Theorem: LieAlgebra.IsKilling.rootSpace_neg_nsmul_add_chainTop_of_lt
File: Mathlib/Algebra/Lie/Weights/RootSystem.lean

tactic: by_contra e
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
⊢ rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
state_after: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
⊢ False

tactic: let W : Weight K H L := ⟨_, e⟩
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
⊢ False
state_after: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
⊢ False

tactic: have hW : (W : H → K) = - (n • α) + chainTop α β := rfl
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
⊢ False
state_after: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
⊢ False

tactic: have H₁ : 1 + n + chainTopCoeff (-α) W ≤ chainLength (-α) W := by
  have := apply_coroot_eq_cast' (-α) W
  simp only [coroot_neg, map_neg, hW, nsmul_eq_mul, Pi.natCast_def, coe_chainTop, zsmul_eq_mul,
    Int.cast_natCast, Pi.add_apply, Pi.neg_apply, Pi.mul_apply, root_apply_coroot hα, mul_two,
    neg_add_rev, apply_coroot_eq_cast' α β, Int.cast_sub, Int.cast_mul, Int.cast_ofNat,
    mul_comm (2 : K), add_sub_cancel, neg_neg, add_sub, Nat.cast_inj,
    eq_sub_iff_add_eq, ← Nat.cast_add, ← sub_eq_neg_add, sub_eq_iff_eq_add] at this
  linarith [this, hn]
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
⊢ False
state_after: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
⊢ False

tactic: have H₂ : ((1 + n + chainTopCoeff (-α) W) • α + chainTop (-α) W : H → K) =
    (chainTopCoeff α β + 1) • α + β := by
  simp only [Weight.coe_neg, nsmul_eq_smul_cast ℤ, Nat.cast_add, Nat.cast_one, coe_chainTop,
    smul_neg, ← neg_smul, hW, ← add_assoc, ← add_smul, ← sub_eq_add_neg]
  congr 2
  ring
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
⊢ False
state_after: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
H₂ : (1 + n + chainTopCoeff (⇑(-α)) W) • ⇑α + ⇑(chainTop (⇑(-α)) W) = (chainTopCoeff (⇑α) β + 1) • ⇑α + ⇑β
⊢ False

tactic: have := rootSpace_neg_nsmul_add_chainTop_of_le (-α) W H₁
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
H₂ : (1 + n + chainTopCoeff (⇑(-α)) W) • ⇑α + ⇑(chainTop (⇑(-α)) W) = (chainTopCoeff (⇑α) β + 1) • ⇑α + ⇑β
⊢ False
state_after: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
H₂ : (1 + n + chainTopCoeff (⇑(-α)) W) • ⇑α + ⇑(chainTop (⇑(-α)) W) = (chainTopCoeff (⇑α) β + 1) • ⇑α + ⇑β
this : rootSpace H (-((1 + n + chainTopCoeff (⇑(-α)) W) • ⇑(-α)) + ⇑(chainTop (⇑(-α)) W)) ≠ ⊥
⊢ False

tactic: rw [Weight.coe_neg, ← smul_neg, neg_neg, ← Weight.coe_neg, H₂] at this
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
H₂ : (1 + n + chainTopCoeff (⇑(-α)) W) • ⇑α + ⇑(chainTop (⇑(-α)) W) = (chainTopCoeff (⇑α) β + 1) • ⇑α + ⇑β
this : rootSpace H (-((1 + n + chainTopCoeff (⇑(-α)) W) • ⇑(-α)) + ⇑(chainTop (⇑(-α)) W)) ≠ ⊥
⊢ False
state_after: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
H₂ : (1 + n + chainTopCoeff (⇑(-α)) W) • ⇑α + ⇑(chainTop (⇑(-α)) W) = (chainTopCoeff (⇑α) β + 1) • ⇑α + ⇑β
this : rootSpace H ((chainTopCoeff (⇑α) β + 1) • ⇑α + ⇑β) ≠ ⊥
⊢ False

tactic: exact this (weightSpace_chainTopCoeff_add_one_nsmul_add α β hα)
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
H₂ : (1 + n + chainTopCoeff (⇑(-α)) W) • ⇑α + ⇑(chainTop (⇑(-α)) W) = (chainTopCoeff (⇑α) β + 1) • ⇑α + ⇑β
this : rootSpace H ((chainTopCoeff (⇑α) β + 1) • ⇑α + ⇑β) ≠ ⊥
⊢ False
state_after: no goals

