ⟨↑⟨x, hx✝⟩, ⋯⟩ = f ⟨x, hx✝⟩

Tactic:
rfl

Goal state after:
Module: Mathlib.FieldTheory.CardinalEmb

Goal state before:
pp: case a
F : Type u
E : Type v
inst✝³ : Field F
inst✝² : Field E
inst✝¹ : Algebra F E
inst✝ : Algebra.IsSeparable F E
rank_inf : ℵ₀ ≤ Module.rank F E
this : Fact (ℵ₀ ≤ Module.rank F E)
⊢ (Cardinal.prod fun i ↦ #(Cardinal.factor ↑i)) ≤ ℵ₀ ^ Module.rank F E

Tactic:
conv_rhs => rw [← mk_ord_toType (Module.rank F E), ← prod_const']

Goal state after:
case a
F : Type u
E : Type v
inst✝³ : Field F
inst✝² : Field E
inst✝¹ : Algebra F E
inst✝ : Algebra.IsSeparable F E
rank_inf : ℵ₀ ≤ Module.rank F E
this : Fact (ℵ₀ ≤ Module.rank F E)
⊢ (Cardinal.prod fun i ↦ #(Cardinal.factor ↑i)) ≤ Cardinal.prod fun x ↦ ℵ₀
Module: Mathlib.FieldTheory.Galois.Profinite

Goal state before:
pp: k✝ : Type u_1
K✝ : Type u_2
inst✝⁵ : Field k✝
inst✝⁴ : Field K✝
inst✝³ : Algebra k✝ K✝
k : Type u_3
K : Type u_4
inst✝² : Field k
inst✝¹ : Field K
inst✝ : Algebra k K
⊢ ⟨fun L ↦ 1, ⋯⟩ = 1

Tactic:
rfl

Goal state after:
Module: Mathlib.FieldTheory.Galois.Profinite

Goal state before:
pp: k✝ : Type u_1
K✝ : Type u_2
inst✝⁵ : Field k✝
inst✝⁴ : Field K✝
inst✝³ : Algebra k✝ K✝
k : Type u_3
K : Type u_4
inst✝² : Field k
inst✝¹ : Field K
inst✝ : Algebra k K
x y : Gal(K/k)
⊢ ⟨fun L ↦
      (AlgEquiv.restrictNormalHom ↥(unop L).toIntermediateField) x *
        (AlgEquiv.restrictNormalHom ↥(unop L).toIntermediateField) y,
      ⋯⟩ =
    ⟨fun L ↦ (AlgEquiv.restrictNormalHom ↥(unop L).toIntermediateField) x, ⋯⟩ *
      ⟨fun L ↦ (AlgEquiv.restrictNormalHom ↥(unop L).toIntermediateField) y, ⋯⟩

Tactic:
rfl

Goal state after:
Module: Mathlib.FieldTheory.CardinalEmb

Goal state before:
pp: F : Type u
E : Type v
inst✝³ : Field F
inst✝² : Field E
inst✝¹ : Algebra F E
inst✝ : Algebra.IsAlgebraic F E
rank_inf : ℵ₀ ≤ sepDegree F E
⊢ 2 ^ Module.rank F ↥(separableClosure F E) = 2 ^ sepDegree F E

Tactic:
rfl

Goal state after:
Module: Mathlib.FieldTheory.CardinalEmb

Goal state before:
pp: F : Type u
E : Type v
inst✝³ : Field F
inst✝² : Field E
inst✝¹ : Algebra F E
inst✝ : Algebra.IsAlgebraic F E
⊢ (fun c ↦ if ℵ₀ ≤ c then 2 ^ c else c) (Module.rank F ↥(separableClosure F E)) =
    (fun c ↦ if ℵ₀ ≤ c then 2 ^ c else c) (sepDegree F E)

Tactic:
rfl

Goal state after:
Module: Mathlib.FieldTheory.PerfectClosure

Goal state before:
pp: K : Type u
inst✝² : CommRing K
p : ℕ
inst✝¹ : Fact (Nat.Prime p)
inst✝ : CharP K p
x1 x2 y : ℕ × K
H : R K p x1 x2
n : ℕ
x : K
⊢ R K p ((n, x).1 + y.1, (⇑(frobenius K p))^[y.1] (n, x).2 + (⇑(frobenius K p))^[(n, x).1] y.2)
    ((n + 1, (frobenius K p) x).1 + y.1,
      (⇑(frobenius K p))^[y.1] (n + 1, (frobenius K p) x).2 + (⇑(frobenius K p))^[(n + 1, (frobenius K p) x).1] y.2)

Tactic:
by
      rw [← iterate_succ_apply, iterate_succ_apply', iterate_succ_apply', ← map_add,
        Nat.succ_add]
      apply R.intro

