Theorem: Polynomial.cyclotomic_pos
File: Mathlib/RingTheory/Polynomial/Cyclotomic/Eval.lean

tactic: induction' n using Nat.strong_induction_on with n ih
state_before: n : ℕ
hn : 2 < n
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
⊢ 0 < eval x (cyclotomic n R)
state_after: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
⊢ 0 < eval x (cyclotomic n R)

tactic: have hn' : 0 < n := pos_of_gt hn
state_before: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
⊢ 0 < eval x (cyclotomic n R)
state_after: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
⊢ 0 < eval x (cyclotomic n R)

tactic: have hn'' : 1 < n := one_lt_two.trans hn
state_before: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
⊢ 0 < eval x (cyclotomic n R)
state_after: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
⊢ 0 < eval x (cyclotomic n R)

tactic: have := prod_cyclotomic_eq_geom_sum hn' R
state_before: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
⊢ 0 < eval x (cyclotomic n R)
state_after: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : ∏ i ∈ n.divisors.erase 1, cyclotomic i R = ∑ i ∈ range n, X ^ i
⊢ 0 < eval x (cyclotomic n R)

tactic: apply_fun eval x at this
state_before: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : ∏ i ∈ n.divisors.erase 1, cyclotomic i R = ∑ i ∈ range n, X ^ i
⊢ 0 < eval x (cyclotomic n R)
state_after: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (∏ i ∈ n.divisors.erase 1, cyclotomic i R) = eval x (∑ i ∈ range n, X ^ i)
⊢ 0 < eval x (cyclotomic n R)

tactic: rw [← cons_self_properDivisors hn'.ne', Finset.erase_cons_of_ne _ hn''.ne', Finset.prod_cons,
  eval_mul, eval_geom_sum] at this
state_before: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (∏ i ∈ n.divisors.erase 1, cyclotomic i R) = eval x (∑ i ∈ range n, X ^ i)
⊢ 0 < eval x (cyclotomic n R)
state_after: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
⊢ 0 < eval x (cyclotomic n R)

tactic: rcases lt_trichotomy 0 (∑ i ∈ Finset.range n, x ^ i) with (h | h | h)
state_before: case h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
⊢ 0 < eval x (cyclotomic n R)
state_after: case h.inl
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
⊢ 0 < eval x (cyclotomic n R)

case h.inr.inl
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 = ∑ i ∈ range n, x ^ i
⊢ 0 < eval x (cyclotomic n R)

case h.inr.inr
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : ∑ i ∈ range n, x ^ i < 0
⊢ 0 < eval x (cyclotomic n R)

tactic: apply pos_of_mul_pos_left
state_before: case h.inl
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
⊢ 0 < eval x (cyclotomic n R)
state_after: case h.inl.h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
⊢ 0 < eval x (cyclotomic n R) * ?h.inl.b

case h.inl.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
⊢ 0 ≤ ?h.inl.b

case h.inl.b
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
⊢ R

tactic: rw [eval_prod]
state_before: case h.inl.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
⊢ 0 ≤ eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R)
state_after: case h.inl.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
⊢ 0 ≤ ∏ j ∈ n.properDivisors.erase 1, eval x (cyclotomic j R)

tactic: refine Finset.prod_nonneg fun i hi => ?_
state_before: case h.inl.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
⊢ 0 ≤ ∏ j ∈ n.properDivisors.erase 1, eval x (cyclotomic j R)
state_after: case h.inl.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ∈ n.properDivisors.erase 1
⊢ 0 ≤ eval x (cyclotomic i R)

tactic: simp only [Finset.mem_erase, mem_properDivisors] at hi
state_before: case h.inl.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ∈ n.properDivisors.erase 1
⊢ 0 ≤ eval x (cyclotomic i R)
state_after: case h.inl.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
⊢ 0 ≤ eval x (cyclotomic i R)

tactic: rw [geom_sum_pos_iff hn'.ne'] at h
state_before: case h.inl.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
⊢ 0 ≤ eval x (cyclotomic i R)
state_after: case h.inl.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Odd n ∨ 0 < x + 1
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
⊢ 0 ≤ eval x (cyclotomic i R)

tactic: cases' h with hk hx
state_before: case h.inl.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Odd n ∨ 0 < x + 1
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
⊢ 0 ≤ eval x (cyclotomic i R)
state_after: case h.inl.hb.inl
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
hk : Odd n
⊢ 0 ≤ eval x (cyclotomic i R)

case h.inl.hb.inr
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
hx : 0 < x + 1
⊢ 0 ≤ eval x (cyclotomic i R)

tactic: rwa [this]
state_before: case h.inl.h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 < ∑ i ∈ range n, x ^ i
⊢ 0 < eval x (cyclotomic n R) * ?h.inl.b
state_after: no goals

