mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.Geometry.Manifold.Riemannian.Basic

Goal state before:
pp: case hxs
E : Type u_1
inst✝⁷ : NormedAddCommGroup E
inst✝⁶ : NormedSpace ℝ E
H : Type u_2
inst✝⁵ : TopologicalSpace H
I : ModelWithCorners ℝ E H
M : Type u_3
inst✝⁴ : TopologicalSpace M
inst✝³ : ChartedSpace H M
inst✝² : RiemannianBundle fun x ↦ TangentSpace I x
inst✝¹ : IsManifold I 1 M
inst✝ : IsContinuousRiemannianBundle E fun x ↦ TangentSpace I x
x : M
C : ℝ≥0
C_pos : C > 0
hC : ∀ᶠ (y : E) in 𝓝[range ↑I] ↑(extChartAt I x) x, ‖mfderiv[range ↑I] ↑(extChartAt I x).symm y‖ₑ < ↑C
r : ℝ
r_pos : r > 0
hr :
  ball (↑(extChartAt I x) x) r ∩ range ↑I ⊆
    (extChartAt I x).target ∩ {y | ‖mfderiv[range ↑I] ↑(extChartAt I x).symm y‖ₑ < ↑C}
A : ↑(extChartAt I x) ⁻¹' (ball (↑(extChartAt I x) x) r ∩ range ↑I) ∈ 𝓝 x
y : M
hy : y ∈ ↑(extChartAt I x) ⁻¹' (ball (↑(extChartAt I x) x) r ∩ range ↑I)
h'y : y ∈ (chartAt H x).source
η : ℝ →ᴬ[ℝ] E := ⋯
γ : ℝ → M := ⋯
hη :
  Icc 0 1 ⊆ ⇑η ⁻¹' (extChartAt I x).target ∧ Icc 0 1 ⊆ ⇑η ⁻¹' {y | ‖mfderiv[range ↑I] ↑(extChartAt I x).symm y‖ₑ < ↑C}
η_smooth : ContMDiffOn 𝓘(ℝ, ℝ) 𝓘(ℝ, E) 1 (⇑η) (Icc 0 1)
this : riemannianEDist I x y ≤ pathELength I γ 0 1
t : ℝ
ht : t ∈ Icc 0 1
⊢ UniqueMDiffAt[Icc 0 1] t

Tactic:
rw [uniqueMDiffWithinAt_iff_uniqueDiffWithinAt]
      exact uniqueDiffOn_Icc zero_lt_one t ht

Goal state after:
Module: Mathlib.Geometry.Manifold.VectorBundle.Tensoriality

Goal state before:
pp: 𝕜 : Type u_1
inst✝¹⁴ : NontriviallyNormedField 𝕜
E : Type u_2
inst✝¹³ : NormedAddCommGroup E
inst✝¹² : NormedSpace 𝕜 E
H : Type u_3
inst✝¹¹ : TopologicalSpace H
I : ModelWithCorners 𝕜 E H
M : Type u_4
inst✝¹⁰ : TopologicalSpace M
inst✝⁹ : ChartedSpace H M
F : Type u_5
inst✝⁸ : NormedAddCommGroup F
inst✝⁷ : NormedSpace 𝕜 F
V : M → Type u_6
inst✝⁶ : TopologicalSpace (TotalSpace F V)
inst✝⁵ : (x : M) → AddCommGroup (V x)
inst✝⁴ : (x : M) → Module 𝕜 (V x)
inst✝³ : (x : M) → TopologicalSpace (V x)
inst✝² : FiberBundle F V
A : Type u_9
inst✝¹ : AddCommGroup A
inst✝ : Module 𝕜 A
Φ : ((x : M) → V x) → A
x : M
hΦ : TensorialAt I F Φ x
σ σ' : (x : M) → V x
hσ : MDiffAt (T% σ) x
hσ' : MDiffAt (T% σ') x
hσσ' : ∀ᶠ (x' : M) in 𝓝 x, σ x' = σ' x'
ψ : M → 𝕜 := fun x' ↦ if σ x' = σ' x' then 1 else 0
⊢ ψ x = 1

Tactic:
simp [ψ, hσσ'.self_of_nhds]

Goal state after:
Module: Mathlib.Geometry.Manifold.VectorBundle.CovariantDerivative.Torsion