Goal state after:
Module: Mathlib.FieldTheory.PerfectClosure

Goal state before:
pp: case zero
K : Type u
inst✝² : CommRing K
p : ℕ
inst✝¹ : Fact (Nat.Prime p)
inst✝ : CharP K p
⊢ mk K p (0, 0) = 0

Tactic:
rfl

Goal state after:
Module: Mathlib.FieldTheory.Galois.Profinite

Goal state before:
pp: case mk.mk
k : Type u_3
K : Type u_4
inst✝² : Field k
inst✝¹ : Field K
inst✝ : Algebra k K
g : ↑(limit (asProfiniteGaloisGroupFunctor k K)).toProfinite.toTop
L : IntermediateField k K
finiteDimensional✝¹ : FiniteDimensional k ↥L
isGalois✝¹ : IsGalois k ↥L
x : ↥{ toIntermediateField := L, finiteDimensional := finiteDimensional✝¹, isGalois := isGalois✝¹ }.toIntermediateField
L' : IntermediateField k K
finiteDimensional✝ : FiniteDimensional k ↥L'
isGalois✝ : IsGalois k ↥L'
h :
  { toIntermediateField := L, finiteDimensional := finiteDimensional✝¹, isGalois := isGalois✝¹ } ≤
    { toIntermediateField := L', finiteDimensional := finiteDimensional✝, isGalois := isGalois✝ }
this✝ : Algebra ↥L ↥L' := (Subsemiring.inclusion h).toAlgebra
this : IsScalarTower k ↥L ↥L' := IsScalarTower.of_algebraMap_eq (congrFun rfl)
⊢ (algebraMap (↥L') K)
      (((proj { toIntermediateField := L', finiteDimensional := finiteDimensional✝, isGalois := isGalois✝ }) g)
        ((algebraMap ↥L
            ↥{ toIntermediateField := L', finiteDimensional := finiteDimensional✝,
                  isGalois := isGalois✝ }.toIntermediateField)
          x)) =
    ↑(((proj { toIntermediateField := L', finiteDimensional := finiteDimensional✝, isGalois := isGalois✝ }) g) ⟨↑x, ⋯⟩)

Tactic:
rfl

Goal state after:
Module: Mathlib.FieldTheory.Galois.Profinite

Goal state before:
pp: k✝ : Type u_1
K✝ : Type u_2
inst✝⁶ : Field k✝
inst✝⁵ : Field K✝
inst✝⁴ : Algebra k✝ K✝
k : Type u_3
K : Type u_4
inst✝³ : Field k
inst✝² : Field K
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
g : ↑(limit (asProfiniteGaloisGroupFunctor k K)).toProfinite.toTop
x : K
L : FiniteGaloisIntermediateField k K := adjoin k {x, toAlgEquivAux g x}
⊢ toAlgEquivAux g⁻¹ (toAlgEquivAux g x) = x

Tactic:
have hx : x ∈ L.1 := subset_adjoin _ _ (Set.mem_insert x {toAlgEquivAux g x})

Goal state after:
k✝ : Type u_1
K✝ : Type u_2
inst✝⁶ : Field k✝
inst✝⁵ : Field K✝
inst✝⁴ : Algebra k✝ K✝
k : Type u_3
K : Type u_4
inst✝³ : Field k
inst✝² : Field K
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
g : ↑(limit (asProfiniteGaloisGroupFunctor k K)).toProfinite.toTop
x : K
L : FiniteGaloisIntermediateField k K := adjoin k {x, toAlgEquivAux g x}
hx : x ∈ L.toIntermediateField
⊢ toAlgEquivAux g⁻¹ (toAlgEquivAux g x) = x
Module: Mathlib.FieldTheory.IsRealClosed.Basic

Goal state before:
pp: case h
R : Type u
inst✝¹ : Field R
inst✝ : IsRealClosed R
n : ℕ
ih : ∀ m < n, ∀ {x : R}, IsSquare x → m ≠ 0 → ∃ r, x = r ^ m
x : R
hx : IsSquare x
hn : n ≠ 0
⊢ ∃ r, x = r ^ n

Tactic:
rcases Nat.even_or_odd n with (even | odd)

Goal state after:
case h.inl
R : Type u
inst✝¹ : Field R
inst✝ : IsRealClosed R
n : ℕ
ih : ∀ m < n, ∀ {x : R}, IsSquare x → m ≠ 0 → ∃ r, x = r ^ m
x : R
hx : IsSquare x
hn : n ≠ 0
even : Even n
⊢ ∃ r, x = r ^ n

case h.inr
R : Type u
inst✝¹ : Field R
inst✝ : IsRealClosed R
n : ℕ
ih : ∀ m < n, ∀ {x : R}, IsSquare x → m ≠ 0 → ∃ r, x = r ^ m
x : R
hx : IsSquare x
hn : n ≠ 0
odd : Odd n
⊢ ∃ r, x = r ^ n
Module: Mathlib.Topology.Algebra.Category.ProfiniteGrp.Basic

