mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.RingTheory.AlgebraicIndependent.TranscendenceBasis

Goal state before:
pp: case inr.inr
ι : Type u
R : Type u_1
S : Type v
inst✝⁴ : CommRing R
inst✝³ : CommRing S
inst✝² : Algebra R S
inst✝¹ : FaithfulSMul R S
inst✝ : NoZeroDivisors S
s : Set ι
i j : ι
v : ι → S
hj✝ : j ∈ insert i s
H₁ : IsTranscendenceBasis R fun x ↦ v ↑x
this✝³ : Nontrivial ↥(adjoin R (v '' (insert i s \ {j})))
this✝² : Nontrivial S
this✝¹ : IsDomain S
H₂ : v j ∈ (matroid R S).closure (v '' insert i s \ {v j})
this✝ : Nontrivial R
inj : InjOn v s
H' : (matroid R S).IsBase (v '' s)
hj : j ∈ s
Hj : v j ∉ (matroid R S).closure (v '' s \ {v j})
hi : i ∉ s
ne : v i ≠ v j
hi' : v i ∉ v '' s
this : InjOn v (insert i s)
⊢ (matroid R S).IsBase (v '' insert i s \ {v j})

Tactic:
image_insert_eq

Goal state after:
case inr.inr
ι : Type u
R : Type u_1
S : Type v
inst✝⁴ : CommRing R
inst✝³ : CommRing S
inst✝² : Algebra R S
inst✝¹ : FaithfulSMul R S
inst✝ : NoZeroDivisors S
s : Set ι
i j : ι
v : ι → S
hj✝ : j ∈ insert i s
H₁ : IsTranscendenceBasis R fun x ↦ v ↑x
this✝³ : Nontrivial ↥(adjoin R (v '' (insert i s \ {j})))
this✝² : Nontrivial S
this✝¹ : IsDomain S
H₂ : v j ∈ (matroid R S).closure (insert (v i) (v '' s) \ {v j})
this✝ : Nontrivial R
inj : InjOn v s
H' : (matroid R S).IsBase (v '' s)
hj : j ∈ s
Hj : v j ∉ (matroid R S).closure (v '' s \ {v j})
hi : i ∉ s
ne : v i ≠ v j
hi' : v i ∉ v '' s
this : InjOn v (insert i s)
⊢ (matroid R S).IsBase (insert (v i) (v '' s) \ {v j})
Module: Mathlib.FieldTheory.Galois.Basic

Goal state before:
pp: F : Type u_1
inst✝⁴ : Field F
E : Type u_2
inst✝³ : Field E
inst✝² : Algebra F E
inst✝¹ : FiniteDimensional F E
inst✝ : IsGalois F E
α : E
hα : F⟮α⟯ = ⊤
iso : ↥F⟮α⟯ ≃ₐ[F] E :=
  { toFun := fun e ↦ ↑e, invFun := fun e ↦ ⟨e, ⋯⟩, left_inv := ⋯, right_inv := ⋯, map_mul' := ⋯, map_add' := ⋯,
    commutes' := ⋯ }
H : IsIntegral F α
h_sep : IsSeparable F α
h_splits : (Polynomial.map (algebraMap F E) (minpoly F α)).Splits
⊢ (Polynomial.map (algebraMap F ↥F⟮α⟯) (minpoly F α)).Splits

Tactic:
simpa [Polynomial.map_map] using! h_splits.map iso.symm.toRingHom

Goal state after:
Module: Mathlib.Topology.Algebra.FilterBasis

Goal state before:
pp: R : Type u_1
M : Type u_2
inst✝⁴ : Semiring R
inst✝³ : TopologicalSpace R
inst✝² : AddCommGroup M
inst✝¹ : Module R M
B : ModuleFilterBasis R M
inst✝ : DiscreteTopology R
x₀ : R
U : Set M
h : U ∈ {{0}}
⊢ ∃
    V ∈
      (have this := default;
        this).sets,
    V ⊆ (fun x ↦ x₀ • x) ⁻¹' U

