l3lab/ntp-mathlib huggingface dataset:
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  

Proof state:
case neg.intro.intro.intro.intro.principal'
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
⊢ ∃ a, I = Submodule.span R {a}

Next tactic:
use p ^ Nat.find ex
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  

Proof state:
case h
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
⊢ I = Submodule.span R {p ^ Nat.find ex}

Next tactic:
show I = Ideal.span _
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  

Proof state:
case h
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
⊢ I = span {p ^ Nat.find ex}

Next tactic:
apply le_antisymm
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  apply le_antisymm
  · 

Proof state:
case h.a
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
⊢ I ≤ span {p ^ Nat.find ex}

Next tactic:
intro r hr
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  apply le_antisymm
  · intro r hr
    

Proof state:
case h.a
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
r : R
hr : r ∈ I
⊢ r ∈ span {p ^ Nat.find ex}

Next tactic:
by_cases hr0 : r = 0
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  apply le_antisymm
  · intro r hr
    by_cases hr0 : r = 0
    · 

Proof state:
case pos
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
r : R
hr : r ∈ I
hr0 : r = 0
⊢ r ∈ span {p ^ Nat.find ex}

Next tactic:
simp only [hr0, Submodule.zero_mem]
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  apply le_antisymm
  · intro r hr
    by_cases hr0 : r = 0
    · simp only [hr0, Submodule.zero_mem]
    

Proof state:
case neg
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
r : R
hr : r ∈ I
hr0 : ¬r = 0
⊢ r ∈ span {p ^ Nat.find ex}

Next tactic:
obtain ⟨n, u, rfl⟩ := H hr0
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  apply le_antisymm
  · intro r hr
    by_cases hr0 : r = 0
    · simp only [hr0, Submodule.zero_mem]
    obtain ⟨n, u, rfl⟩ := H hr0
    

Proof state:
case neg.intro.intro
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
n : ℕ
u : Rˣ
hr : p ^ n * ↑u ∈ I
hr0 : ¬p ^ n * ↑u = 0
⊢ p ^ n * ↑u ∈ span {p ^ Nat.find ex}

Next tactic:
simp only [mem_span_singleton, Units.isUnit, IsUnit.dvd_mul_right]
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  apply le_antisymm
  · intro r hr
    by_cases hr0 : r = 0
    · simp only [hr0, Submodule.zero_mem]
    obtain ⟨n, u, rfl⟩ := H hr0
    simp only [mem_span_singleton, Units.isUnit, IsUnit.dvd_mul_right]
    

Proof state:
case neg.intro.intro
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
n : ℕ
u : Rˣ
hr : p ^ n * ↑u ∈ I
hr0 : ¬p ^ n * ↑u = 0
⊢ p ^ Nat.find ex ∣ p ^ n

Next tactic:
apply pow_dvd_pow
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  apply le_antisymm
  · intro r hr
    by_cases hr0 : r = 0
    · simp only [hr0, Submodule.zero_mem]
    obtain ⟨n, u, rfl⟩ := H hr0
    simp only [mem_span_singleton, Units.isUnit, IsUnit.dvd_mul_right]
    apply pow_dvd_pow
    

Proof state:
case neg.intro.intro.h
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
n : ℕ
u : Rˣ
hr : p ^ n * ↑u ∈ I
hr0 : ¬p ^ n * ↑u = 0
⊢ Nat.find ex ≤ n

Next tactic:
apply Nat.find_min'
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  apply le_antisymm
  · intro r hr
    by_cases hr0 : r = 0
    · simp only [hr0, Submodule.zero_mem]
    obtain ⟨n, u, rfl⟩ := H hr0
    simp only [mem_span_singleton, Units.isUnit, IsUnit.dvd_mul_right]
    apply pow_dvd_pow
    apply Nat.find_min'
    

Proof state:
case neg.intro.intro.h.h
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
n : ℕ
u : Rˣ
hr : p ^ n * ↑u ∈ I
hr0 : ¬p ^ n * ↑u = 0
⊢ p ^ n ∈ I