tactic: have := apply_coroot_eq_cast' (-α) W
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
⊢ 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
state_after: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
this : W (coroot (-α)) = ↑(↑(chainLength (-α) W) - 2 * ↑(chainTopCoeff (⇑(-α)) W))
⊢ 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W

tactic: simp only [coroot_neg, map_neg, hW, nsmul_eq_mul, Pi.natCast_def, coe_chainTop, zsmul_eq_mul,
  Int.cast_natCast, Pi.add_apply, Pi.neg_apply, Pi.mul_apply, root_apply_coroot hα, mul_two,
  neg_add_rev, apply_coroot_eq_cast' α β, Int.cast_sub, Int.cast_mul, Int.cast_ofNat,
  mul_comm (2 : K), add_sub_cancel, neg_neg, add_sub, Nat.cast_inj,
  eq_sub_iff_add_eq, ← Nat.cast_add, ← sub_eq_neg_add, sub_eq_iff_eq_add] at this
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
this : W (coroot (-α)) = ↑(↑(chainLength (-α) W) - 2 * ↑(chainTopCoeff (⇑(-α)) W))
⊢ 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
state_after: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
this : chainTopCoeff (⇑(-α)) W + chainTopCoeff (⇑(-α)) W + (n + n) = chainLength (-α) W + chainLength α β
⊢ 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W

tactic: linarith [this, hn]
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
this : chainTopCoeff (⇑(-α)) W + chainTopCoeff (⇑(-α)) W + (n + n) = chainLength (-α) W + chainLength α β
⊢ 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
state_after: no goals

tactic: simp only [Weight.coe_neg, nsmul_eq_smul_cast ℤ, Nat.cast_add, Nat.cast_one, coe_chainTop,
  smul_neg, ← neg_smul, hW, ← add_assoc, ← add_smul, ← sub_eq_add_neg]
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
⊢ (1 + n + chainTopCoeff (⇑(-α)) W) • ⇑α + ⇑(chainTop (⇑(-α)) W) = (chainTopCoeff (⇑α) β + 1) • ⇑α + ⇑β
state_after: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
⊢ (1 + ↑n + ↑(chainTopCoeff (-⇑α) W) + (-↑(chainTopCoeff (-⇑α) W) - ↑n) + ↑(chainTopCoeff (⇑α) β)) • ⇑α + ⇑β =
    (↑(chainTopCoeff (⇑α) β) + 1) • ⇑α + ⇑β

tactic: congr 2
state_before: K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
⊢ (1 + ↑n + ↑(chainTopCoeff (-⇑α) W) + (-↑(chainTopCoeff (-⇑α) W) - ↑n) + ↑(chainTopCoeff (⇑α) β)) • ⇑α + ⇑β =
    (↑(chainTopCoeff (⇑α) β) + 1) • ⇑α + ⇑β
state_after: case e_a.e_a
K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
⊢ 1 + ↑n + ↑(chainTopCoeff (-⇑α) W) + (-↑(chainTopCoeff (-⇑α) W) - ↑n) + ↑(chainTopCoeff (⇑α) β) =
    ↑(chainTopCoeff (⇑α) β) + 1

tactic: ring
state_before: case e_a.e_a
K : Type u_1
L : Type u_2
inst✝⁷ : Field K
inst✝⁶ : CharZero K
inst✝⁵ : LieRing L
inst✝⁴ : LieAlgebra K L
inst✝³ : IsKilling K L
inst✝² : FiniteDimensional K L
H : LieSubalgebra K L
inst✝¹ : H.IsCartanSubalgebra
inst✝ : IsTriangularizable K (↥H) L
α β : Weight K (↥H) L
hα : α.IsNonZero
n : ℕ
hn : chainLength α β < n
e : ¬rootSpace H (-(n • ⇑α) + ⇑(chainTop (⇑α) β)) = ⊥
W : Weight K (↥H) L := { toFun := -(n • ⇑α) + ⇑(chainTop (⇑α) β), weightSpace_ne_bot' := e }
hW : ⇑W = -(n • ⇑α) + ⇑(chainTop (⇑α) β)
H₁ : 1 + n + chainTopCoeff (⇑(-α)) W ≤ chainLength (-α) W
⊢ 1 + ↑n + ↑(chainTopCoeff (-⇑α) W) + (-↑(chainTopCoeff (-⇑α) W) - ↑n) + ↑(chainTopCoeff (⇑α) β) =
    ↑(chainTopCoeff (⇑α) β) + 1
state_after: no goals