Goal state before:
pp: X✝ Y✝ Z : Type u
inst✝¹⁴ : Group X✝
inst✝¹³ : TopologicalSpace X✝
inst✝¹² : IsTopologicalGroup X✝
inst✝¹¹ : CompactSpace X✝
inst✝¹⁰ : TotallyDisconnectedSpace X✝
inst✝⁹ : Group Y✝
inst✝⁸ : TopologicalSpace Y✝
inst✝⁷ : IsTopologicalGroup Y✝
inst✝⁶ : CompactSpace Y✝
inst✝⁵ : TotallyDisconnectedSpace Y✝
inst✝⁴ : Group Z
inst✝³ : TopologicalSpace Z
inst✝² : IsTopologicalGroup Z
inst✝¹ : CompactSpace Z
inst✝ : TotallyDisconnectedSpace Z
X Y : ProfiniteGrp.{u_1}
f : X ⟶ Y
x✝ : IsIso ((forget₂ ProfiniteGrp.{u_1} Profinite).map f)
⊢ IsIso f

Tactic:
let i := asIso ((forget₂ ProfiniteGrp Profinite).map f)
    let e : X ≃ₜ* Y :=
      { CompHausLike.homeoOfIso i with
          map_mul' := map_mul f.hom }
    exact (ContinuousMulEquiv.toProfiniteGrpIso e).isIso_hom

Goal state after:
Module: Mathlib.FieldTheory.IsPerfectClosure

Goal state before:
pp: K : Type u_1
L : Type u_2
M : Type u_3
inst✝⁷ : CommRing K
inst✝⁶ : CommRing L
inst✝⁵ : CommRing M
i : K →+* L
j : K →+* M
p : ℕ
inst✝⁴ : ExpChar M p
inst✝³ : ExpChar K p
inst✝² : PerfectRing M p
inst✝¹ : IsPRadical i p
inst✝ : ExpChar L p
x : K
⊢ (iterateFrobeniusEquiv M p 0).symm (j x) = j x

Tactic:
iterateFrobeniusEquiv_zero

Goal state after:
K : Type u_1
L : Type u_2
M : Type u_3
inst✝⁷ : CommRing K
inst✝⁶ : CommRing L
inst✝⁵ : CommRing M
i : K →+* L
j : K →+* M
p : ℕ
inst✝⁴ : ExpChar M p
inst✝³ : ExpChar K p
inst✝² : PerfectRing M p
inst✝¹ : IsPRadical i p
inst✝ : ExpChar L p
x : K
⊢ (RingEquiv.refl M).symm (j x) = j x
Module: Mathlib.FieldTheory.PerfectClosure

Goal state before:
pp: case zero
K : Type u
inst✝² : CommRing K
p : ℕ
inst✝¹ : Fact (Nat.Prime p)
inst✝ : CharP K p
x : K
⊢ (⇑(frobenius (PerfectClosure K p) p))^[0] (mk K p (0, x)) = (of K p) x

Tactic:
rfl

Goal state after:
Module: Mathlib.FieldTheory.IsPerfectClosure

Goal state before:
pp: K : Type u_1
L : Type u_2
M : Type u_3
inst✝⁷ : CommRing K
inst✝⁶ : CommRing L
inst✝⁵ : CommRing M
i : K →+* L
j : K →+* M
p : ℕ
inst✝⁴ : ExpChar M p
inst✝³ : ExpChar K p
inst✝² : PerfectRing M p
inst✝¹ : IsPRadical i p
inst✝ : ExpChar L p
x : K
⊢ (RingEquiv.refl M).symm (j x) = j x

Tactic:
rfl

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

Goal state before:
pp: case inr
R : Type u
inst✝¹ : Field R
inst✝ : IsRealClosed R
x : R
hx : IsSquare x
n : ℕ
hk : -↑n ≠ 0
⊢ ∃ r, x = r ^ (-↑n)

Tactic:
· rcases exists_eq_pow_of_isSquare hx (by simpa using hk) with ⟨r, hr⟩
    exact ⟨r⁻¹, by simpa using hr⟩