Tactic:
rw [mem_singleton_iff] at h

Goal state after:
R : Type u_1
M : Type u_2
inst✝⁴ : Semiring R
inst✝³ : TopologicalSpace R
inst✝² : AddCommGroup M
inst✝¹ : Module R M
B : ModuleFilterBasis R M
inst✝ : DiscreteTopology R
x₀ : R
U : Set M
h : U = {0}
⊢ ∃
    V ∈
      (have this := default;
        this).sets,
    V ⊆ (fun x ↦ x₀ • x) ⁻¹' U
Module: Mathlib.Topology.Algebra.FilterBasis

Goal state before:
pp: case hmul
R : Type u_1
M : Type u_2
inst✝⁶ : Ring R
inst✝⁵ : TopologicalSpace R
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
ι : Type u_3
inst✝² : IsTopologicalRing R
inst✝¹ : TopologicalSpace M
inst✝ : IsTopologicalAddGroup M
p : ι → Prop
b : ι → Set M
h : (𝓝 0).HasBasis p b
hsmul : ∀ {i : ι}, p i → ∃ V ∈ 𝓝 0, ∃ j, p j ∧ V • b j ⊆ b i
hsmul_left : ∀ (x₀ : R) {i : ι}, p i → ∃ j, p j ∧ MapsTo (fun x ↦ x₀ • x) (b j) (b i)
hsmul_right : ∀ (m₀ : M) {i : ι}, p i → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ b i
i : ι
⊢ p i → ∀ᶠ (x : R × M) in 𝓝 0 ×ˢ 𝓝 0, x.1 • x.2 ∈ b i

Tactic:
hi

Goal state after:
case hmul
R : Type u_1
M : Type u_2
inst✝⁶ : Ring R
inst✝⁵ : TopologicalSpace R
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
ι : Type u_3
inst✝² : IsTopologicalRing R
inst✝¹ : TopologicalSpace M
inst✝ : IsTopologicalAddGroup M
p : ι → Prop
b : ι → Set M
h : (𝓝 0).HasBasis p b
hsmul : ∀ {i : ι}, p i → ∃ V ∈ 𝓝 0, ∃ j, p j ∧ V • b j ⊆ b i
hsmul_left : ∀ (x₀ : R) {i : ι}, p i → ∃ j, p j ∧ MapsTo (fun x ↦ x₀ • x) (b j) (b i)
hsmul_right : ∀ (m₀ : M) {i : ι}, p i → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ b i
i : ι
hi : p i
⊢ ∀ᶠ (x : R × M) in 𝓝 0 ×ˢ 𝓝 0, x.1 • x.2 ∈ b i
Module: Mathlib.Topology.Algebra.FilterBasis

Goal state before:
pp: case hmulleft
R : Type u_1
M : Type u_2
inst✝⁶ : Ring R
inst✝⁵ : TopologicalSpace R
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
ι : Type u_3
inst✝² : IsTopologicalRing R
inst✝¹ : TopologicalSpace M
inst✝ : IsTopologicalAddGroup M
p : ι → Prop
b : ι → Set M
h : (𝓝 0).HasBasis p b
hsmul : ∀ {i : ι}, p i → ∃ V ∈ 𝓝 0, ∃ j, p j ∧ V • b j ⊆ b i
hsmul_left : ∀ (x₀ : R) {i : ι}, p i → ∃ j, p j ∧ MapsTo (fun x ↦ x₀ • x) (b j) (b i)
hsmul_right : ∀ (m₀ : M) {i : ι}, p i → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ b i
⊢ ∀ (m : M), Tendsto (fun a ↦ a • m) (𝓝 0) (𝓝 0)

Tactic:
intro m₀

Goal state after:
case hmulleft
R : Type u_1
M : Type u_2
inst✝⁶ : Ring R
inst✝⁵ : TopologicalSpace R
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
ι : Type u_3
inst✝² : IsTopologicalRing R
inst✝¹ : TopologicalSpace M
inst✝ : IsTopologicalAddGroup M
p : ι → Prop
b : ι → Set M
h : (𝓝 0).HasBasis p b
hsmul : ∀ {i : ι}, p i → ∃ V ∈ 𝓝 0, ∃ j, p j ∧ V • b j ⊆ b i
hsmul_left : ∀ (x₀ : R) {i : ι}, p i → ∃ j, p j ∧ MapsTo (fun x ↦ x₀ • x) (b j) (b i)
hsmul_right : ∀ (m₀ : M) {i : ι}, p i → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ b i
m₀ : M
⊢ Tendsto (fun a ↦ a • m₀) (𝓝 0) (𝓝 0)
Module: Mathlib.Topology.Algebra.FilterBasis

