-- Mathlib/NumberTheory/ClassNumber/AdmissibleCardPowDegree.lean
theorem cardPowDegree_anti_archimedean {x y z : Fq[X]} {a : ℤ} (hxy : cardPowDegree (x - y) < a)
    (hyz : cardPowDegree (y - z) < a) : cardPowDegree (x - z) < a

Proof state:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : ¬x = y
hyz' : ¬y = z
hxz' : ¬x = z
⊢ cardPowDegree (x - z) < a

Tactic:
rw [← Ne, ← sub_ne_zero] at hxy' hyz' hxz'

Result:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
⊢ cardPowDegree (x - z) < a

Proof state:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
this : 1 ≤ ↑(Fintype.card Fq)
⊢ ↑(Fintype.card Fq) ^ (x - z).natDegree ≤ ↑(Fintype.card Fq) ^ (x - y).natDegree ∨
    ↑(Fintype.card Fq) ^ (x - z).natDegree ≤ ↑(Fintype.card Fq) ^ (y - z).natDegree

Tactic:
refine Or.imp (pow_le_pow_right₀ this) (pow_le_pow_right₀ this) ?_

Result:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
this : 1 ≤ ↑(Fintype.card Fq)
⊢ (x - z).natDegree ≤ (x - y).natDegree ∨ (x - z).natDegree ≤ (y - z).natDegree

Proof state:
case pos
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x = y
⊢ cardPowDegree (x - z) < a

Tactic:
rwa [hxy']

Result:
no goals

Proof state:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
this : 1 ≤ ↑(Fintype.card Fq)
⊢ ↑(Fintype.card Fq) ^ (x - z).natDegree ≤
    ↑(Fintype.card Fq) ^ (x - y).natDegree ⊔ ↑(Fintype.card Fq) ^ (y - z).natDegree

Tactic:
simp only [Int.cast_pow, Int.cast_natCast, le_max_iff]

Result:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
this : 1 ≤ ↑(Fintype.card Fq)
⊢ ↑(Fintype.card Fq) ^ (x - z).natDegree ≤ ↑(Fintype.card Fq) ^ (x - y).natDegree ∨
    ↑(Fintype.card Fq) ^ (x - z).natDegree ≤ ↑(Fintype.card Fq) ^ (y - z).natDegree

Proof state:
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
⊢ cardPowDegree (x - z) < a

Tactic:
have ha : 0 < a := lt_of_le_of_lt (AbsoluteValue.nonneg _ _) hxy

Result:
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
⊢ cardPowDegree (x - z) < a

Proof state:
case pos
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : ¬x = y
hyz' : ¬y = z
hxz' : x = z
⊢ cardPowDegree (x - z) < a

Tactic:
rwa [hxz', sub_self, map_zero]

Result:
no goals

Proof state:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
⊢ cardPowDegree (x - z) ≤ cardPowDegree (x - y) ⊔ cardPowDegree (y - z)

Tactic:
rw [cardPowDegree_nonzero _ hxz', cardPowDegree_nonzero _ hxy',
  cardPowDegree_nonzero _ hyz']

Result:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
⊢ ↑(Fintype.card Fq) ^ (x - z).natDegree ≤
    ↑(Fintype.card Fq) ^ (x - y).natDegree ⊔ ↑(Fintype.card Fq) ^ (y - z).natDegree

Proof state:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
⊢ ↑(Fintype.card Fq) ^ (x - z).natDegree ≤
    ↑(Fintype.card Fq) ^ (x - y).natDegree ⊔ ↑(Fintype.card Fq) ^ (y - z).natDegree

Tactic:
have : (1 : ℤ) ≤ Fintype.card Fq := mod_cast (@Fintype.one_lt_card Fq _ _).le

Result:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
this : 1 ≤ ↑(Fintype.card Fq)
⊢ ↑(Fintype.card Fq) ^ (x - z).natDegree ≤
    ↑(Fintype.card Fq) ^ (x - y).natDegree ⊔ ↑(Fintype.card Fq) ^ (y - z).natDegree

Proof state:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : ¬x = y
hyz' : ¬y = z
⊢ cardPowDegree (x - z) < a

Tactic:
by_cases hxz' : x = z

Result:
case pos
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : ¬x = y
hyz' : ¬y = z
hxz' : x = z
⊢ cardPowDegree (x - z) < a

case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : ¬x = y
hyz' : ¬y = z
hxz' : ¬x = z
⊢ cardPowDegree (x - z) < a

Proof state:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : ¬x = y
⊢ cardPowDegree (x - z) < a

Tactic:
by_cases hyz' : y = z

Result:
case pos
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : ¬x = y
hyz' : y = z
⊢ cardPowDegree (x - z) < a

case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : ¬x = y
hyz' : ¬y = z
⊢ cardPowDegree (x - z) < a

Proof state:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
⊢ cardPowDegree (x - z) < a

Tactic:
refine lt_of_le_of_lt ?_ (max_lt hxy hyz)

Result:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
⊢ cardPowDegree (x - z) ≤ cardPowDegree (x - y) ⊔ cardPowDegree (y - z)

Proof state:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
this : 1 ≤ ↑(Fintype.card Fq)
⊢ (x - z).natDegree ≤ (x - y).natDegree ∨ (x - z).natDegree ≤ (y - z).natDegree

Tactic:
rw [natDegree_le_iff_degree_le, natDegree_le_iff_degree_le, ← le_max_iff, ←
  degree_eq_natDegree hxy', ← degree_eq_natDegree hyz']

Result:
case neg
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : x - y ≠ 0
hyz' : y - z ≠ 0
hxz' : x - z ≠ 0
this : 1 ≤ ↑(Fintype.card Fq)
⊢ (x - z).degree ≤ (x - y).degree ⊔ (y - z).degree

Proof state:
case pos
Fq : Type u_1
inst✝¹ : Fintype Fq
inst✝ : Field Fq
x y z : Fq[X]
a : ℤ
hxy : cardPowDegree (x - y) < a
hyz : cardPowDegree (y - z) < a
ha : 0 < a
hxy' : ¬x = y
hyz' : y = z
⊢ cardPowDegree (x - z) < a

Tactic:
rwa [← hyz']

Result:
no goals