Goal state before:
pp: 𝕜 : Type u_1
inst✝⁷ : NontriviallyNormedField 𝕜
E : Type u_2
inst✝⁶ : NormedAddCommGroup E
inst✝⁵ : NormedSpace 𝕜 E
H : Type u_3
inst✝⁴ : TopologicalSpace H
I : ModelWithCorners 𝕜 E H
M : Type u_4
inst✝³ : TopologicalSpace M
inst✝² : ChartedSpace H M
inst✝¹ : IsManifold I 2 M
inst✝ : CompleteSpace E
cov : ((x : M) → TangentSpace I x) → (x : M) → TangentSpace I x →L[𝕜] TangentSpace I x
hcov : IsCovariantDerivativeOn E cov
x : M
X σ✝ σ'✝ : (x : M) → TangentSpace I x
hY : MDiffAt (T% σ✝) x
hY' : MDiffAt (T% σ'✝) x
⊢ torsionAux cov X (σ✝ + σ'✝) x = torsionAux cov X σ✝ x + torsionAux cov X σ'✝ x

Tactic:
by
    simp [torsionAux, hcov.add hY hY', VectorField.mlieBracket_add_right hY hY']
    module

Goal state after:
Module: Mathlib.GroupTheory.SpecificGroups.Dihedral

Goal state before:
pp: n : ℕ
h1 : n ≠ 1
h : IsCyclic (DihedralGroup n)
⊢ False

Tactic:
by_cases h2 : n = 2
  · simpa [exponent, card, h2] using h.exponent_eq_card
  · exact not_commutative h1 h2 h.isMulCommutative

Goal state after:
Module: Mathlib.GroupTheory.SpecificGroups.Dihedral

Goal state before:
pp: n : ℕ
hn : Odd n
u : (ZMod n)ˣ := ZMod.unitOfCoprime 2 ⋯
hu : ∀ (a : ZMod n), a + a = 0 ↔ a = 0
i j : ZMod n
h✝ : Commute (sr i, sr j).1 (sr i, sr j).2
h : i = j
⊢ ↑u⁻¹ * (j + j) = j ∧ ↑u⁻¹ * (j + j) = j

Tactic:
and_self,

Goal state after:
n : ℕ
hn : Odd n
u : (ZMod n)ˣ := ZMod.unitOfCoprime 2 ⋯
hu : ∀ (a : ZMod n), a + a = 0 ↔ a = 0
i j : ZMod n
h✝ : Commute (sr i, sr j).1 (sr i, sr j).2
h : i = j
⊢ ↑u⁻¹ * (j + j) = j
Module: Mathlib.GroupTheory.SpecificGroups.Dihedral

Goal state before:
pp: case sr
n : ℕ
hodd : Odd n
hne1 : n ≠ 1
i : ZMod n
h : ∀ (g : DihedralGroup n), g * sr i = sr i * g
⊢ sr i = 1

Tactic:
have heq := sr.inj (h (r 1))
    have : Fact (1 < n) := ⟨by grind⟩
    simp [sub_eq_iff_eq_add, add_assoc, ZMod.add_self_eq_zero_iff_eq_zero hodd] at heq

Goal state after:
Module: Mathlib.GroupTheory.Coprod.Basic

Goal state before:
pp: M : Type u_1
N : Type u_2
inst✝¹ : Monoid M
inst✝ : Monoid N
⊢ fst.prod snd = toProd

Tactic:
by ext1 <;> rfl

Goal state after:
Module: Mathlib.GroupTheory.Coprod.Basic

Goal state before:
pp: G : Type u_1
H : Type u_2
inst✝¹ : Group G
inst✝ : Group H
⊢ inl.range ⊔ inr.range = Subgroup.closure (Set.range ⇑inl) ⊔ Subgroup.closure (Set.range ⇑inr)

Tactic:
← MonoidHom.coe_range,

Goal state after:
G : Type u_1
H : Type u_2
inst✝¹ : Group G
inst✝ : Group H
⊢ inl.range ⊔ inr.range = Subgroup.closure ↑inl.range ⊔ Subgroup.closure (Set.range ⇑inr)
Module: Mathlib.GroupTheory.Coprod.Basic

Goal state before:
pp: G : Type u_1
H : Type u_2
inst✝¹ : Group G
inst✝ : Group H
⊢ inl.range ⊔ inr.range = Subgroup.closure ↑inl.range ⊔ Subgroup.closure (Set.range ⇑inr)

Tactic:
← MonoidHom.coe_range,

Goal state after:
G : Type u_1
H : Type u_2
inst✝¹ : Group G
inst✝ : Group H
⊢ inl.range ⊔ inr.range = Subgroup.closure ↑inl.range ⊔ Subgroup.closure ↑inr.range
Module: Mathlib.GroupTheory.Coxeter.Basic

