Theorem: Polynomial.isUnitTrinomial_iff
File: Mathlib/Algebra/Polynomial/UnitTrinomial.lean

Proof steps:
state_before: p q : ℤ[X]
⊢ p.IsUnitTrinomial ↔ p.support.card = 3 ∧ ∀ k ∈ p.support, IsUnit (p.coeff k)
state_after: p q : ℤ[X]
hp : p.support.card = 3 ∧ ∀ k ∈ p.support, IsUnit (p.coeff k)
⊢ p.IsUnitTrinomial
tactic: refine ⟨fun hp => ⟨hp.card_support_eq_three, fun k => hp.coeff_isUnit⟩, fun hp => ?_⟩
state_before: p q : ℤ[X]
hp : p.support.card = 3 ∧ ∀ k ∈ p.support, IsUnit (p.coeff k)
⊢ p.IsUnitTrinomial
state_after: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hx : x ≠ 0
hy : y ≠ 0
hz : z ≠ 0
hp :
  (C x * X ^ k + C y * X ^ m + C z * X ^ n).support.card = 3 ∧
    ∀ k_1 ∈ (C x * X ^ k + C y * X ^ m + C z * X ^ n).support,
      IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
tactic: obtain ⟨k, m, n, hkm, hmn, x, y, z, hx, hy, hz, rfl⟩ := card_support_eq_three.mp hp.1
state_before: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hx : x ≠ 0
hy : y ≠ 0
hz : z ≠ 0
hp :
  (C x * X ^ k + C y * X ^ m + C z * X ^ n).support.card = 3 ∧
    ∀ k_1 ∈ (C x * X ^ k + C y * X ^ m + C z * X ^ n).support,
      IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
state_after: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hx : x ≠ 0
hy : y ≠ 0
hz : z ≠ 0
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
tactic: rw [support_trinomial hkm hmn hx hy hz] at hp
state_before: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hx : x ≠ 0
hy : y ≠ 0
hz : z ≠ 0
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
state_after: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hy : y ≠ 0
hz : z ≠ 0
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
tactic: replace hx := hp.2 k (mem_insert_self k {m, n})
state_before: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hy : y ≠ 0
hz : z ≠ 0
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
state_after: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hz : z ≠ 0
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k)
hy : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff m)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
tactic: replace hy := hp.2 m (mem_insert_of_mem (mem_insert_self m {n}))
state_before: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hz : z ≠ 0
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k)
hy : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff m)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
state_after: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k)
hy : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff m)
hz : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff n)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
tactic: replace hz := hp.2 n (mem_insert_of_mem (mem_insert_of_mem (mem_singleton_self n)))
state_before: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k)
hy : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff m)
hz : IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff n)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
state_after: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit ((x + y * if k = m then 1 else 0) + z * if k = n then 1 else 0)
hy : IsUnit ((x * if m = k then 1 else 0) + y + z * if m = n then 1 else 0)
hz : IsUnit (((x * if n = k then 1 else 0) + y * if n = m then 1 else 0) + z)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
tactic: simp_rw [coeff_add, coeff_C_mul, coeff_X_pow_self, mul_one, coeff_X_pow] at hx hy hz
state_before: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit ((x + y * if k = m then 1 else 0) + z * if k = n then 1 else 0)
hy : IsUnit ((x * if m = k then 1 else 0) + y + z * if m = n then 1 else 0)
hz : IsUnit (((x * if n = k then 1 else 0) + y * if n = m then 1 else 0) + z)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
state_after: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit (x + y * 0 + z * 0)
hy : IsUnit ((x * if m = k then 1 else 0) + y + z * if m = n then 1 else 0)
hz : IsUnit (((x * if n = k then 1 else 0) + y * if n = m then 1 else 0) + z)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
tactic: rw [if_neg hkm.ne, if_neg (hkm.trans hmn).ne] at hx
state_before: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit (x + y * 0 + z * 0)
hy : IsUnit ((x * if m = k then 1 else 0) + y + z * if m = n then 1 else 0)
hz : IsUnit (((x * if n = k then 1 else 0) + y * if n = m then 1 else 0) + z)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
state_after: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit (x + y * 0 + z * 0)
hy : IsUnit (x * 0 + y + z * 0)
hz : IsUnit (((x * if n = k then 1 else 0) + y * if n = m then 1 else 0) + z)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
tactic: rw [if_neg hkm.ne', if_neg hmn.ne] at hy
state_before: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit (x + y * 0 + z * 0)
hy : IsUnit (x * 0 + y + z * 0)
hz : IsUnit (((x * if n = k then 1 else 0) + y * if n = m then 1 else 0) + z)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
state_after: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit (x + y * 0 + z * 0)
hy : IsUnit (x * 0 + y + z * 0)
hz : IsUnit (x * 0 + y * 0 + z)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
tactic: rw [if_neg (hkm.trans hmn).ne', if_neg hmn.ne'] at hz
state_before: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hx : IsUnit (x + y * 0 + z * 0)
hy : IsUnit (x * 0 + y + z * 0)
hz : IsUnit (x * 0 + y * 0 + z)
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
state_after: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hz : IsUnit z
hx : IsUnit x
hy : IsUnit y
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
tactic: simp_rw [mul_zero, zero_add, add_zero] at hx hy hz
state_before: case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
q : ℤ[X]
k m n : ℕ
hkm : k < m
hmn : m < n
x y z : ℤ
hp : {k, m, n}.card = 3 ∧ ∀ k_1 ∈ {k, m, n}, IsUnit ((C x * X ^ k + C y * X ^ m + C z * X ^ n).coeff k_1)
hz : IsUnit z
hx : IsUnit x
hy : IsUnit y
⊢ (C x * X ^ k + C y * X ^ m + C z * X ^ n).IsUnitTrinomial
state_after: no goals
tactic: exact ⟨k, m, n, hkm, hmn, hx.unit, hy.unit, hz.unit, rfl⟩