Goal state before:
pp: case hmulleft
R : Type u_1
M : Type u_2
inst✝⁶ : Ring R
inst✝⁵ : TopologicalSpace R
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
ι : Type u_3
inst✝² : IsTopologicalRing R
inst✝¹ : TopologicalSpace M
inst✝ : IsTopologicalAddGroup M
p : ι → Prop
b : ι → Set M
h : (𝓝 0).HasBasis p b
hsmul : ∀ {i : ι}, p i → ∃ V ∈ 𝓝 0, ∃ j, p j ∧ V • b j ⊆ b i
hsmul_left : ∀ (x₀ : R) {i : ι}, p i → ∃ j, p j ∧ MapsTo (fun x ↦ x₀ • x) (b j) (b i)
hsmul_right : ∀ (m₀ : M) {i : ι}, p i → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ b i
m₀ : M
i : ι
⊢ p i → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ b i

Tactic:
hi

Goal state after:
case hmulleft
R : Type u_1
M : Type u_2
inst✝⁶ : Ring R
inst✝⁵ : TopologicalSpace R
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
ι : Type u_3
inst✝² : IsTopologicalRing R
inst✝¹ : TopologicalSpace M
inst✝ : IsTopologicalAddGroup M
p : ι → Prop
b : ι → Set M
h : (𝓝 0).HasBasis p b
hsmul : ∀ {i : ι}, p i → ∃ V ∈ 𝓝 0, ∃ j, p j ∧ V • b j ⊆ b i
hsmul_left : ∀ (x₀ : R) {i : ι}, p i → ∃ j, p j ∧ MapsTo (fun x ↦ x₀ • x) (b j) (b i)
hsmul_right : ∀ (m₀ : M) {i : ι}, p i → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ b i
m₀ : M
i : ι
hi : p i
⊢ ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ b i
Module: Mathlib.Topology.Algebra.FilterBasis

Goal state before:
pp: case hmulright
R : Type u_1
M : Type u_2
inst✝⁶ : Ring R
inst✝⁵ : TopologicalSpace R
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
ι : Type u_3
inst✝² : IsTopologicalRing R
inst✝¹ : TopologicalSpace M
inst✝ : IsTopologicalAddGroup M
p : ι → Prop
b : ι → Set M
h : (𝓝 0).HasBasis p b
hsmul : ∀ {i : ι}, p i → ∃ V ∈ 𝓝 0, ∃ j, p j ∧ V • b j ⊆ b i
hsmul_left : ∀ (x₀ : R) {i : ι}, p i → ∃ j, p j ∧ MapsTo (fun x ↦ x₀ • x) (b j) (b i)
hsmul_right : ∀ (m₀ : M) {i : ι}, p i → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ b i
x₀ : R
i : ι
⊢ p i → ∀ᶠ (x : M) in 𝓝 0, x₀ • x ∈ b i

Tactic:
hi

Goal state after:
case hmulright
R : Type u_1
M : Type u_2
inst✝⁶ : Ring R
inst✝⁵ : TopologicalSpace R
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
ι : Type u_3
inst✝² : IsTopologicalRing R
inst✝¹ : TopologicalSpace M
inst✝ : IsTopologicalAddGroup M
p : ι → Prop
b : ι → Set M
h : (𝓝 0).HasBasis p b
hsmul : ∀ {i : ι}, p i → ∃ V ∈ 𝓝 0, ∃ j, p j ∧ V • b j ⊆ b i
hsmul_left : ∀ (x₀ : R) {i : ι}, p i → ∃ j, p j ∧ MapsTo (fun x ↦ x₀ • x) (b j) (b i)
hsmul_right : ∀ (m₀ : M) {i : ι}, p i → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ b i
x₀ : R
i : ι
hi : p i
⊢ ∀ᶠ (x : M) in 𝓝 0, x₀ • x ∈ b i
Module: Mathlib.Topology.Algebra.FilterBasis