Goal state before:
pp: B : Type u_1
W : Type u_3
inst✝ : Group W
M : CoxeterMatrix B
cs : CoxeterSystem M W
i i' : B
m : ℕ
hm : m ≤ M.M i i' * 2
⊢ cs.wordProd (alternatingWord i i' m) = cs.wordProd (alternatingWord i' i (M.M i i' * 2 - m))

Tactic:
prod_alternatingWord_eq_mul_pow,

Goal state after:
B : Type u_1
W : Type u_3
inst✝ : Group W
M : CoxeterMatrix B
cs : CoxeterSystem M W
i i' : B
m : ℕ
hm : m ≤ M.M i i' * 2
⊢ (if Even m then 1 else cs.simple i') * (cs.simple i * cs.simple i') ^ (m / 2) =
    (if Even (M.M i i' * 2 - m) then 1 else cs.simple i) * (cs.simple i' * cs.simple i) ^ ((M.M i i' * 2 - m) / 2)
Module: Mathlib.GroupTheory.Coxeter.Length

Goal state before:
pp: B : Type u_1
W : Type u_2
inst✝ : Group W
M : CoxeterMatrix B
cs : CoxeterSystem M W
⊢ M.IsLiftable fun x ↦ Multiplicative.ofAdd 1

Tactic:
simp_rw [CoxeterMatrix.IsLiftable, ← ofAdd_add, (by decide : (1 + 1 : ZMod 2) = 0)]
  simp

Goal state after:
Module: Mathlib.GroupTheory.Coxeter.Length

Goal state before:
pp: B : Type u_1
W : Type u_2
inst✝ : Group W
M : CoxeterMatrix B
cs : CoxeterSystem M W
ω : List B
hω : cs.IsReduced ω
⊢ (replicate ω.length (Multiplicative.ofAdd 1)).prod = Multiplicative.ofAdd ↑ω.length

Tactic:
prod_replicate,

Goal state after:
B : Type u_1
W : Type u_2
inst✝ : Group W
M : CoxeterMatrix B
cs : CoxeterSystem M W
ω : List B
hω : cs.IsReduced ω
⊢ Multiplicative.ofAdd 1 ^ ω.length = Multiplicative.ofAdd ↑ω.length
Module: Mathlib.GroupTheory.Coxeter.Inversion

Goal state before:
pp: B : Type u_1
W : Type u_2
inst✝ : Group W
M : CoxeterMatrix B
cs : CoxeterSystem M W
i : B
⊢ cs.rightInvSeq [i] = [cs.simple i]

Tactic:
simp [rightInvSeq]

Goal state after:
Module: Mathlib.GroupTheory.DivisibleHull

Goal state before:
pp: M : Type u_2
inst✝ : AddCommGroup M
a : ℚ
h : 0 ≤ a
x : DivisibleHull M
⊢ a • x =
    (have this := ⟨a, h⟩;
      this) •
      x

Tactic:
by
  have := h.eq_or_lt
  aesop (add simp [qsmul_def, abs_of_pos])

Goal state after:
Module: Mathlib.GroupTheory.Coxeter.Inversion

Goal state before:
pp: case succ
B : Type u_1
W : Type u_2
inst✝ : Group W
M : CoxeterMatrix B
cs : CoxeterSystem M W
p k : ℕ
hk :
  ∀ (i j : B) (h : k < 2 * p),
    (cs.leftInvSeq (alternatingWord i j (2 * p)))[k] = cs.wordProd (alternatingWord j i (2 * k + 1))
i j : B
h : k + 1 < 2 * p
⊢ cs.simple i * cs.wordProd (alternatingWord i j (2 * k + 1)) * cs.simple i =
    cs.simple i * cs.wordProd (alternatingWord j i (2 * k + 1 + 1))

Tactic:
alternatingWord_succ j i,

Goal state after:
case succ
B : Type u_1
W : Type u_2
inst✝ : Group W
M : CoxeterMatrix B
cs : CoxeterSystem M W
p k : ℕ
hk :
  ∀ (i j : B) (h : k < 2 * p),
    (cs.leftInvSeq (alternatingWord i j (2 * p)))[k] = cs.wordProd (alternatingWord j i (2 * k + 1))
i j : B
h : k + 1 < 2 * p
⊢ cs.simple i * cs.wordProd (alternatingWord i j (2 * k + 1)) * cs.simple i =
    cs.simple i * cs.wordProd ((alternatingWord i j (2 * k + 1)).concat i)
Module: Mathlib.GroupTheory.DoubleCoset

Goal state before:
pp: G : Type u_1
inst✝ : Group G
H K : Subgroup G
g : G
this : mk H K g = mk H K g ↔ ∃ h ∈ H, ∃ k ∈ K, g = h * Quotient.out (mk H K g) * k
⊢ ∃ h k, h ∈ H ∧ k ∈ K ∧ Quotient.out (mk H K g) = h * g * k