Goal state after:
Module: Mathlib.FieldTheory.Isaacs

Goal state before:
pp: F : Type u_1
E : Type u_2
K : Type u_3
inst✝⁴ : Field F
inst✝³ : Field E
inst✝² : Field K
inst✝¹ : Algebra F E
inst✝ : Algebra F K
alg : Algebra.IsAlgebraic F E
h : ∀ (x : E), ∃ y, (aeval y) (minpoly F x) = 0
S : Finset E
p : K[X] := ∏ x ∈ S, Polynomial.map (algebraMap F K) (minpoly F x)
K' : Type u_3 := p.SplittingField
splits : ∀ s ∈ S, (Polynomial.map (algebraMap F K') (minpoly F s)).Splits
K₀ : IntermediateField F K' := restrictScalars F ⊥
FS : IntermediateField F E := adjoin F ↑S
Ω : Type (max u_2 u_3) := ↥FS →ₐ[F] K'
this : FiniteDimensional F ↥(adjoin F ↑S)
M : Ω → Submodule F ↥FS := fun ω ↦ Subalgebra.toSubmodule (comap ω K₀).toSubalgebra
x✝ : ↥FS
α : E
hα : α ∈ FS
β : K
hβ : (aeval β) (minpoly F α) = 0
ϕ : ↥F⟮α⟯ →ₐ[F] K' :=
  (IsScalarTower.toAlgHom F K K').comp
    ((AdjoinRoot.liftAlgHom (minpoly F α) (Algebra.ofId F K) β hβ).comp ↑(adjoinRootEquivAdjoin F ⋯).symm)
ω : ↥(adjoin F ↑S) →ₐ[F] K'
hω : ω.comp (inclusion ⋯) = ϕ
⊢ (IsScalarTower.toAlgHom F K K')
      ((AdjoinRoot.liftAlgHom (minpoly F α) (Algebra.ofId F K) β hβ)
        (↑(adjoinRootEquivAdjoin F ⋯).symm (AdjoinSimple.gen F α))) =
    (Algebra.ofId K K').toRingHom β

Tactic:
AlgEquiv.coe_toAlgHom,

Goal state after:
F : Type u_1
E : Type u_2
K : Type u_3
inst✝⁴ : Field F
inst✝³ : Field E
inst✝² : Field K
inst✝¹ : Algebra F E
inst✝ : Algebra F K
alg : Algebra.IsAlgebraic F E
h : ∀ (x : E), ∃ y, (aeval y) (minpoly F x) = 0
S : Finset E
p : K[X] := ∏ x ∈ S, Polynomial.map (algebraMap F K) (minpoly F x)
K' : Type u_3 := p.SplittingField
splits : ∀ s ∈ S, (Polynomial.map (algebraMap F K') (minpoly F s)).Splits
K₀ : IntermediateField F K' := restrictScalars F ⊥
FS : IntermediateField F E := adjoin F ↑S
Ω : Type (max u_2 u_3) := ↥FS →ₐ[F] K'
this : FiniteDimensional F ↥(adjoin F ↑S)
M : Ω → Submodule F ↥FS := fun ω ↦ Subalgebra.toSubmodule (comap ω K₀).toSubalgebra
x✝ : ↥FS
α : E
hα : α ∈ FS
β : K
hβ : (aeval β) (minpoly F α) = 0
ϕ : ↥F⟮α⟯ →ₐ[F] K' :=
  (IsScalarTower.toAlgHom F K K').comp
    ((AdjoinRoot.liftAlgHom (minpoly F α) (Algebra.ofId F K) β hβ).comp ↑(adjoinRootEquivAdjoin F ⋯).symm)
ω : ↥(adjoin F ↑S) →ₐ[F] K'
hω : ω.comp (inclusion ⋯) = ϕ
⊢ (IsScalarTower.toAlgHom F K K')
      ((AdjoinRoot.liftAlgHom (minpoly F α) (Algebra.ofId F K) β hβ)
        ((adjoinRootEquivAdjoin F ⋯).symm (AdjoinSimple.gen F α))) =
    (Algebra.ofId K K').toRingHom β
Module: Mathlib.FieldTheory.Isaacs

Goal state before:
pp: F : Type u_1
E : Type u_2
K : Type u_3
inst✝⁴ : Field F
inst✝³ : Field E
inst✝² : Field K
inst✝¹ : Algebra F E
inst✝ : Algebra F K
alg : Algebra.IsAlgebraic F E
h : ∀ (x : E), ∃ y, (aeval y) (minpoly F x) = 0
S : Finset E
p : K[X] := ∏ x ∈ S, Polynomial.map (algebraMap F K) (minpoly F x)
K' : Type u_3 := p.SplittingField
splits : ∀ s ∈ S, (Polynomial.map (algebraMap F K') (minpoly F s)).Splits
K₀ : IntermediateField F K' := restrictScalars F ⊥
FS : IntermediateField F E := adjoin F ↑S
Ω : Type (max u_2 u_3) := ↥FS →ₐ[F] K'
this : FiniteDimensional F ↥(adjoin F ↑S)
M : Ω → Submodule F ↥FS := fun ω ↦ Subalgebra.toSubmodule (comap ω K₀).toSubalgebra
x✝ : ↥FS
α : E
hα : α ∈ FS
β : K
hβ : (aeval β) (minpoly F α) = 0
ϕ : ↥F⟮α⟯ →ₐ[F] K' :=
  (IsScalarTower.toAlgHom F K K').comp
    ((AdjoinRoot.liftAlgHom (minpoly F α) (Algebra.ofId F K) β hβ).comp ↑(adjoinRootEquivAdjoin F ⋯).symm)
ω : ↥(adjoin F ↑S) →ₐ[F] K'
hω : ω.comp (inclusion ⋯) = ϕ
⊢ (IsScalarTower.toAlgHom F K K') β = (Algebra.ofId K K').toRingHom β