Goal state before:
pp: R : Type u_1
M : Type u_2
inst✝³ : Ring R
inst✝² : TopologicalSpace R
inst✝¹ : AddCommGroup M
inst✝ : Module R M
B : ModuleFilterBasis R M
BR : RingFilterBasis R
BM : AddGroupFilterBasis M
smul : ∀ {U : Set M}, U ∈ BM → ∃ V ∈ BR, ∃ W ∈ BM, V • W ⊆ U
smul_left : ∀ (x₀ : R) {U : Set M}, U ∈ BM → ∃ V ∈ BM, V ⊆ (fun x ↦ x₀ • x) ⁻¹' U
smul_right : ∀ (m₀ : M) {U : Set M}, U ∈ BM → ∃ V ∈ BR, V ⊆ (fun x ↦ x • m₀) ⁻¹' U
x✝ : TopologicalSpace R := BR.topology
⊢ ∀ (m₀ : M) {U : Set M}, U ∈ BM.sets → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ U

Tactic:
intro m₀

Goal state after:
R : Type u_1
M : Type u_2
inst✝³ : Ring R
inst✝² : TopologicalSpace R
inst✝¹ : AddCommGroup M
inst✝ : Module R M
B : ModuleFilterBasis R M
BR : RingFilterBasis R
BM : AddGroupFilterBasis M
smul : ∀ {U : Set M}, U ∈ BM → ∃ V ∈ BR, ∃ W ∈ BM, V • W ⊆ U
smul_left : ∀ (x₀ : R) {U : Set M}, U ∈ BM → ∃ V ∈ BM, V ⊆ (fun x ↦ x₀ • x) ⁻¹' U
smul_right : ∀ (m₀ : M) {U : Set M}, U ∈ BM → ∃ V ∈ BR, V ⊆ (fun x ↦ x • m₀) ⁻¹' U
x✝ : TopologicalSpace R := BR.topology
m₀ : M
⊢ ∀ {U : Set M}, U ∈ BM.sets → ∀ᶠ (x : R) in 𝓝 0, x • m₀ ∈ U
Module: Mathlib.FieldTheory.Galois.Basic

Goal state before:
pp: case inr
F : Type u_1
E' : Type u_3
inst✝³ : Field F
inst✝² : Field E'
inst✝¹ : Algebra F E'
L : IntermediateField F E'
inst✝ : IsGalois F E'
this : ∀ (L : IntermediateField F E'), FiniteDimensional F ↥L → finrank F ↥L = L.fixingSubgroup.index
hnfd : ¬FiniteDimensional F ↥L
h : 0 ≠ L.fixingSubgroup.index
⊢ False

Tactic:
replace h : L.fixingSubgroup.FiniteIndex := ⟨h.symm⟩

Goal state after:
case inr
F : Type u_1
E' : Type u_3
inst✝³ : Field F
inst✝² : Field E'
inst✝¹ : Algebra F E'
L : IntermediateField F E'
inst✝ : IsGalois F E'
this : ∀ (L : IntermediateField F E'), FiniteDimensional F ↥L → finrank F ↥L = L.fixingSubgroup.index
hnfd : ¬FiniteDimensional F ↥L
h : L.fixingSubgroup.FiniteIndex
⊢ False
Module: Mathlib.LinearAlgebra.BilinearForm.DualLattice

Goal state before:
pp: case a
R : Type u_4
S : Type u_2
M : Type u_3
inst✝⁸ : CommRing R
inst✝⁷ : Field S
inst✝⁶ : AddCommGroup M
inst✝⁵ : Algebra R S
inst✝⁴ : Module R M
inst✝³ : Module S M
inst✝² : IsScalarTower R S M
B : BilinForm S M
ι : Type u_1
inst✝¹ : Finite ι
inst✝ : DecidableEq ι
hB : B.Nondegenerate
b : Basis ι S M
val✝ : Fintype ι
⊢ Submodule.span R (Set.range ⇑(B.dualBasis hB b)) ≤ B.dualSubmodule (Submodule.span R (Set.range ⇑b))

Tactic:
rw [Submodule.span_le]