Tactic:
obtain ⟨h, h_h, k, hk, T⟩ := this.1 rfl

Goal state after:
G : Type u_1
inst✝ : Group G
H K : Subgroup G
g : G
this : mk H K g = mk H K g ↔ ∃ h ∈ H, ∃ k ∈ K, g = h * Quotient.out (mk H K g) * k
h : G
h_h : h ∈ H
k : G
hk : k ∈ K
T : g = h * Quotient.out (mk H K g) * k
⊢ ∃ h k, h ∈ H ∧ k ∈ K ∧ Quotient.out (mk H K g) = h * g * k
Module: Mathlib.GroupTheory.DivisibleHull

Goal state before:
pp: case h₁
M✝ : Type u_1
inst✝³ : AddCommMonoid M✝
M : Type u_2
inst✝² : AddCommGroup M
inst✝¹ : LinearOrder M
inst✝ : IsOrderedAddMonoid M
⊢ (archimedeanClassOrderHom M).comp (archimedeanClassOrderHomInv M) = OrderHom.id

Tactic:
ext a
    induction a with | mk a
    induction a with | mk m s
    suffices ArchimedeanClass.mk (mk m 1) = ArchimedeanClass.mk (mk m s) by
      simpa [archimedeanClassOrderHom, archimedeanClassOrderHomInv]
    simp_rw [aux_archimedeanClassMk_mk]

Goal state after:
Module: Mathlib.GroupTheory.Focal

Goal state before:
pp: case mem
G : Type u_1
inst✝ : Group G
H : Subgroup G
n g : G
hg : g ∈ H
x : G
hxP : x ∈ H
u : G
hzH : ⁅x, u⁆ ∈ H
⊢ g * ⁅x, u⁆ * g⁻¹ ∈ H.focalSubgroup

Tactic:
exact subset_closure ⟨by aesop, g * x * g⁻¹, by aesop, g * u * g⁻¹, by group⟩

Goal state after:
Module: Mathlib.GroupTheory.Focal

Goal state before:
pp: G : Type u_1
inst✝ : Group G
H : Subgroup G
h : G
hh : h ∈ H
g : G
hconj : g⁻¹ * h * g ∈ H
⊢ ↑(⟨g⁻¹ * h * g, hconj⟩⁻¹ * ⟨h, hh⟩) ∈ {g | g ∈ H ∧ ∃ x ∈ H, ∃ u, g = ⁅x, u⁆}

Tactic:
simp only [coe_mul, coe_inv]

Goal state after:
G : Type u_1
inst✝ : Group G
H : Subgroup G
h : G
hh : h ∈ H
g : G
hconj : g⁻¹ * h * g ∈ H
⊢ (g⁻¹ * h * g)⁻¹ * h ∈ {g | g ∈ H ∧ ∃ x ∈ H, ∃ u, g = ⁅x, u⁆}
Module: Mathlib.GroupTheory.Transfer

Goal state before:
pp: case neg.inl
G : Type u_3
inst✝¹ : Group G
inst✝ : Finite G
P : Sylow (Nat.card G).minFac G
hP : IsCyclic ↥↑P
hn : ¬Nat.card G = 1
this : Fact (Nat.Prime (Nat.card G).minFac)
key : (centralizer ↑↑P).relIndex (normalizer ↑↑P) ∣ Nat.card (MulAut ↥↑P)
k : ℕ
hk : Nat.card ↥↑P = (Nat.card G).minFac ^ k
h0 : k = 0
⊢ ((centralizer ↑P).relIndex (normalizer ↑P)).Coprime (Nat.card (MulAut ↥↑P))

Tactic:
rw [hP.card_mulAut, hk, h0, pow_zero, Nat.totient_one]
    apply Nat.coprime_one_right

Goal state after:
Module: Mathlib.GroupTheory.Focal

Goal state before:
pp: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
inst✝ : H.FiniteIndex
x : ↥H
⊢ H.transferFocal ↑x = ↑x ^ H.index

Tactic:
by
  have : Fintype (Quotient (MulAction.orbitRel (zpowers (x : G)) (G ⧸ H))) :=
    Fintype.ofFinite _
  rw [transferFocal, index_eq_sum_minimalPeriod H x, ← Finset.prod_pow_eq_pow_sum,
    MonoidHom.transfer_eq_prod_quotient_orbitRel_zpowers_quot]
  apply Finset.prod_congr rfl
  intros
  apply focalSubgroupOf.mk'_conj_eq H