Tactic:
rfl

Goal state after:
Module: Mathlib.GroupTheory.CosetCover

Goal state before:
pp: G : Type u_1
inst✝ : Group G
ι : Type u_2
s : Finset ι
H : Subgroup G
g : ι → G
hcovers : ⋃ i ∈ s, g i • ↑H = Set.univ
hind : H.index = s.card
⊢ (↑s).PairwiseDisjoint fun x ↦ g x • ↑H

Tactic:
by
  have : Fintype (G ⧸ H) := fintypeOfIndexNeZero fun h => by
    rw [hind, Finset.card_eq_zero] at h
    rw [h, ← Finset.set_biUnion_coe, Finset.coe_empty, Set.biUnion_empty] at hcovers
    exact Set.empty_ne_univ hcovers
  suffices Function.Bijective (g · : s → G ⧸ H) by
    intro i hi j hj h' c hi' hj' x hx
    specialize hi' hx
    specialize hj' hx
    rw [mem_leftCoset_iff, SetLike.mem_coe, ← QuotientGroup.eq] at hi' hj'
    rw [ne_eq, ← Subtype.mk.injEq (p := (· ∈ (s : Set ι))) i hi j hj] at h'
    exact h' <| this.injective <| by simp only [hi', hj']
  rw [Fintype.bijective_iff_surjective_and_card]
  constructor
  · rwa [leftCoset_cover_const_iff_surjOn, Set.surjOn_iff_surjective] at hcovers
  · simp only [Fintype.card_coe, ← hind, index_eq_card, Nat.card_eq_fintype_card]

Goal state after:
Module: Mathlib.RingTheory.Algebraic.LinearIndependent

Goal state before:
pp: F : Type u_1
E : Type u_2
inst✝² : Field F
inst✝¹ : Field E
inst✝ : Algebra F E
x : E
H : ∀ (p : F[X]), (aeval x) p = 0 → p = 0
s : Finset F
m : F → F
i : F
hi : i ∈ s
hnz : ∀ (a : F), x - (algebraMap F E) a ≠ 0
b : E := ∏ j ∈ s, (x - (algebraMap F E) j)
h1 : ∀ i ∈ s, m i • (b * (x - (algebraMap F E) i)⁻¹) = m i • ∏ j ∈ s.erase i, (x - (algebraMap F E) j)
hm : ∑ x_1 ∈ s, m x_1 • ∏ j ∈ s.erase x_1, (x - (algebraMap F E) j) = 0
⊢ m i = 0

Tactic:
let p : Polynomial F := s.sum fun i ↦ .C (m i) * (s.erase i).prod fun j ↦ .X - .C j

Goal state after:
F : Type u_1
E : Type u_2
inst✝² : Field F
inst✝¹ : Field E
inst✝ : Algebra F E
x : E
H : ∀ (p : F[X]), (aeval x) p = 0 → p = 0
s : Finset F
m : F → F
i : F
hi : i ∈ s
hnz : ∀ (a : F), x - (algebraMap F E) a ≠ 0
b : E := ∏ j ∈ s, (x - (algebraMap F E) j)
h1 : ∀ i ∈ s, m i • (b * (x - (algebraMap F E) i)⁻¹) = m i • ∏ j ∈ s.erase i, (x - (algebraMap F E) j)
hm : ∑ x_1 ∈ s, m x_1 • ∏ j ∈ s.erase x_1, (x - (algebraMap F E) j) = 0
p : F[X] := ∑ i ∈ s, C (m i) * ∏ j ∈ s.erase i, (X - C j)
⊢ m i = 0
Module: Mathlib.FieldTheory.JacobsonNoether

Goal state before:
pp: D : Type u_1
inst✝¹ : DivisionRing D
inst✝ : Algebra.IsAlgebraic (↥k) D
H : k ≠ ⊤
p : ℕ
hp : ExpChar D p
insep : ∀ (x : D), IsSeparable (↥k) x → x ∈ k
a : D
ha : a ∉ k
ha₀ : a ≠ 0
b : D
hb1 : ((ad (↥k) D) a) b ≠ 0
n : ℕ
hn : 0 < n
c : D := (⇑((ad (↥k) D) a))^[n] b
hb : c ≠ 0 ∧ (⇑((ad (↥k) D) a))^[n + 1] b = 0
hc_def : c = (⇑((ad (↥k) D) a))^[n] b
x✝ : Invertible c := { invOf := c⁻¹, invOf_mul_self := ⋯, mul_invOf_self := ⋯ }
hc : a * c = c * a
d : D := c⁻¹ * a * (⇑((ad (↥k) D) a))^[n - 1] b
hd_def : d = c⁻¹ * a * (⇑((ad (↥k) D) a))^[n - 1] b
hc' : c⁻¹ * a = a * c⁻¹
⊢ a * (⇑((ad (↥k) D) a))^[n - Nat.succ 0 + Nat.succ 0 - 1] b -
      (⇑((ad (↥k) D) a))^[n - Nat.succ 0 + Nat.succ 0 - 1] b * a =
    ((ad (↥k) D) a) ((⇑((ad (↥k) D) a))^[n - Nat.succ 0] b)