Goal state after:
case a
R : Type u_4
S : Type u_2
M : Type u_3
inst✝⁸ : CommRing R
inst✝⁷ : Field S
inst✝⁶ : AddCommGroup M
inst✝⁵ : Algebra R S
inst✝⁴ : Module R M
inst✝³ : Module S M
inst✝² : IsScalarTower R S M
B : BilinForm S M
ι : Type u_1
inst✝¹ : Finite ι
inst✝ : DecidableEq ι
hB : B.Nondegenerate
b : Basis ι S M
val✝ : Fintype ι
⊢ Set.range ⇑(B.dualBasis hB b) ⊆ ↑(B.dualSubmodule (Submodule.span R (Set.range ⇑b)))
Module: Mathlib.RingTheory.Polynomial.GaussLemma

Goal state before:
pp: R : Type u_1
inst✝⁴ : CommRing R
K : Type u_2
inst✝³ : Field K
inst✝² : Algebra R K
inst✝¹ : IsFractionRing R K
inst✝ : IsIntegrallyClosed R
p : R[X]
h : p.Monic
hp : Irreducible p
a b : K[X]
H : Polynomial.map (algebraMap R K) p = a * b
hₐ : ¬IsUnit a
a' : R[X]
ha : Polynomial.map (algebraMap R K) a' * C a.leadingCoeff = a
b' : R[X]
hb : Polynomial.map (algebraMap R K) b' * C b.leadingCoeff = b
this : a.leadingCoeff * b.leadingCoeff = 1
⊢ IsUnit b

Tactic:
← ha,

Goal state after:
R : Type u_1
inst✝⁴ : CommRing R
K : Type u_2
inst✝³ : Field K
inst✝² : Algebra R K
inst✝¹ : IsFractionRing R K
inst✝ : IsIntegrallyClosed R
p : R[X]
h : p.Monic
hp : Irreducible p
a b : K[X]
hₐ : ¬IsUnit a
a' : R[X]
H : Polynomial.map (algebraMap R K) p = Polynomial.map (algebraMap R K) a' * C a.leadingCoeff * b
ha : Polynomial.map (algebraMap R K) a' * C a.leadingCoeff = a
b' : R[X]
hb : Polynomial.map (algebraMap R K) b' * C b.leadingCoeff = b
this : a.leadingCoeff * b.leadingCoeff = 1
⊢ IsUnit b
Module: Mathlib.RingTheory.Polynomial.GaussLemma

Goal state before:
pp: case refine_2
R : Type u_1
inst✝⁴ : CommRing R
K : Type u_2
inst✝³ : Field K
inst✝² : Algebra R K
inst✝¹ : IsFractionRing R K
inst✝ : IsIntegrallyClosed R
p : R[X]
h : p.Monic
hp : Irreducible p
a b : K[X]
hₐ : ¬IsUnit a
a' : R[X]
ha : Polynomial.map (algebraMap R K) a' * C a.leadingCoeff = a
b' : R[X]
H : Polynomial.map (algebraMap R K) p = Polynomial.map (algebraMap R K) (a' * b')
hb : Polynomial.map (algebraMap R K) b' * C b.leadingCoeff = b
this : a.leadingCoeff * b.leadingCoeff = 1
h_contra : IsUnit a'
⊢ IsUnit a

Tactic:
← ha,

Goal state after:
case refine_2
R : Type u_1
inst✝⁴ : CommRing R
K : Type u_2
inst✝³ : Field K
inst✝² : Algebra R K
inst✝¹ : IsFractionRing R K
inst✝ : IsIntegrallyClosed R
p : R[X]
h : p.Monic
hp : Irreducible p
a b : K[X]
hₐ : ¬IsUnit a
a' : R[X]
ha : Polynomial.map (algebraMap R K) a' * C a.leadingCoeff = a
b' : R[X]
H : Polynomial.map (algebraMap R K) p = Polynomial.map (algebraMap R K) (a' * b')
hb : Polynomial.map (algebraMap R K) b' * C b.leadingCoeff = b
this : a.leadingCoeff * b.leadingCoeff = 1
h_contra : IsUnit a'
⊢ IsUnit (Polynomial.map (algebraMap R K) a' * C a.leadingCoeff)
Module: Mathlib.FieldTheory.Minpoly.MinpolyDiv