Next tactic:
simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hr
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  apply le_antisymm
  · intro r hr
    by_cases hr0 : r = 0
    · simp only [hr0, Submodule.zero_mem]
    obtain ⟨n, u, rfl⟩ := H hr0
    simp only [mem_span_singleton, Units.isUnit, IsUnit.dvd_mul_right]
    apply pow_dvd_pow
    apply Nat.find_min'
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hr
  · 

Proof state:
case h.a
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
⊢ span {p ^ Nat.find ex} ≤ I

Next tactic:
erw [Submodule.span_singleton_le_iff_mem]
theorem aux_pid_of_ufd_of_unique_irreducible (R : Type u) [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    IsPrincipalIdealRing R := by
  constructor
  intro I
  by_cases I0 : I = ⊥
  · rw [I0]
    use 0
    simp only [Set.singleton_zero, Submodule.span_zero]
  obtain ⟨x, hxI, hx0⟩ : ∃ x ∈ I, x ≠ (0 : R) := I.ne_bot_iff.mp I0
  obtain ⟨p, _, H⟩ := HasUnitMulPowIrreducibleFactorization.of_ufd_of_unique_irreducible h₁ h₂
  have ex : ∃ n : ℕ, p ^ n ∈ I := by
    obtain ⟨n, u, rfl⟩ := H hx0
    refine' ⟨n, _⟩
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hxI
  constructor
  use p ^ Nat.find ex
  show I = Ideal.span _
  apply le_antisymm
  · intro r hr
    by_cases hr0 : r = 0
    · simp only [hr0, Submodule.zero_mem]
    obtain ⟨n, u, rfl⟩ := H hr0
    simp only [mem_span_singleton, Units.isUnit, IsUnit.dvd_mul_right]
    apply pow_dvd_pow
    apply Nat.find_min'
    simpa only [Units.mul_inv_cancel_right] using I.mul_mem_right (↑u⁻¹) hr
  · erw [Submodule.span_singleton_le_iff_mem]
    

Proof state:
case h.a
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
I : Ideal R
I0 : ¬I = ⊥
x : R
hxI : x ∈ I
hx0 : x ≠ 0
p : R
left✝ : Irreducible p
H : ∀ {x : R}, x ≠ 0 → ∃ n, Associated (p ^ n) x
ex : ∃ n, p ^ n ∈ I
⊢ p ^ Nat.find ex ∈ I

Next tactic:
exact Nat.find_spec ex
/-- A unique factorization domain with at least one irreducible element
in which all irreducible elements are associated
is a discrete valuation ring.
-/
theorem of_ufd_of_unique_irreducible {R : Type u} [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    DiscreteValuationRing R := by
  

Proof state:
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
⊢ DiscreteValuationRing R

Next tactic:
rw [iff_pid_with_one_nonzero_prime]
/-- A unique factorization domain with at least one irreducible element
in which all irreducible elements are associated
is a discrete valuation ring.
-/
theorem of_ufd_of_unique_irreducible {R : Type u} [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    DiscreteValuationRing R := by
  rw [iff_pid_with_one_nonzero_prime]
  

Proof state:
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
⊢ IsPrincipalIdealRing R ∧ ∃! P, P ≠ ⊥ ∧ IsPrime P

Next tactic:
haveI PID : IsPrincipalIdealRing R := aux_pid_of_ufd_of_unique_irreducible R h₁ h₂
/-- A unique factorization domain with at least one irreducible element
in which all irreducible elements are associated
is a discrete valuation ring.
-/
theorem of_ufd_of_unique_irreducible {R : Type u} [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    DiscreteValuationRing R := by
  rw [iff_pid_with_one_nonzero_prime]
  haveI PID : IsPrincipalIdealRing R := aux_pid_of_ufd_of_unique_irreducible R h₁ h₂
  

Proof state:
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₁ : ∃ p, Irreducible p
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
PID : IsPrincipalIdealRing R
⊢ IsPrincipalIdealRing R ∧ ∃! P, P ≠ ⊥ ∧ IsPrime P