Tactic:
rfl

Goal state after:
Module: Mathlib.FieldTheory.KummerExtension

Goal state before:
pp: K : Type u
inst✝ : Field K
n : ℕ
ζ : K
hζ : IsPrimitiveRoot ζ n
α a : K
hn : 0 < n
e : α ^ n = a
⊢ (Multiset.map ((fun x ↦ X - C x) ∘ fun x ↦ ζ ^ x * α) (Multiset.range n)).prod =
    ∏ i ∈ Finset.range n, (X - C (ζ ^ i * α))

Tactic:
rfl

Goal state after:
Module: Mathlib.GroupTheory.CosetCover

Goal state before:
pp: G : Type u_1
inst✝¹ : Group G
ι : Type u_2
H : ι → Subgroup G
g : ι → G
s : Finset ι
inst✝ : DecidablePred FiniteIndex
hcovers : ⋃ i ∈ {i ∈ s | (H i).FiniteIndex} ∪ {a ∈ s | ¬(H a).FiniteIndex}, g i • ↑(H i) = Set.univ
D : Subgroup G := ⨅ k ∈ {i ∈ s | (H i).FiniteIndex}, H k
hD : D.FiniteIndex
hD_le : ∀ {i : ι}, i ∈ s → (H i).FiniteIndex → D ≤ H i
t : (i : ι) → i ∈ s → (H i).FiniteIndex → Finset ↥(H i)
ht :
  ∀ (i : ι) (hi : i ∈ s) (hfi : (H i).FiniteIndex),
    IsComplement ↑(t i hi hfi) ↑(D.subgroupOf (H i)) ∧ ⋃ g ∈ t i hi hfi, ↑g • ↑D = ↑(H i)
κ : Type (max u_2 u_1) := (i : ↥s) × ↥(if h : (H ↑i).FiniteIndex then t ↑i ⋯ h else {1})
f : κ → G := fun k ↦ g ↑k.fst * ↑↑k.snd
K : κ → Subgroup G := fun k ↦ if (H ↑k.fst).FiniteIndex then D else H ↑k.fst
⊢ (⋃ x ∈ {k | (H ↑k.fst).FiniteIndex}, f x • ↑(K x)) ∪ ⋃ x ∈ {a | ¬(H ↑a.fst).FiniteIndex}, f x • ↑(K x) =
    (⋃ x ∈ {i ∈ s | (H i).FiniteIndex}, g x • ↑(H x)) ∪ ⋃ x ∈ {a ∈ s | ¬(H a).FiniteIndex}, g x • ↑(H x)

Tactic:
apply congrArg₂ (· ∪ ·) <;> rw [Set.iUnion_sigma, Set.iUnion_subtype]

Goal state after:
case hx
G : Type u_1
inst✝¹ : Group G
ι : Type u_2
H : ι → Subgroup G
g : ι → G
s : Finset ι
inst✝ : DecidablePred FiniteIndex
hcovers : ⋃ i ∈ {i ∈ s | (H i).FiniteIndex} ∪ {a ∈ s | ¬(H a).FiniteIndex}, g i • ↑(H i) = Set.univ
D : Subgroup G := ⨅ k ∈ {i ∈ s | (H i).FiniteIndex}, H k
hD : D.FiniteIndex
hD_le : ∀ {i : ι}, i ∈ s → (H i).FiniteIndex → D ≤ H i
t : (i : ι) → i ∈ s → (H i).FiniteIndex → Finset ↥(H i)
ht :
  ∀ (i : ι) (hi : i ∈ s) (hfi : (H i).FiniteIndex),
    IsComplement ↑(t i hi hfi) ↑(D.subgroupOf (H i)) ∧ ⋃ g ∈ t i hi hfi, ↑g • ↑D = ↑(H i)
κ : Type (max u_2 u_1) := (i : ↥s) × ↥(if h : (H ↑i).FiniteIndex then t ↑i ⋯ h else {1})
f : κ → G := fun k ↦ g ↑k.fst * ↑↑k.snd
K : κ → Subgroup G := fun k ↦ if (H ↑k.fst).FiniteIndex then D else H ↑k.fst
⊢ ⋃ x, ⋃ (hx : x ∈ s), ⋃ a, ⋃ (_ : ⟨⟨x, hx⟩, a⟩ ∈ {k | (H ↑k.fst).FiniteIndex}), f ⟨⟨x, hx⟩, a⟩ • ↑(K ⟨⟨x, hx⟩, a⟩) =
    ⋃ x ∈ {i ∈ s | (H i).FiniteIndex}, g x • ↑(H x)