Goal state after:
Module: Mathlib.GroupTheory.Frattini

Goal state before:
pp: G : Type u_1
H : Type u_2
inst✝¹ : Group G
inst✝ : Group H
φ : G →* H
hφ : Function.Surjective ⇑φ
⊢ Order.radical (Subgroup G) ≤ comap φ (Order.radical (Subgroup H))

Tactic:
Order.radical,

Goal state after:
G : Type u_1
H : Type u_2
inst✝¹ : Group G
inst✝ : Group H
φ : G →* H
hφ : Function.Surjective ⇑φ
⊢ ⨅ a ∈ {H | IsCoatom H}, a ≤ comap φ (⨅ a ∈ {H_1 | IsCoatom H_1}, a)
Module: Mathlib.GroupTheory.FreeGroup.NielsenSchreier

Goal state before:
pp: case inl
G : Type u
inst✝² : Groupoid G
inst✝¹ : IsFreeGroupoid G
T : WideSubquiver (Symmetrify (Generators G))
inst✝ : Arborescence (WideSubquiver.toType (Symmetrify (Generators G)) T)
a b : Generators G
e : a ⟶ b
H : Sum.inl e ∈ T a b
⊢ treeHom T
        (have this := a;
        this) ≫
      of e =
    homOfPath T (default.cons ⟨Sum.inl e, H⟩)

Tactic:
homOfPath

Goal state after:
case inl
G : Type u
inst✝² : Groupoid G
inst✝¹ : IsFreeGroupoid G
T : WideSubquiver (Symmetrify (Generators G))
inst✝ : Arborescence (WideSubquiver.toType (Symmetrify (Generators G)) T)
a b : Generators G
e : a ⟶ b
H : Sum.inl e ∈ T a b
⊢ treeHom T
        (have this := a;
        this) ≫
      of e =
    homOfPath T default ≫ Sum.recOn (↑⟨Sum.inl e, H⟩) (fun e ↦ of e) fun e ↦ inv (of e)
Module: Mathlib.GroupTheory.FreeGroup.NielsenSchreier

Goal state before:
pp: case inr
G : Type u
inst✝² : Groupoid G
inst✝¹ : IsFreeGroupoid G
T : WideSubquiver (Symmetrify (Generators G))
inst✝ : Arborescence (WideSubquiver.toType (Symmetrify (Generators G)) T)
a b : Generators G
e : a ⟶ b
H : Sum.inr e ∈ T b a
⊢ homOfPath T (default.cons ⟨Sum.inr e, H⟩) ≫ of e = treeHom T b

Tactic:
homOfPath

Goal state after:
case inr
G : Type u
inst✝² : Groupoid G
inst✝¹ : IsFreeGroupoid G
T : WideSubquiver (Symmetrify (Generators G))
inst✝ : Arborescence (WideSubquiver.toType (Symmetrify (Generators G)) T)
a b : Generators G
e : a ⟶ b
H : Sum.inr e ∈ T b a
⊢ (homOfPath T default ≫ Sum.recOn (↑⟨Sum.inr e, H⟩) (fun e ↦ of e) fun e ↦ inv (of e)) ≫ of e = treeHom T b
Module: Mathlib.GroupTheory.Nilpotent

Goal state before:
pp: case pos.succ.a
G : Type u_1
inst✝ : Group G
hH : IsNilpotent G
n : ℕ
hn : nilpotencyClass G = n + 1
⊢ upperCentralSeries (G ⧸ center G) n = ⊤

Tactic:
apply comap_injective (f := (mk' (center G))) Quot.mk_surjective

Goal state after:
case pos.succ.a
G : Type u_1
inst✝ : Group G
hH : IsNilpotent G
n : ℕ
hn : nilpotencyClass G = n + 1
⊢ comap (mk' (center G)) (upperCentralSeries (G ⧸ center G) n) = comap (mk' (center G)) ⊤
Module: Mathlib.GroupTheory.GroupAction.Blocks

Goal state before:
pp: case inr.«1»
G : Type u_1
inst✝² : Group G
X : Type u_2
inst✝¹ : MulAction G X
inst✝ : IsPretransitive G X
B : Set X
hX : Finite X
hB : IsBlock G B
hB_ne : B.Nonempty
hB' : 1 < 2
key : B.ncard * 1 = Nat.card X
⊢ B = Set.univ

Tactic:
rw [mul_one, ← Set.ncard_univ] at key
    rw [Set.eq_of_subset_of_ncard_le (Set.subset_univ B) key.ge]

