-- 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 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
this : ‖↑q - x‖ ≤ q + 1
⊢ ‖↑q - x‖ ≤ ↑(q + 1).toNNReal

Tactic:
simp [this]

Result:
no goals

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
this : ¬eval (↑q) (cyclotomic n ℂ) = 0
ζ : ℂ
hζ : ζ ∈ primitiveRoots n ℂ
hhζ : ‖↑q - ζ‖ < q + 1
⊢ True ∧ ‖↑q - ζ‖ < ↑(q + 1).toNNReal

Tactic:
simp [hhζ]

Result:
no goals

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 (-1) n
h : ζ.re ≤ 0 ∧ ζ.im = 0
hζ₀ : ζ ≠ 0
this : ζ = -1
⊢ False

Tactic:
linarith [hζ.unique <| IsPrimitiveRoot.neg_one 0 two_ne_zero.symm]

Result:
no goals

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
⊢ eval q (cyclotomic n ℝ) < (q + 1) ^ φ n

Tactic:
let ζ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)

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
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
⊢ eval q (cyclotomic n ℝ) < (q + 1) ^ φ n

Proof state:
case h.e'_4
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
⊢ Units.mk0 (q + 1).toNNReal ⋯ ^ φ n = ∏ i ∈ (primitiveRoots n ℂ).attach, ?convert_3 i

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

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‖₊ ⋯ ≤ ?convert_3 i

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‖₊ ⋯ < ?convert_3 i

Tactic:
swap

Result:
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

case h.e'_4
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
⊢ Units.mk0 (q + 1).toNNReal ⋯ ^ φ n = ∏ i ∈ (primitiveRoots n ℂ).attach, ?convert_3 i

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‖₊ ⋯ ≤ ?convert_3 i

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‖₊ ⋯ < ?convert_3 i

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
⊢ ζ ≠ 0

Tactic:
clear_value ζ

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
ζ : ℂ
hζ : IsPrimitiveRoot ζ n
h : ζ.re ≤ 0 ∧ ζ.im = 0
⊢ ζ ≠ 0

Proof state:
case h.e'_4.h.e'_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
this : ¬SameRay ℝ (↑q) (-ζ)
⊢ 1 = ‖-ζ‖

Tactic:
simp [abs_of_pos hq, hζ.norm'_eq_one hn.ne']

Result:
no goals

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).arg = 0
⊢ False

Tactic:
rw [Complex.arg_eq_zero_iff, Complex.neg_re, neg_nonneg, Complex.neg_im, neg_eq_zero] at h

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
ζ : ℂ := Complex.exp (2 * ↑Real.pi * Complex.I / ↑n)
hζ : IsPrimitiveRoot ζ n
h : ζ.re ≤ 0 ∧ ζ.im = 0
⊢ 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
hex : ∃ ζ' ∈ primitiveRoots n ℂ, ‖↑q - ζ'‖ < q + 1
this : ¬eval (↑q) (cyclotomic n ℂ) = 0
⊢ Units.mk0 ‖eval (↑q) (cyclotomic n ℂ)‖₊ ⋯ < Units.mk0 (q + 1).toNNReal ⋯ ^ φ n

Tactic:
simp only [cyclotomic_eq_prod_X_sub_primitiveRoots hζ, eval_prod, eval_C, eval_X, eval_sub,
  nnnorm_prod, Units.mk0_prod]

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
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 ⋯ ^ φ n