case hy
G : Type u_1
inst✝¹ : Group G
ι : Type u_2
H : ι → Subgroup G
g : ι → G
s : Finset ι
inst✝ : DecidablePred FiniteIndex
hcovers : ⋃ i ∈ {i ∈ s | (H i).FiniteIndex} ∪ {a ∈ s | ¬(H a).FiniteIndex}, g i • ↑(H i) = Set.univ
D : Subgroup G := ⨅ k ∈ {i ∈ s | (H i).FiniteIndex}, H k
hD : D.FiniteIndex
hD_le : ∀ {i : ι}, i ∈ s → (H i).FiniteIndex → D ≤ H i
t : (i : ι) → i ∈ s → (H i).FiniteIndex → Finset ↥(H i)
ht :
  ∀ (i : ι) (hi : i ∈ s) (hfi : (H i).FiniteIndex),
    IsComplement ↑(t i hi hfi) ↑(D.subgroupOf (H i)) ∧ ⋃ g ∈ t i hi hfi, ↑g • ↑D = ↑(H i)
κ : Type (max u_2 u_1) := (i : ↥s) × ↥(if h : (H ↑i).FiniteIndex then t ↑i ⋯ h else {1})
f : κ → G := fun k ↦ g ↑k.fst * ↑↑k.snd
K : κ → Subgroup G := fun k ↦ if (H ↑k.fst).FiniteIndex then D else H ↑k.fst
⊢ ⋃ x, ⋃ (hx : x ∈ s), ⋃ a, ⋃ (_ : ⟨⟨x, hx⟩, a⟩ ∈ {a | ¬(H ↑a.fst).FiniteIndex}), f ⟨⟨x, hx⟩, a⟩ • ↑(K ⟨⟨x, hx⟩, a⟩) =
    ⋃ x ∈ {a ∈ s | ¬(H a).FiniteIndex}, g x • ↑(H x)
Module: Mathlib.FieldTheory.KummerExtension

Goal state before:
pp: K : Type u
inst✝ : Field K
p : ℕ
hp : Nat.Prime p
hp' : p ≠ 2
n : ℕ
a : K
ha : ∀ (b : K), b ^ p ≠ a
⊢ Irreducible (X ^ p ^ n - C a)

Tactic:
apply X_pow_sub_C_irreducible_of_odd (hp.odd_of_ne_two hp').pow
  intro q hq hq'
  simpa [(Nat.prime_dvd_prime_iff_eq hq hp).mp (hq.dvd_of_dvd_pow hq')] using ha

Goal state after:
Module: Mathlib.FieldTheory.KummerExtension

Goal state before:
pp: K : Type u
inst✝¹ : Field K
n : ℕ
hζ : (primitiveRoots n K).Nonempty
a : K
H : Irreducible (X ^ n - C a)
inst✝ : NeZero n
η : ↥(rootsOfUnity n K)
this : Fact (Irreducible (X ^ n - C a))
⊢ AdjoinRootXPowSubCEquivToRootsOfUnity hζ H ((↑(autAdjoinRootXPowSubC n a)).toFun η) = η

Tactic:
have : IsDomain K[n√a] := inferInstance

Goal state after:
K : Type u
inst✝¹ : Field K
n : ℕ
hζ : (primitiveRoots n K).Nonempty
a : K
H : Irreducible (X ^ n - C a)
inst✝ : NeZero n
η : ↥(rootsOfUnity n K)
this✝ : Fact (Irreducible (X ^ n - C a))
this : IsDomain K[n√a]
⊢ AdjoinRootXPowSubCEquivToRootsOfUnity hζ H ((↑(autAdjoinRootXPowSubC n a)).toFun η) = η
Module: Mathlib.FieldTheory.KummerExtension

Goal state before:
pp: K : Type u
inst✝³ : Field K
n : ℕ
hζ : (primitiveRoots n K).Nonempty
a : K
H : Irreducible (X ^ n - C a)
L : Type u_1
inst✝² : Field L
inst✝¹ : Algebra K L
inst✝ : IsSplittingField K L (X ^ n - C a)
α : L
hα : α ^ n = (algebraMap K L) a
⊢ K [↑(adjoinRootXPowSubCEquiv hζ H hα).symm α] = ⊤