Next tactic:
obtain ⟨p, hp⟩ := h₁
/-- A unique factorization domain with at least one irreducible element
in which all irreducible elements are associated
is a discrete valuation ring.
-/
theorem of_ufd_of_unique_irreducible {R : Type u} [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    DiscreteValuationRing R := by
  rw [iff_pid_with_one_nonzero_prime]
  haveI PID : IsPrincipalIdealRing R := aux_pid_of_ufd_of_unique_irreducible R h₁ h₂
  obtain ⟨p, hp⟩ := h₁
  

Proof state:
case intro
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
PID : IsPrincipalIdealRing R
p : R
hp : Irreducible p
⊢ IsPrincipalIdealRing R ∧ ∃! P, P ≠ ⊥ ∧ IsPrime P

Next tactic:
refine' ⟨PID, ⟨Ideal.span {p}, ⟨_, _⟩, _⟩⟩
/-- A unique factorization domain with at least one irreducible element
in which all irreducible elements are associated
is a discrete valuation ring.
-/
theorem of_ufd_of_unique_irreducible {R : Type u} [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    DiscreteValuationRing R := by
  rw [iff_pid_with_one_nonzero_prime]
  haveI PID : IsPrincipalIdealRing R := aux_pid_of_ufd_of_unique_irreducible R h₁ h₂
  obtain ⟨p, hp⟩ := h₁
  refine' ⟨PID, ⟨Ideal.span {p}, ⟨_, _⟩, _⟩⟩
  · 

Proof state:
case intro.refine'_1
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
PID : IsPrincipalIdealRing R
p : R
hp : Irreducible p
⊢ span {p} ≠ ⊥

Next tactic:
rw [Submodule.ne_bot_iff]
/-- A unique factorization domain with at least one irreducible element
in which all irreducible elements are associated
is a discrete valuation ring.
-/
theorem of_ufd_of_unique_irreducible {R : Type u} [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    DiscreteValuationRing R := by
  rw [iff_pid_with_one_nonzero_prime]
  haveI PID : IsPrincipalIdealRing R := aux_pid_of_ufd_of_unique_irreducible R h₁ h₂
  obtain ⟨p, hp⟩ := h₁
  refine' ⟨PID, ⟨Ideal.span {p}, ⟨_, _⟩, _⟩⟩
  · rw [Submodule.ne_bot_iff]
    

Proof state:
case intro.refine'_1
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
PID : IsPrincipalIdealRing R
p : R
hp : Irreducible p
⊢ ∃ x ∈ span {p}, x ≠ 0

Next tactic:
refine' ⟨p, Ideal.mem_span_singleton.mpr (dvd_refl p), hp.ne_zero⟩
/-- A unique factorization domain with at least one irreducible element
in which all irreducible elements are associated
is a discrete valuation ring.
-/
theorem of_ufd_of_unique_irreducible {R : Type u} [CommRing R] [IsDomain R]
    [UniqueFactorizationMonoid R] (h₁ : ∃ p : R, Irreducible p)
    (h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q) :
    DiscreteValuationRing R := by
  rw [iff_pid_with_one_nonzero_prime]
  haveI PID : IsPrincipalIdealRing R := aux_pid_of_ufd_of_unique_irreducible R h₁ h₂
  obtain ⟨p, hp⟩ := h₁
  refine' ⟨PID, ⟨Ideal.span {p}, ⟨_, _⟩, _⟩⟩
  · rw [Submodule.ne_bot_iff]
    refine' ⟨p, Ideal.mem_span_singleton.mpr (dvd_refl p), hp.ne_zero⟩
  · 

Proof state:
case intro.refine'_2
R✝ : Type u_1
R : Type u
inst✝² : CommRing R
inst✝¹ : IsDomain R
inst✝ : UniqueFactorizationMonoid R
h₂ : ∀ ⦃p q : R⦄, Irreducible p → Irreducible q → Associated p q
PID : IsPrincipalIdealRing R
p : R
hp : Irreducible p
⊢ IsPrime (span {p})

Next tactic:
rwa [Ideal.span_singleton_prime hp.ne_zero, ← UniqueFactorizationMonoid.irreducible_iff_prime]