Goal state after:
Module: Mathlib.GroupTheory.SpecificGroups.Alternating

Goal state before:
pp: α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
h3 : 3 ≤ Nat.card α
⊢ Nontrivial ↥(alternatingGroup α)

Tactic:
by
  have : Nontrivial α := by
    rw [← Fintype.one_lt_card_iff_nontrivial, ← Nat.card_eq_fintype_card]
    refine lt_of_lt_of_le (by decide) h3
  rw [← Fintype.one_lt_card_iff_nontrivial, ← Nat.card_eq_fintype_card]
  refine lt_of_mul_lt_mul_left ?_ (le_of_lt Nat.prime_two.pos)
  rw [two_mul_nat_card_alternatingGroup, Nat.card_perm, ← Nat.succ_le_iff]
  exact le_trans h3 (Nat.card α).self_le_factorial

Goal state after:
Module: Mathlib.GroupTheory.SpecificGroups.Alternating

Goal state before:
pp: α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
s : Finset α
⊢ Function.Injective ⇑(ofSubtype s)

Tactic:
rw [← Function.Injective.of_comp_iff (alternatingGroup α).subtype_injective]

Goal state after:
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
s : Finset α
⊢ Function.Injective (⇑(alternatingGroup α).subtype ∘ ⇑(ofSubtype s))
Module: Mathlib.GroupTheory.GroupAction.MultiplePrimitivity

Goal state before:
pp: case inl
M : Type u_1
α : Type u_2
inst✝³ : Group M
inst✝² : MulAction M α
inst✝¹ : IsPretransitive M α
n : ℕ
a : α
inst✝ : IsMultiplyPreprimitive M α n.succ
h0 : n < 1
⊢ IsMultiplyPreprimitive (↥(stabilizer M a)) (↥(ofStabilizer M a)) n

Tactic:
rw [Nat.lt_one_iff] at h0
    rw [h0]
    apply is_zero_preprimitive

Goal state after:
Module: Mathlib.GroupTheory.GroupAction.MultiplePrimitivity

Goal state before:
pp: M : Type u_1
α : Type u_2
inst✝³ : Group M
inst✝² : MulAction M α
m n : ℕ
inst✝¹ : IsMultiplyPreprimitive M α n
s : Set α
inst✝ : Finite ↑s
hs : s.ncard + m = n
t : Set ↥(ofFixingSubgroup M s)
ht : t.encard + 1 = ↑m
t' : Set α := Subtype.val '' t
htt' : t = Subtype.val ⁻¹' t'
⊢ IsPreprimitive ↥(fixingSubgroup (↥(fixingSubgroup M s)) (Subtype.val ⁻¹' t'))
    ↥(ofFixingSubgroup (↥(fixingSubgroup M s)) (Subtype.val ⁻¹' t'))

Tactic:
suffices IsPreprimitive (fixingSubgroup M (s ∪ t')) (ofFixingSubgroup M (s ∪ t')) by
      apply IsPreprimitive.of_surjective map_ofFixingSubgroupUnion_bijective.surjective

Goal state after:
M : Type u_1
α : Type u_2
inst✝³ : Group M
inst✝² : MulAction M α
m n : ℕ
inst✝¹ : IsMultiplyPreprimitive M α n
s : Set α
inst✝ : Finite ↑s
hs : s.ncard + m = n
t : Set ↥(ofFixingSubgroup M s)
ht : t.encard + 1 = ↑m
t' : Set α := Subtype.val '' t
htt' : t = Subtype.val ⁻¹' t'
⊢ IsPreprimitive ↥(fixingSubgroup M (s ∪ t')) ↥(ofFixingSubgroup M (s ∪ t'))
Module: Mathlib.GroupTheory.GroupAction.MultipleTransitivity

Goal state before:
pp: case inl
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
h2 : Nat.card α < 2
⊢ IsMultiplyPretransitive (↥(alternatingGroup α)) α (Nat.card α - 2)

pp: case inr
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
h2 : 2 ≤ Nat.card α
⊢ IsMultiplyPretransitive (↥(alternatingGroup α)) α (Nat.card α - 2)

Tactic:
· rw [Nat.sub_eq_zero_of_le (le_of_lt h2)]
    apply is_zero_pretransitive

Goal state after:
case inr
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
h2 : 2 ≤ Nat.card α
⊢ IsMultiplyPretransitive (↥(alternatingGroup α)) α (Nat.card α - 2)
Module: Mathlib.GroupTheory.SpecificGroups.Alternating.MaximalSubgroups

Goal state before:
pp: α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
s : Set α
hs : sᶜ.Nontrivial
this : ∃ k, k.IsSwap ∧ _root_.Disjoint s ↑k.support
⊢ Function.Surjective toPerm