Tactic:
AlgEquiv.coe_toAlgHom,

Goal state after:
K : Type u
inst✝³ : Field K
n : ℕ
hζ : (primitiveRoots n K).Nonempty
a : K
H : Irreducible (X ^ n - C a)
L : Type u_1
inst✝² : Field L
inst✝¹ : Algebra K L
inst✝ : IsSplittingField K L (X ^ n - C a)
α : L
hα : α ^ n = (algebraMap K L) a
⊢ K [(adjoinRootXPowSubCEquiv hζ H hα).symm α] = ⊤
Module: Mathlib.FieldTheory.KummerExtension

Goal state before:
pp: K : Type u
inst✝⁴ : Field K
n : ℕ
hζ : (primitiveRoots n K).Nonempty
a : K
H : Irreducible (X ^ n - C a)
L : Type u_1
inst✝³ : Field L
inst✝² : Algebra K L
inst✝¹ : IsSplittingField K L (X ^ n - C a)
inst✝ : NeZero n
η : ↥(rootsOfUnity n K)
⊢ ↑↑η • rootOfSplitsXPowSubC ⋯ a L = η • rootOfSplitsXPowSubC ⋯ a L

Tactic:
rfl

Goal state after:
Module: Mathlib.GroupTheory.CosetCover

Goal state before:
pp: case neg
G : Type u_1
inst✝¹ : Group G
ι : Type u_2
H : ι → Subgroup G
g : ι → G
s : Finset ι
hcovers : ⋃ i ∈ s, g i • ↑(H i) = Set.univ
inst✝ : DecidablePred FiniteIndex
D : Subgroup G := ⨅ k ∈ {i ∈ s | (H i).FiniteIndex}, H k
hD : D.FiniteIndex
hD_le : ∀ {i : ι}, i ∈ s → (H i).FiniteIndex → D ≤ H i
t : (i : ι) → i ∈ s → (H i).FiniteIndex → Finset ↥(H i)
ht :
  ∀ (i : ι) (hi : i ∈ s) (hfi : (H i).FiniteIndex),
    IsComplement ↑(t i hi hfi) ↑(D.subgroupOf (H i)) ∧ ⋃ g ∈ t i hi hfi, ↑g • ↑D = ↑(H i)
κ : Type (max u_2 u_1) := (i : ↥s) × ↥(if h : (H ↑i).FiniteIndex then t ↑i ⋯ h else {1})
f : κ → G := fun k ↦ g ↑k.fst * ↑↑k.snd
K : κ → Subgroup G := fun k ↦ if (H ↑k.fst).FiniteIndex then D else H ↑k.fst
k : κ
hkfi : (H ↑k.fst).FiniteIndex
hk : K k = D
hcovers' : ⋃ i ∈ {x | K x = D}, f i • ↑D = Set.univ
hHD : ∀ (i : ι), ¬(H i).FiniteIndex → H i ≠ D
i : ↥s
x✝ : i ∈ s.attach
hfi : ¬(H ↑i).FiniteIndex
⊢ ∑ s_1, ↑(if K ⟨i, s_1⟩ = D then 1 else 0) = 0⁻¹ * ↑D.index

Tactic:
inv_zero,

Goal state after:
case neg
G : Type u_1
inst✝¹ : Group G
ι : Type u_2
H : ι → Subgroup G
g : ι → G
s : Finset ι
hcovers : ⋃ i ∈ s, g i • ↑(H i) = Set.univ
inst✝ : DecidablePred FiniteIndex
D : Subgroup G := ⨅ k ∈ {i ∈ s | (H i).FiniteIndex}, H k
hD : D.FiniteIndex
hD_le : ∀ {i : ι}, i ∈ s → (H i).FiniteIndex → D ≤ H i
t : (i : ι) → i ∈ s → (H i).FiniteIndex → Finset ↥(H i)
ht :
  ∀ (i : ι) (hi : i ∈ s) (hfi : (H i).FiniteIndex),
    IsComplement ↑(t i hi hfi) ↑(D.subgroupOf (H i)) ∧ ⋃ g ∈ t i hi hfi, ↑g • ↑D = ↑(H i)
κ : Type (max u_2 u_1) := (i : ↥s) × ↥(if h : (H ↑i).FiniteIndex then t ↑i ⋯ h else {1})
f : κ → G := fun k ↦ g ↑k.fst * ↑↑k.snd
K : κ → Subgroup G := fun k ↦ if (H ↑k.fst).FiniteIndex then D else H ↑k.fst
k : κ
hkfi : (H ↑k.fst).FiniteIndex
hk : K k = D
hcovers' : ⋃ i ∈ {x | K x = D}, f i • ↑D = Set.univ
hHD : ∀ (i : ι), ¬(H i).FiniteIndex → H i ≠ D
i : ↥s
x✝ : i ∈ s.attach
hfi : ¬(H ↑i).FiniteIndex
⊢ ∑ s_1, ↑(if K ⟨i, s_1⟩ = D then 1 else 0) = 0 * ↑D.index