Goal state before:
pp: case a
R : Type u_2
S : Type u_1
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
x : S
hx : IsIntegral R x
a✝ : Nontrivial S
⊢ Submodule.span R (Set.range (minpolyDiv R x).coeff) ≤ Subalgebra.toSubmodule R[x]

Tactic:
rw [Submodule.span_le]

Goal state after:
case a
R : Type u_2
S : Type u_1
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
x : S
hx : IsIntegral R x
a✝ : Nontrivial S
⊢ Set.range (minpolyDiv R x).coeff ⊆ ↑(Subalgebra.toSubmodule R[x])
Module: Mathlib.FieldTheory.Galois.Infinite

Goal state before:
pp: k : Type u_1
K : Type u_2
inst✝³ : Field k
inst✝² : Field K
inst✝¹ : Algebra k K
H : ClosedSubgroup Gal(K/k)
inst✝ : IsGalois k K
σ : Gal(K/k)
hσ : σ ∈ (fixedField ↑H).fixingSubgroup
h✝ : σ ∉ ↑H
b : Set Gal(K/k)
sub : b ⊆ (fun y ↦ σ * y) ⁻¹' (↑H).carrierᶜ
gp : Subgroup Gal(K/k)
L : IntermediateField k K
eq✝ : (fun g ↦ g.carrier) L.fixingSubgroup = b
hL : L ∈ finiteExts k K
eq' : L.fixingSubgroup = gp
this : FiniteDimensional k ↥L
L' : FiniteGaloisIntermediateField k K :=
  let __src := normalClosure k (↥L) K;
  { toIntermediateField := __src, finiteDimensional := ⋯, isGalois := ⋯ }
compl : σ • L'.fixingSubgroup.carrier ⊆ (↑H).carrierᶜ
fix : ∀ x ∈ lift (fixedField (Subgroup.map (restrictNormalHom ↥L'.toIntermediateField) ↑H)), σ x = x
h : Gal(K/k)
mem : h ∈ ↑↑H
eq : (restrictNormalHom ↥L'.toIntermediateField) h = (restrictNormalHom ↥L'.toIntermediateField) σ
⊢ h ∈ σ • L'.fixingSubgroup.carrier

Tactic:
use σ⁻¹ * h

Goal state after:
case h
k : Type u_1
K : Type u_2
inst✝³ : Field k
inst✝² : Field K
inst✝¹ : Algebra k K
H : ClosedSubgroup Gal(K/k)
inst✝ : IsGalois k K
σ : Gal(K/k)
hσ : σ ∈ (fixedField ↑H).fixingSubgroup
h✝ : σ ∉ ↑H
b : Set Gal(K/k)
sub : b ⊆ (fun y ↦ σ * y) ⁻¹' (↑H).carrierᶜ
gp : Subgroup Gal(K/k)
L : IntermediateField k K
eq✝ : (fun g ↦ g.carrier) L.fixingSubgroup = b
hL : L ∈ finiteExts k K
eq' : L.fixingSubgroup = gp
this : FiniteDimensional k ↥L
L' : FiniteGaloisIntermediateField k K := ⋯
compl : σ • L'.fixingSubgroup.carrier ⊆ (↑H).carrierᶜ
fix : ∀ x ∈ lift (fixedField (Subgroup.map (restrictNormalHom ↥L'.toIntermediateField) ↑H)), σ x = x
h : Gal(K/k)
mem : h ∈ ↑↑H
eq : (restrictNormalHom ↥L'.toIntermediateField) h = (restrictNormalHom ↥L'.toIntermediateField) σ
⊢ σ⁻¹ * h ∈ L'.fixingSubgroup.carrier ∧ (fun x ↦ σ • x) (σ⁻¹ * h) = h
Module: Mathlib.FieldTheory.Minpoly.MinpolyDiv

Goal state before:
pp: R : Type u_2
S : Type u_1
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
x : S
⊢ (minpolyDiv R x).natDegree = (minpoly R x).natDegree - 1

Tactic:
nontriviality S
  by_cases hx : IsIntegral R x
  · rw [← natDegree_minpolyDiv_succ hx]; rfl
  · rw [minpolyDiv_eq_zero hx, minpoly.eq_zero hx]; rfl