Tactic:
obtain ⟨k, hk_swap, hk_support⟩ := this

Goal state after:
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
s : Set α
hs : sᶜ.Nontrivial
k : Perm α
hk_swap : k.IsSwap
hk_support : _root_.Disjoint s ↑k.support
⊢ Function.Surjective toPerm
Module: Mathlib.GroupTheory.GroupAction.Jordan

Goal state before:
pp: n : ℕ
hrec :
  ∀ m < n,
    ∀ {G : Type u_1} {α : Type u_2} [inst : Group G] [inst_1 : MulAction G α],
      IsPreprimitive G α →
        ∀ {s : Set α},
          s.ncard = m + 1 →
            m + 2 < Nat.card α →
              (IsPretransitive ↥(fixingSubgroup G s) ↥(ofFixingSubgroup G s) → IsMultiplyPretransitive G α 2) ∧
                (IsPreprimitive ↥(fixingSubgroup G s) ↥(ofFixingSubgroup G s) → IsMultiplyPreprimitive G α 2)
G : Type u_1
α : Type u_2
inst✝¹ : Group G
inst✝ : MulAction G α
hG : IsPreprimitive G α
s : Set α
hsn : s.ncard = n + 1
hsn' : n + 2 < Nat.card α
this : Finite α
hs_ne_univ : s ≠ Set.univ
hs_nonempty : s.Nonempty
hn : n + 1 ≥ 2
hn2 : 2 * (n + 1) ≥ Nat.card α
a : α
ha✝ : a ∈ sᶜ
b : α
hb : b ∈ sᶜ
hab : a ≠ b
g : G
hga : a ∈ g • sᶜ
hgb : b ∉ g • sᶜ
t : Set α := s ∩ g • s
ha : a ∉ s ∪ g • s
htm : t.ncard = t.ncard - 1 + 1
h : s ⊆ t
⊢ s = g • s

Tactic:
apply Set.eq_of_subset_of_ncard_le _ _ (g • s).toFinite

Goal state after:
n : ℕ
hrec :
  ∀ m < n,
    ∀ {G : Type u_1} {α : Type u_2} [inst : Group G] [inst_1 : MulAction G α],
      IsPreprimitive G α →
        ∀ {s : Set α},
          s.ncard = m + 1 →
            m + 2 < Nat.card α →
              (IsPretransitive ↥(fixingSubgroup G s) ↥(ofFixingSubgroup G s) → IsMultiplyPretransitive G α 2) ∧
                (IsPreprimitive ↥(fixingSubgroup G s) ↥(ofFixingSubgroup G s) → IsMultiplyPreprimitive G α 2)
G : Type u_1
α : Type u_2
inst✝¹ : Group G
inst✝ : MulAction G α
hG : IsPreprimitive G α
s : Set α
hsn : s.ncard = n + 1
hsn' : n + 2 < Nat.card α
this : Finite α
hs_ne_univ : s ≠ Set.univ
hs_nonempty : s.Nonempty
hn : n + 1 ≥ 2
hn2 : 2 * (n + 1) ≥ Nat.card α
a : α
ha✝ : a ∈ sᶜ
b : α
hb : b ∈ sᶜ
hab : a ≠ b
g : G
hga : a ∈ g • sᶜ
hgb : b ∉ g • sᶜ
t : Set α := ⋯
ha : a ∉ s ∪ g • s
htm : t.ncard = t.ncard - 1 + 1
h : s ⊆ t
⊢ s ⊆ g • s

n : ℕ
hrec :
  ∀ m < n,
    ∀ {G : Type u_1} {α : Type u_2} [inst : Group G] [inst_1 : MulAction G α],
      IsPreprimitive G α →
        ∀ {s : Set α},
          s.ncard = m + 1 →
            m + 2 < Nat.card α →
              (IsPretransitive ↥(fixingSubgroup G s) ↥(ofFixingSubgroup G s) → IsMultiplyPretransitive G α 2) ∧
                (IsPreprimitive ↥(fixingSubgroup G s) ↥(ofFixingSubgroup G s) → IsMultiplyPreprimitive G α 2)
G : Type u_1
α : Type u_2
inst✝¹ : Group G
inst✝ : MulAction G α
hG : IsPreprimitive G α
s : Set α
hsn : s.ncard = n + 1
hsn' : n + 2 < Nat.card α
this : Finite α
hs_ne_univ : s ≠ Set.univ
hs_nonempty : s.Nonempty
hn : n + 1 ≥ 2
hn2 : 2 * (n + 1) ≥ Nat.card α
a : α
ha✝ : a ∈ sᶜ
b : α
hb : b ∈ sᶜ
hab : a ≠ b
g : G
hga : a ∈ g • sᶜ
hgb : b ∉ g • sᶜ
t : Set α := ⋯
ha : a ∉ s ∪ g • s
htm : t.ncard = t.ncard - 1 + 1
h : s ⊆ t
⊢ (g • s).ncard ≤ s.ncard
Module: Mathlib.GroupTheory.SpecificGroups.Alternating.MaximalSubgroups