tactic: refine (ih _ hi.2.2 (Nat.two_lt_of_ne ?_ hi.1 ?_)).le <;> rintro rfl
state_before: case h.inl.hb.inl
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
hk : Odd n
⊢ 0 ≤ eval x (cyclotomic i R)
state_after: case h.inl.hb.inl.refine_1
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
hk : Odd n
hi : 0 ≠ 1 ∧ 0 ∣ n ∧ 0 < n
⊢ False

case h.inl.hb.inl.refine_2
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
hk : Odd n
hi : 2 ≠ 1 ∧ 2 ∣ n ∧ 2 < n
⊢ False

tactic: exact hn'.ne' (zero_dvd_iff.mp hi.2.1)
state_before: case h.inl.hb.inl.refine_1
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
hk : Odd n
hi : 0 ≠ 1 ∧ 0 ∣ n ∧ 0 < n
⊢ False
state_after: no goals

tactic: exact even_iff_not_odd.mp (even_iff_two_dvd.mpr hi.2.1) hk
state_before: case h.inl.hb.inl.refine_2
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
hk : Odd n
hi : 2 ≠ 1 ∧ 2 ∣ n ∧ 2 < n
⊢ False
state_after: no goals

tactic: rcases eq_or_ne i 2 with (rfl | hk)
state_before: case h.inl.hb.inr
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
hx : 0 < x + 1
⊢ 0 ≤ eval x (cyclotomic i R)
state_after: case h.inl.hb.inr.inl
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
hx : 0 < x + 1
hi : 2 ≠ 1 ∧ 2 ∣ n ∧ 2 < n
⊢ 0 ≤ eval x (cyclotomic 2 R)

case h.inl.hb.inr.inr
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
hx : 0 < x + 1
hk : i ≠ 2
⊢ 0 ≤ eval x (cyclotomic i R)

tactic: refine (ih _ hi.2.2 (Nat.two_lt_of_ne ?_ hi.1 hk)).le
state_before: case h.inl.hb.inr.inr
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
hx : 0 < x + 1
hk : i ≠ 2
⊢ 0 ≤ eval x (cyclotomic i R)
state_after: case h.inl.hb.inr.inr
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
hx : 0 < x + 1
hk : i ≠ 2
⊢ i ≠ 0

tactic: rintro rfl
state_before: case h.inl.hb.inr.inr
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
i : ℕ
hi : i ≠ 1 ∧ i ∣ n ∧ i < n
hx : 0 < x + 1
hk : i ≠ 2
⊢ i ≠ 0
state_after: case h.inl.hb.inr.inr
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
hx : 0 < x + 1
hi : 0 ≠ 1 ∧ 0 ∣ n ∧ 0 < n
hk : 0 ≠ 2
⊢ False

tactic: exact hn'.ne' <| zero_dvd_iff.mp hi.2.1
state_before: case h.inl.hb.inr.inr
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
hx : 0 < x + 1
hi : 0 ≠ 1 ∧ 0 ∣ n ∧ 0 < n
hk : 0 ≠ 2
⊢ False
state_after: no goals

tactic: simpa only [eval_X, eval_one, cyclotomic_two, eval_add] using hx.le
state_before: case h.inl.hb.inr.inl
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
hx : 0 < x + 1
hi : 2 ≠ 1 ∧ 2 ∣ n ∧ 2 < n
⊢ 0 ≤ eval x (cyclotomic 2 R)
state_after: no goals

tactic: rw [eq_comm, geom_sum_eq_zero_iff_neg_one hn'.ne'] at h
state_before: case h.inr.inl
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : 0 = ∑ i ∈ range n, x ^ i
⊢ 0 < eval x (cyclotomic n R)
state_after: case h.inr.inl
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : x = -1 ∧ Even n
⊢ 0 < eval x (cyclotomic n R)

tactic: exact h.1.symm ▸ cyclotomic_neg_one_pos hn
state_before: case h.inr.inl
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : x = -1 ∧ Even n
⊢ 0 < eval x (cyclotomic n R)
state_after: no goals

tactic: apply pos_of_mul_neg_left
state_before: case h.inr.inr
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : ∑ i ∈ range n, x ^ i < 0
⊢ 0 < eval x (cyclotomic n R)
state_after: case h.inr.inr.h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : ∑ i ∈ range n, x ^ i < 0
⊢ eval x (cyclotomic n R) * ?h.inr.inr.b < 0

case h.inr.inr.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : ∑ i ∈ range n, x ^ i < 0
⊢ ?h.inr.inr.b ≤ 0

case h.inr.inr.b
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : ∑ i ∈ range n, x ^ i < 0
⊢ R

tactic: rw [geom_sum_neg_iff hn'.ne'] at h
state_before: case h.inr.inr.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : ∑ i ∈ range n, x ^ i < 0
⊢ eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) ≤ 0
state_after: case h.inr.inr.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
⊢ eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) ≤ 0

tactic: have h2 : 2 ∈ n.properDivisors.erase 1 := by
  rw [Finset.mem_erase, mem_properDivisors]
  exact ⟨by decide, even_iff_two_dvd.mp h.1, hn⟩
state_before: case h.inr.inr.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
⊢ eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) ≤ 0
state_after: case h.inr.inr.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
⊢ eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) ≤ 0