Goal state after:
Module: Mathlib.FieldTheory.IsSepClosed

Goal state before:
pp: k : Type u
inst✝¹ : Field k
inst✝ : IsSepClosed k
n : ℕ
a b c : k
hn : ↑n = 0
hn' : 2 ≤ n
hb : b ≠ 0
⊢ ∃ x, a * x ^ n + b * x + c = 0

Tactic:
by
  let f : k[X] := C a * X ^ n + C b * X + C c
  -- Specify `n := 0` below, otherwise Lean unfolds `0` to `Zero.zero`.
  have hdeg : f.degree ≠ 0 := degree_ne_of_natDegree_ne (n := 0) <| by
    have : C 0 * X ^ n + C b * X = 0 * X ^ n + C b * X := by grind
    by_cases ha : a = 0
    · grind [zero_add]
    · grind [natDegree_add_eq_left_of_natDegree_lt]
  have hsep : f.Separable := separable_C_mul_X_pow_add_C_mul_X_add_C a b c hn hb.isUnit
  obtain ⟨x, hx⟩ := exists_root f hdeg hsep
  exact ⟨x, by simpa [f] using hx⟩

Goal state after:
Module: Mathlib.RingTheory.Polynomial.GaussLemma

Goal state before:
pp: R : Type u_1
inst✝⁵ : CommRing R
K : Type u_2
inst✝⁴ : Field K
inst✝³ : Algebra R K
inst✝² : IsFractionRing R K
inst✝¹ : IsDomain R
inst✝ : IsGCDMonoid R
f : R[X]
hf : f.IsPrimitive
g : K[X]
⊢ map (algebraMap R K) f * g ∈ lifts (algebraMap R K) ↔ g ∈ lifts (algebraMap R K)

Tactic:
rw [mul_comm, hf.mul_map_mem_lifts_iff]

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

Goal state before:
pp: k : Type u_1
K : Type u_2
R : Type u_3
inst✝⁵ : Field k
inst✝⁴ : Field K
inst✝³ : Algebra k K
inst✝² : CommRing R
inst✝¹ : Algebra k R
inst✝ : IsPurelyInseparable k K
x : R ⊗[k] K
q : ℕ := ringExpChar k
n : ℕ
hr : x ^ q ^ n ∈ (algebraMap R (R ⊗[k] K)).range
⊢ 0 < q

Tactic:
obtain (hq | hq) := expChar_is_prime_or_one k q <;> simp [hq, Nat.Prime.pos]

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

Goal state before:
pp: A : Type u_1
B : Type u_2
G : Type u_3
inst✝⁷ : CommRing A
inst✝⁶ : CommRing B
inst✝⁵ : Algebra A B
inst✝⁴ : Group G
inst✝³ : MulSemiringAction G B
inst✝² : IsInvariant A B G
inst✝¹ : Finite G
inst✝ : SMulCommClass G A B
P✝ Q✝ : Ideal B
hP✝ : P✝.IsPrime
hQ✝ : Q✝.IsPrime
hPQ✝ : Ideal.under A P✝ = Ideal.under A Q✝
val✝ : Fintype G
P Q : Ideal B
hP : P.IsPrime
hQ : Q.IsPrime
hPQ : Ideal.under A P = Ideal.under A Q
b : B
hb : b ∈ ↑Q
a : A
ha : (algebraMap A B) a = ∏ g, g • b
⊢ ∏ i, i • b ∈ P

Tactic:
← ha,

Goal state after:
A : Type u_1
B : Type u_2
G : Type u_3
inst✝⁷ : CommRing A
inst✝⁶ : CommRing B
inst✝⁵ : Algebra A B
inst✝⁴ : Group G
inst✝³ : MulSemiringAction G B
inst✝² : IsInvariant A B G
inst✝¹ : Finite G
inst✝ : SMulCommClass G A B
P✝ Q✝ : Ideal B
hP✝ : P✝.IsPrime
hQ✝ : Q✝.IsPrime
hPQ✝ : Ideal.under A P✝ = Ideal.under A Q✝
val✝ : Fintype G
P Q : Ideal B
hP : P.IsPrime
hQ : Q.IsPrime
hPQ : Ideal.under A P = Ideal.under A Q
b : B
hb : b ∈ ↑Q
a : A
ha : (algebraMap A B) a = ∏ g, g • b
⊢ (algebraMap A B) a ∈ P
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
⊢ (h⁻¹ • h • (a - eval b r) - h⁻¹ • if h • Q = Q then a else 0) ∈ h⁻¹ • Q

