-- Mathlib/Algebra/Lie/Solvable.lean
theorem derivedSeries_succ_eq_top_iff (n : ℕ) :
    derivedSeries R L (n + 1) = ⊤ ↔ derivedSeries R L 1 = ⊤

Proof state:
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
⊢ derivedSeries R L (n + 1) = ⊤ ↔ derivedSeries R L 1 = ⊤

Tactic:
simp only [derivedSeries_def]

Result:
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
⊢ derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤

Proof state:
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
ih : derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤
h : derivedSeriesOfIdeal R L 1 ⊤ = ⊤
⊢ ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ = ⊤

Tactic:
rwa [ih.mpr h]

Result:
no goals

Proof state:
case succ
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
ih : derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤
h : ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ = ⊤
⊢ ⊤ ≤ derivedSeriesOfIdeal R L (n + 1) ⊤

Tactic:
conv_lhs => rw [← h]

Result:
case succ
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
ih : derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤
h : ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ = ⊤
⊢ ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ ≤ derivedSeriesOfIdeal R L (n + 1) ⊤

Proof state:
case zero
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
⊢ derivedSeriesOfIdeal R L (0 + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤

Tactic:
simp

Result:
no goals

Proof state:
case succ
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
ih : derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤
h : ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ = ⊤
⊢ ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ ≤ derivedSeriesOfIdeal R L (n + 1) ⊤

Tactic:
exact LieSubmodule.lie_le_right _ _

Result:
no goals

Proof state:
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
⊢ derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤

Tactic:
induction n with
| zero => simp
| succ n ih =>
  rw [derivedSeriesOfIdeal_succ]
  refine ⟨fun h ↦ ?_, fun h ↦ by rwa [ih.mpr h]⟩
  rw [← ih, eq_top_iff]
  conv_lhs => rw [← h]
  exact LieSubmodule.lie_le_right _ _

Result:
no goals

Proof state:
case succ
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
ih : derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤
⊢ ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤

Tactic:
refine ⟨fun h ↦ ?_, fun h ↦ by rwa [ih.mpr h]⟩

Result:
case succ
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
ih : derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤
h : ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ = ⊤
⊢ derivedSeriesOfIdeal R L 1 ⊤ = ⊤

Proof state:
case succ
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
ih : derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤
⊢ derivedSeriesOfIdeal R L (n + 1 + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤

Tactic:
rw [derivedSeriesOfIdeal_succ]

Result:
case succ
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
ih : derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤
⊢ ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤

Proof state:
case succ
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
ih : derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤
h : ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ = ⊤
⊢ derivedSeriesOfIdeal R L 1 ⊤ = ⊤

Tactic:
rw [← ih, eq_top_iff]

Result:
case succ
R : Type u
L : Type v
inst✝² : CommRing R
inst✝¹ : LieRing L
inst✝ : LieAlgebra R L
n : ℕ
ih : derivedSeriesOfIdeal R L (n + 1) ⊤ = ⊤ ↔ derivedSeriesOfIdeal R L 1 ⊤ = ⊤
h : ⁅derivedSeriesOfIdeal R L (n + 1) ⊤, derivedSeriesOfIdeal R L (n + 1) ⊤⁆ = ⊤
⊢ ⊤ ≤ derivedSeriesOfIdeal R L (n + 1) ⊤