Theorem: one_le_pow_mul_abs_eval_div
File: Mathlib/Algebra/Polynomial/DenomsClearable.lean

Proof steps:
state_before: K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
⊢ 1 ≤ ↑b ^ f.natDegree * |eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f)|
state_after: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
⊢ 1 ≤ ↑b ^ f.natDegree * |eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f)|
tactic: obtain ⟨ev, bi, bu, hF⟩ :=
    denomsClearable_natDegree (b := b) (algebraMap ℤ K) f a
      (by
        rw [eq_intCast, one_div_mul_cancel]
        rw [Int.cast_ne_zero]
        exact b0.ne.symm)
state_before: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
⊢ 1 ≤ ↑b ^ f.natDegree * |eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f)|
state_after: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
Fa :
  |(algebraMap ℤ K) ev| =
    |(algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)|
⊢ 1 ≤ ↑b ^ f.natDegree * |eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f)|
tactic: obtain Fa := congr_arg abs hF
state_before: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
Fa :
  |(algebraMap ℤ K) ev| =
    |(algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)|
⊢ 1 ≤ ↑b ^ f.natDegree * |eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f)|
state_after: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
Fa : |↑ev| = |↑b ^ f.natDegree| * |eval ((algebraMap ℤ K) a * (1 / ↑b)) (Polynomial.map (algebraMap ℤ K) f)|
⊢ 1 ≤ ↑b ^ f.natDegree * |eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f)|
tactic: rw [eq_one_div_of_mul_eq_one_left bu, eq_intCast, eq_intCast, abs_mul] at Fa
state_before: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
Fa : |↑ev| = |↑b ^ f.natDegree| * |eval ((algebraMap ℤ K) a * (1 / ↑b)) (Polynomial.map (algebraMap ℤ K) f)|
⊢ 1 ≤ ↑b ^ f.natDegree * |eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f)|
state_after: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
Fa : |↑ev| = ↑b ^ f.natDegree * |eval (↑a * (↑b)⁻¹) (Polynomial.map (algebraMap ℤ K) f)|
⊢ 1 ≤ ↑b ^ f.natDegree * |eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f)|
tactic: rw [abs_of_pos (pow_pos (Int.cast_pos.mpr b0) _ : 0 < (b : K) ^ _), one_div, eq_intCast] at Fa
state_before: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
Fa : |↑ev| = ↑b ^ f.natDegree * |eval (↑a * (↑b)⁻¹) (Polynomial.map (algebraMap ℤ K) f)|
⊢ 1 ≤ ↑b ^ f.natDegree * |eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f)|
state_after: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
Fa : |↑ev| = ↑b ^ f.natDegree * |eval (↑a * (↑b)⁻¹) (Polynomial.map (algebraMap ℤ K) f)|
⊢ 1 ≤ |ev|
tactic: rw [div_eq_mul_inv, ← Fa, ← Int.cast_abs, ← Int.cast_one, Int.cast_le]
state_before: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
Fa : |↑ev| = ↑b ^ f.natDegree * |eval (↑a * (↑b)⁻¹) (Polynomial.map (algebraMap ℤ K) f)|
⊢ 1 ≤ |ev|
state_after: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
Fa : |↑ev| = ↑b ^ f.natDegree * |eval (↑a * (↑b)⁻¹) (Polynomial.map (algebraMap ℤ K) f)|
F0 : ev = 0
⊢ eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) = 0
tactic: refine Int.le_of_lt_add_one ((lt_add_iff_pos_left 1).mpr (abs_pos.mpr fun F0 => fab ?_))
state_before: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) ev =
    (algebraMap ℤ K) b ^ f.natDegree * eval ((algebraMap ℤ K) a * bi) (Polynomial.map (algebraMap ℤ K) f)
Fa : |↑ev| = ↑b ^ f.natDegree * |eval (↑a * (↑b)⁻¹) (Polynomial.map (algebraMap ℤ K) f)|
F0 : ev = 0
⊢ eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) = 0
state_after: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) b ^ f.natDegree = 0 ∨
    eval ((algebraMap ℤ K) a * ((algebraMap ℤ K) b)⁻¹) (Polynomial.map (algebraMap ℤ K) f) = 0
Fa : |↑ev| = ↑b ^ f.natDegree * |eval (↑a * (↑b)⁻¹) (Polynomial.map (algebraMap ℤ K) f)|
F0 : ev = 0
⊢ eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) = 0
tactic: rw [eq_one_div_of_mul_eq_one_left bu, F0, one_div, eq_intCast, Int.cast_zero, zero_eq_mul] at hF
state_before: case intro.intro.intro
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
hF :
  (algebraMap ℤ K) b ^ f.natDegree = 0 ∨
    eval ((algebraMap ℤ K) a * ((algebraMap ℤ K) b)⁻¹) (Polynomial.map (algebraMap ℤ K) f) = 0
Fa : |↑ev| = ↑b ^ f.natDegree * |eval (↑a * (↑b)⁻¹) (Polynomial.map (algebraMap ℤ K) f)|
F0 : ev = 0
⊢ eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) = 0
state_after: case intro.intro.intro.inl
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
Fa : |↑ev| = ↑b ^ f.natDegree * |eval (↑a * (↑b)⁻¹) (Polynomial.map (algebraMap ℤ K) f)|
F0 : ev = 0
hF : (algebraMap ℤ K) b ^ f.natDegree = 0
⊢ eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) = 0

case intro.intro.intro.inr
K : Type u_1
inst✝ : LinearOrderedField K
f : ℤ[X]
a b : ℤ
b0 : 0 < b
fab : eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) ≠ 0
ev : ℤ
bi : K
bu : bi * (algebraMap ℤ K) b = 1
Fa : |↑ev| = ↑b ^ f.natDegree * |eval (↑a * (↑b)⁻¹) (Polynomial.map (algebraMap ℤ K) f)|
F0 : ev = 0
hF : eval ((algebraMap ℤ K) a * ((algebraMap ℤ K) b)⁻¹) (Polynomial.map (algebraMap ℤ K) f) = 0
⊢ eval (↑a / ↑b) (Polynomial.map (algebraMap ℤ K) f) = 0
tactic: cases' hF with hF hF