-- Mathlib/RingTheory/Polynomial/Cyclotomic/Eval.lean
theorem cyclotomic_eval_lt_add_one_pow_totient {n : ℕ} {q : ℝ} (hn' : 3 ≤ n) (hq' : 1 < q) :
    (cyclotomic n ℝ).eval q < (q + 1) ^ totient n

Proof state:
case h.e'_3
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this✝ : ¬eval (↑q) (cyclotomic n ℂ) = 0
this : ‖eval (↑q) (cyclotomic n ℂ)‖ < ((q + 1) ⊔ 0) ^ φ n
⊢ eval q (cyclotomic n ℝ) = ‖eval (↑q) (cyclotomic n ℂ)‖

Tactic:
rw [eq_comm]

Result:
case h.e'_3
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this✝ : ¬eval (↑q) (cyclotomic n ℂ) = 0
this : ‖eval (↑q) (cyclotomic n ℂ)‖ < ((q + 1) ⊔ 0) ^ φ n
⊢ ‖eval (↑q) (cyclotomic n ℂ)‖ = eval q (cyclotomic n ℝ)

Proof state:
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
⊢ ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1

Tactic:
intro ζ' hζ'

Result:
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
ζ' : ℂ
hζ' : ζ' ∈ primitiveRoots n ℂ
⊢ ‖↑q - ζ'‖ ≤ q + 1

Proof state:
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this : ¬eval (↑q) (cyclotomic n ℂ) = 0
⊢ 0 < q + 1

Tactic:
linarith

Result:
no goals

Proof state:
case h.e'_4.h.e'_5
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
this : ¬SameRay ℝ (↑q) (-ζ)
⊢ q = ‖↑q‖

Tactic:
rw [Complex.norm_real]

Result:
case h.e'_4.h.e'_5
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
this : ¬SameRay ℝ (↑q) (-ζ)
⊢ q = ‖q‖

Proof state:
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
ζ' : ℂ
hζ' : ζ' ∈ primitiveRoots n ℂ
⊢ ‖↑q - ζ'‖ ≤ q + 1

Tactic:
rw [mem_primitiveRoots hn] at hζ'

Result:
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
ζ' : ℂ
hζ' : IsPrimitiveRoot ζ' n
⊢ ‖↑q - ζ'‖ ≤ q + 1

Proof state:
case convert_5
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this : ¬eval (↑q) (cyclotomic n ℂ) = 0
⊢ ∀ a ∈ primitiveRoots n ℂ, ‖↑q - a‖ ≤ ↑(q + 1).toNNReal

Tactic:
intro x hx

Result:
case convert_5
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this : ¬eval (↑q) (cyclotomic n ℂ) = 0
x : ℂ
hx : x ∈ primitiveRoots n ℂ
⊢ ‖↑q - x‖ ≤ ↑(q + 1).toNNReal

Proof state:
case convert_5
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this : ¬eval (↑q) (cyclotomic n ℂ) = 0
⊢ ∀ i ∈ (primitiveRoots n ℂ).attach, Units.mk0 ‖↑q - ↑i‖₊ ⋯ ≤ Units.mk0 (q + 1).toNNReal ⋯

Tactic:
simp only [Subtype.coe_mk, Finset.mem_attach, forall_true_left, Subtype.forall, ←
  Units.val_le_val, ← NNReal.coe_le_coe, norm_nonneg, hq'.le, Units.val_mk0,
  Real.coe_toNNReal, coe_nnnorm, max_le_iff]

Result:
case convert_5
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this : ¬eval (↑q) (cyclotomic n ℂ) = 0
⊢ ∀ a ∈ primitiveRoots n ℂ, ‖↑q - a‖ ≤ ↑(q + 1).toNNReal

Proof state:
case refine_2
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
h : ζ.re ≤ 0 ∧ ζ.im = 0
hζ₀ : ζ ≠ 0
this : ζ.re < 0 ∧ ζ.im = 0
⊢ False

Tactic:
rw [← Complex.arg_eq_pi_iff, hζ.arg_eq_pi_iff hn.ne'] at this

Result:
case refine_2
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
h : ζ.re ≤ 0 ∧ ζ.im = 0
hζ₀ : ζ ≠ 0
this : ζ = -1
⊢ False

Proof state:
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
h : ζ.re ≤ 0 ∧ ζ.im = 0
hζ₀ : ζ ≠ 0
⊢ False

Tactic:
have : ζ.re < 0 ∧ ζ.im = 0 := ⟨h.1.lt_of_ne ?_, h.2⟩

Result:
case refine_2
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
h : ζ.re ≤ 0 ∧ ζ.im = 0
hζ₀ : ζ ≠ 0
this : ζ.re < 0 ∧ ζ.im = 0
⊢ False

case refine_1
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
h : ζ.re ≤ 0 ∧ ζ.im = 0
hζ₀ : ζ ≠ 0
⊢ ζ.re ≠ 0

Proof state:
case convert_3
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this : ¬eval (↑q) (cyclotomic n ℂ) = 0
⊢ { x // x ∈ primitiveRoots n ℂ } → NNRealˣ

Tactic:
exact fun _ => Units.mk0 (Real.toNNReal (q + 1)) (by simp; linarith only [hq'])

Result:
no goals

Proof state:
case h.e'_4.h.e'_5
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this✝ : ¬eval (↑q) (cyclotomic n ℂ) = 0
this : ‖eval (↑q) (cyclotomic n ℂ)‖ < ((q + 1) ⊔ 0) ^ φ n
⊢ 0 ≤ q + 1

Tactic:
linarith

Result:
no goals

Proof state:
case convert_6
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this : ¬eval (↑q) (cyclotomic n ℂ) = 0
⊢ ∃ i ∈ (primitiveRoots n ℂ).attach, Units.mk0 ‖↑q - ↑i‖₊ ⋯ < Units.mk0 (q + 1).toNNReal ⋯

Tactic:
simp only [Subtype.coe_mk, Finset.mem_attach, exists_true_left, Subtype.exists, ←
  NNReal.coe_lt_coe, ← Units.val_lt_val, Units.val_mk0 _, coe_nnnorm]

Result:
case convert_6
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this : ¬eval (↑q) (cyclotomic n ℂ) = 0
⊢ ∃ a, ∃ (_ : a ∈ primitiveRoots n ℂ), True ∧ ‖↑q - a‖ < ↑(q + 1).toNNReal

Proof state:
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
ζ : ℂ
hζ : IsPrimitiveRoot ζ n
h : ζ.re ≤ 0 ∧ ζ.im = 0
⊢ ζ ≠ 0

Tactic:
rintro rfl

Result:
n : ℕ
q : ℝ
hn' : 3 ≤ n
hq' : 1 < q
hn : 0 < n
hq : 0 < q
hfor : ∀ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ ≤ q + 1
hζ : IsPrimitiveRoot 0 n
h : Complex.re 0 ≤ 0 ∧ Complex.im 0 = 0
⊢ False