tactic: rw [eval_prod, ← Finset.prod_erase_mul _ _ h2]
state_before: case h.inr.inr.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
⊢ eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) ≤ 0
state_after: case h.inr.inr.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
⊢ (∏ x_1 ∈ (n.properDivisors.erase 1).erase 2, eval x (cyclotomic x_1 R)) * eval x (cyclotomic 2 R) ≤ 0

tactic: apply mul_nonpos_of_nonneg_of_nonpos
state_before: case h.inr.inr.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
⊢ (∏ x_1 ∈ (n.properDivisors.erase 1).erase 2, eval x (cyclotomic x_1 R)) * eval x (cyclotomic 2 R) ≤ 0
state_after: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
⊢ 0 ≤ ∏ x_1 ∈ (n.properDivisors.erase 1).erase 2, eval x (cyclotomic x_1 R)

case h.inr.inr.hb.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
⊢ eval x (cyclotomic 2 R) ≤ 0

tactic: rwa [this]
state_before: case h.inr.inr.h
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : ∑ i ∈ range n, x ^ i < 0
⊢ eval x (cyclotomic n R) * ?h.inr.inr.b < 0
state_after: no goals

tactic: rw [Finset.mem_erase, mem_properDivisors]
state_before: R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
⊢ 2 ∈ n.properDivisors.erase 1
state_after: R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
⊢ 2 ≠ 1 ∧ 2 ∣ n ∧ 2 < n

tactic: exact ⟨by decide, even_iff_two_dvd.mp h.1, hn⟩
state_before: R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
⊢ 2 ≠ 1 ∧ 2 ∣ n ∧ 2 < n
state_after: no goals

tactic: decide
state_before: R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
⊢ 2 ≠ 1
state_after: no goals

tactic: refine Finset.prod_nonneg fun i hi => le_of_lt ?_
state_before: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
⊢ 0 ≤ ∏ x_1 ∈ (n.properDivisors.erase 1).erase 2, eval x (cyclotomic x_1 R)
state_after: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
i : ℕ
hi : i ∈ (n.properDivisors.erase 1).erase 2
⊢ 0 < eval x (cyclotomic i R)

tactic: simp only [Finset.mem_erase, mem_properDivisors] at hi
state_before: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
i : ℕ
hi : i ∈ (n.properDivisors.erase 1).erase 2
⊢ 0 < eval x (cyclotomic i R)
state_after: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
i : ℕ
hi : i ≠ 2 ∧ i ≠ 1 ∧ i ∣ n ∧ i < n
⊢ 0 < eval x (cyclotomic i R)

tactic: refine ih _ hi.2.2.2 (Nat.two_lt_of_ne ?_ hi.2.1 hi.1)
state_before: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
i : ℕ
hi : i ≠ 2 ∧ i ≠ 1 ∧ i ∣ n ∧ i < n
⊢ 0 < eval x (cyclotomic i R)
state_after: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
i : ℕ
hi : i ≠ 2 ∧ i ≠ 1 ∧ i ∣ n ∧ i < n
⊢ i ≠ 0

tactic: rintro rfl
state_before: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
i : ℕ
hi : i ≠ 2 ∧ i ≠ 1 ∧ i ∣ n ∧ i < n
⊢ i ≠ 0
state_after: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
hi : 0 ≠ 2 ∧ 0 ≠ 1 ∧ 0 ∣ n ∧ 0 < n
⊢ False

tactic: rw [zero_dvd_iff] at hi
state_before: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
hi : 0 ≠ 2 ∧ 0 ≠ 1 ∧ 0 ∣ n ∧ 0 < n
⊢ False
state_after: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
hi : 0 ≠ 2 ∧ 0 ≠ 1 ∧ n = 0 ∧ 0 < n
⊢ False

tactic: exact hn'.ne' hi.2.2.1
state_before: case h.inr.inr.hb.ha
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
hi : 0 ≠ 2 ∧ 0 ≠ 1 ∧ n = 0 ∧ 0 < n
⊢ False
state_after: no goals

tactic: simpa only [eval_X, eval_one, cyclotomic_two, eval_add] using h.right.le
state_before: case h.inr.inr.hb.hb
R : Type u_1
inst✝ : LinearOrderedCommRing R
x : R
n : ℕ
ih : ∀ m < n, 2 < m → 0 < eval x (cyclotomic m R)
hn : 2 < n
hn' : 0 < n
hn'' : 1 < n
this : eval x (cyclotomic n R) * eval x (∏ x ∈ n.properDivisors.erase 1, cyclotomic x R) = ∑ i ∈ range n, x ^ i
h : Even n ∧ x + 1 < 0
h2 : 2 ∈ n.properDivisors.erase 1
⊢ eval x (cyclotomic 2 R) ≤ 0
state_after: no goals