Tactic:
inv_smul_smul

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
⊢ (a - eval b r - h⁻¹ • if h • Q = Q then a else 0) ∈ h⁻¹ • Q
Module: Mathlib.RingTheory.Trace.Basic

Goal state before:
pp: 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
⊢ trace K L = 0

Tactic:
obtain ⟨p, hp⟩ := ExpChar.exists K
  have := expChar_ne_zero K p
  ext x
  by_cases h₀ : FiniteDimensional K L; swap
  · rw [trace_eq_zero_of_not_exists_basis]
    rintro ⟨s, ⟨b⟩⟩
    exact h₀ (Module.Finite.of_basis b)
  by_cases hx : IsSeparable K x
  · lift x to separableClosure K L using hx
    rw [← IntermediateField.algebraMap_apply, ← trace_trace (S := separableClosure K L),
      trace_algebraMap]
    obtain ⟨n, hn⟩ := IsPurelyInseparable.finrank_eq_pow (separableClosure K L) L p
    cases n with
    | zero =>
      rw [pow_zero, IntermediateField.finrank_eq_one_iff_eq_top, separableClosure.eq_top_iff] at hn
      cases H hn
    | succ n =>
      cases hp with
      | zero =>
        rw [one_pow, IntermediateField.finrank_eq_one_iff_eq_top, separableClosure.eq_top_iff] at hn
        cases H hn
      | prime hprime =>
        rw [hn, pow_succ', mul_smul, LinearMap.map_smul_of_tower, nsmul_eq_mul,
          CharP.cast_eq_zero, zero_mul, LinearMap.zero_apply]
  · rw [trace_eq_finrank_mul_minpoly_nextCoeff]
    obtain ⟨g, hg₁, m, hg₂⟩ :=
      (minpoly.irreducible (IsIntegral.isIntegral (R := K) x)).hasSeparableContraction p
    cases m with
    | zero =>
      obtain rfl : g = minpoly K x := by simpa using hg₂
      cases hx hg₁
    | succ n =>
      rw [nextCoeff, if_neg, ← hg₂, coeff_expand (by positivity),
        if_neg, neg_zero, mul_zero, LinearMap.zero_apply]
      · rw [natDegree_expand]
        intro h
        have := Nat.dvd_sub (dvd_mul_left (p ^ (n + 1)) g.natDegree) h
        rw [tsub_tsub_cancel_of_le, Nat.dvd_one] at this
        · obtain rfl : g = minpoly K x := by simpa [this] using hg₂
          cases hx hg₁
        · rw [Nat.one_le_iff_ne_zero]
          have : g.natDegree ≠ 0 := fun e ↦ by
            have := congr(natDegree $hg₂)
            rw [natDegree_expand, e, zero_mul] at this
            exact (minpoly.natDegree_pos (IsIntegral.isIntegral x)).ne this
          positivity
      · exact (minpoly.natDegree_pos (IsIntegral.isIntegral x)).ne'

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

Goal state before:
pp: case e_f.e_f
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 x y : κ
⊢ ((traceForm A B) (b y * P.map (⇑(algebraMap A B)) y α)) (b x * P.map (⇑(algebraMap A B)) x β) =
    Pᵀ α y * traceMatrix A b y x * P x β

Tactic:
map_apply,

Goal state after:
case e_f.e_f
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 x y : κ
⊢ ((traceForm A B) (b y * (algebraMap A B) (P y α))) (b x * P.map (⇑(algebraMap A B)) x β) =
    Pᵀ α y * traceMatrix A b y x * P x β
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✝¹ : Algebra (FractionRing ↥A) (FractionRing B) := FractionRing.liftAlgebra (↥A) (FractionRing B)
this✝ : MulSemiringAction G (FractionRing B) := IsFractionRing.mulSemiringAction G B (FractionRing B)
this : Algebra R ↥A := (algebraMap R B).rangeRestrict.toAlgebra
⊢ Finite G

Tactic:
have : IsScalarTower R A B := IsScalarTower.of_algebraMap_eq' rfl

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✝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