Theorem: Equiv.Perm.fin_5_not_solvable
File: Mathlib/GroupTheory/Solvable.lean

Proof steps:
state_before: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
⊢ ¬IsSolvable (Perm (Fin 5))
state_after: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
⊢ ¬IsSolvable (Perm (Fin 5))
tactic: let x : Equiv.Perm (Fin 5) := ⟨![1, 2, 0, 3, 4], ![2, 0, 1, 3, 4], by decide, by decide⟩
state_before: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
⊢ ¬IsSolvable (Perm (Fin 5))
state_after: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
y : Perm (Fin 5) := { toFun := ![3, 4, 2, 0, 1], invFun := ![3, 4, 2, 0, 1], left_inv := ⋯, right_inv := ⋯ }
⊢ ¬IsSolvable (Perm (Fin 5))
tactic: let y : Equiv.Perm (Fin 5) := ⟨![3, 4, 2, 0, 1], ![3, 4, 2, 0, 1], by decide, by decide⟩
state_before: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
y : Perm (Fin 5) := { toFun := ![3, 4, 2, 0, 1], invFun := ![3, 4, 2, 0, 1], left_inv := ⋯, right_inv := ⋯ }
⊢ ¬IsSolvable (Perm (Fin 5))
state_after: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
y : Perm (Fin 5) := { toFun := ![3, 4, 2, 0, 1], invFun := ![3, 4, 2, 0, 1], left_inv := ⋯, right_inv := ⋯ }
z : Perm (Fin 5) := { toFun := ![0, 3, 2, 1, 4], invFun := ![0, 3, 2, 1, 4], left_inv := ⋯, right_inv := ⋯ }
⊢ ¬IsSolvable (Perm (Fin 5))
tactic: let z : Equiv.Perm (Fin 5) := ⟨![0, 3, 2, 1, 4], ![0, 3, 2, 1, 4], by decide, by decide⟩
state_before: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
y : Perm (Fin 5) := { toFun := ![3, 4, 2, 0, 1], invFun := ![3, 4, 2, 0, 1], left_inv := ⋯, right_inv := ⋯ }
z : Perm (Fin 5) := { toFun := ![0, 3, 2, 1, 4], invFun := ![0, 3, 2, 1, 4], left_inv := ⋯, right_inv := ⋯ }
⊢ ¬IsSolvable (Perm (Fin 5))
state_after: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
y : Perm (Fin 5) := { toFun := ![3, 4, 2, 0, 1], invFun := ![3, 4, 2, 0, 1], left_inv := ⋯, right_inv := ⋯ }
z : Perm (Fin 5) := { toFun := ![0, 3, 2, 1, 4], invFun := ![0, 3, 2, 1, 4], left_inv := ⋯, right_inv := ⋯ }
key : x = z * ⁅x, y * x * y⁻¹⁆ * z⁻¹
⊢ ¬IsSolvable (Perm (Fin 5))
tactic: have key : x = z * ⁅x, y * x * y⁻¹⁆ * z⁻¹ := by unfold_let; decide
state_before: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
y : Perm (Fin 5) := { toFun := ![3, 4, 2, 0, 1], invFun := ![3, 4, 2, 0, 1], left_inv := ⋯, right_inv := ⋯ }
z : Perm (Fin 5) := { toFun := ![0, 3, 2, 1, 4], invFun := ![0, 3, 2, 1, 4], left_inv := ⋯, right_inv := ⋯ }
key : x = z * ⁅x, y * x * y⁻¹⁆ * z⁻¹
⊢ ¬IsSolvable (Perm (Fin 5))
state_after: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
y : Perm (Fin 5) := { toFun := ![3, 4, 2, 0, 1], invFun := ![3, 4, 2, 0, 1], left_inv := ⋯, right_inv := ⋯ }
z : Perm (Fin 5) := { toFun := ![0, 3, 2, 1, 4], invFun := ![0, 3, 2, 1, 4], left_inv := ⋯, right_inv := ⋯ }
key : x = z * ⁅x, y * x * y⁻¹⁆ * z⁻¹
n : ℕ
⊢ x ∈ derivedSeries (Perm (Fin 5)) n
tactic: refine not_solvable_of_mem_derivedSeries (show x ≠ 1 by decide) fun n => ?_
state_before: G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
y : Perm (Fin 5) := { toFun := ![3, 4, 2, 0, 1], invFun := ![3, 4, 2, 0, 1], left_inv := ⋯, right_inv := ⋯ }
z : Perm (Fin 5) := { toFun := ![0, 3, 2, 1, 4], invFun := ![0, 3, 2, 1, 4], left_inv := ⋯, right_inv := ⋯ }
key : x = z * ⁅x, y * x * y⁻¹⁆ * z⁻¹
n : ℕ
⊢ x ∈ derivedSeries (Perm (Fin 5)) n
state_after: case zero
G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
y : Perm (Fin 5) := { toFun := ![3, 4, 2, 0, 1], invFun := ![3, 4, 2, 0, 1], left_inv := ⋯, right_inv := ⋯ }
z : Perm (Fin 5) := { toFun := ![0, 3, 2, 1, 4], invFun := ![0, 3, 2, 1, 4], left_inv := ⋯, right_inv := ⋯ }
key : x = z * ⁅x, y * x * y⁻¹⁆ * z⁻¹
⊢ x ∈ derivedSeries (Perm (Fin 5)) 0

case succ
G : Type u_1
G' : Type u_2
inst✝¹ : Group G
inst✝ : Group G'
f : G →* G'
x : Perm (Fin 5) := { toFun := ![1, 2, 0, 3, 4], invFun := ![2, 0, 1, 3, 4], left_inv := ⋯, right_inv := ⋯ }
y : Perm (Fin 5) := { toFun := ![3, 4, 2, 0, 1], invFun := ![3, 4, 2, 0, 1], left_inv := ⋯, right_inv := ⋯ }
z : Perm (Fin 5) := { toFun := ![0, 3, 2, 1, 4], invFun := ![0, 3, 2, 1, 4], left_inv := ⋯, right_inv := ⋯ }
key : x = z * ⁅x, y * x * y⁻¹⁆ * z⁻¹
n : ℕ
ih : x ∈ derivedSeries (Perm (Fin 5)) n
⊢ x ∈ derivedSeries (Perm (Fin 5)) (n + 1)
tactic: induction' n with n ih