Goal state before:
pp: case inr
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
s : Set α
hs : sᶜ.Nontrivial
k : Perm α
hk_swap : k.IsSwap
hk_support : _root_.Disjoint s ↑k.support
hks : k • s = s
g : Perm ↑s
hsg : sign g = -1
⊢ ∃ a, toPerm a = g

Tactic:
use! Equiv.Perm.ofSubtype g * k

Goal state after:
case property
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
s : Set α
hs : sᶜ.Nontrivial
k : Perm α
hk_swap : k.IsSwap
hk_support : _root_.Disjoint s ↑k.support
hks : k • s = s
g : Perm ↑s
hsg : sign g = -1
⊢ Perm.ofSubtype g * k ∈ alternatingGroup α

case property
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
s : Set α
hs : sᶜ.Nontrivial
k : Perm α
hk_swap : k.IsSwap
hk_support : _root_.Disjoint s ↑k.support
hks : k • s = s
g : Perm ↑s
hsg : sign g = -1
⊢ ⟨Perm.ofSubtype g * k, ?property⟩ ∈ stabilizer (↥(alternatingGroup α)) s

case h
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
s : Set α
hs : sᶜ.Nontrivial
k : Perm α
hk_swap : k.IsSwap
hk_support : _root_.Disjoint s ↑k.support
hks : k • s = s
g : Perm ↑s
hsg : sign g = -1
⊢ toPerm ⟨⟨Perm.ofSubtype g * k, ?property⟩, ?property✝⟩ = g
Module: Mathlib.GroupTheory.GroupAction.Jordan

Goal state before:
pp: α : Type u_1
K : Type u_2
inst✝¹ : Group K
inst✝ : MulAction K α
hα : Nat.card α = 2
hK : fixedPoints K α ≠ _root_.Set.univ
n : ℕ
this✝ : Finite α
this : Fintype α
φ : K →* Perm α := ⋯
f : α →ₑ[⇑φ] α := ⋯
hf : Function.Bijective ⇑f
⊢ Nat.card ↥φ.range = Nat.card (Perm α)

Tactic:
apply le_antisymm (card_le_card_group φ.range)

Goal state after:
α : Type u_1
K : Type u_2
inst✝¹ : Group K
inst✝ : MulAction K α
hα : Nat.card α = 2
hK : fixedPoints K α ≠ _root_.Set.univ
n : ℕ
this✝ : Finite α
this : Fintype α
φ : K →* Perm α := ⋯
f : α →ₑ[⇑φ] α := ⋯
hf : Function.Bijective ⇑f
⊢ Nat.card (Perm α) ≤ Nat.card ↥φ.range
Module: Mathlib.GroupTheory.GroupAction.Jordan

Goal state before:
pp: α : Type u_1
G : Subgroup (Perm α)
inst✝¹ : Fintype α
inst✝ : DecidableEq α
g : Perm α
hgc : g.IsCycle
hg : g ∈ G
⊢ IsPretransitive ↥(fixingSubgroup (↥G) (↑g.support)ᶜ) ↥(ofFixingSubgroup (↥G) (↑g.support)ᶜ)

Tactic:
obtain ⟨a, _, hgc⟩ := hgc

Goal state after:
α : Type u_1
G : Subgroup (Perm α)
inst✝¹ : Fintype α
inst✝ : DecidableEq α
g : Perm α
hg : g ∈ G
a : α
left✝ : g a ≠ a
hgc : ∀ ⦃y : α⦄, g y ≠ y → g.SameCycle a y
⊢ IsPretransitive ↥(fixingSubgroup (↥G) (↑g.support)ᶜ) ↥(ofFixingSubgroup (↥G) (↑g.support)ᶜ)
Module: Mathlib.GroupTheory.HNNExtension

Goal state before:
pp: G : Type u_1
inst✝ : Group G
A B : Subgroup G
φ : ↥A ≃* ↥B
a : ↥A
⊢ of ↑a * t⁻¹ = t⁻¹ * of ↑(φ a)

Tactic:
rw [equiv_eq_conj]; simp [mul_assoc]

Goal state after: