x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
⊢ ∀ᶠ (ε : ℝ) in 𝓝 0, ∀ (m : ℤ), ε ≤ dist x (↑m / ↑n)
x : ℝ
hx : Irrational x
n : ℕ
⊢ ∀ᶠ (ε : ℝ) in 𝓝 0, ∀ (m : ℤ), ε ≤ dist x (↑m / ↑n)
have A : IsClosed (range (fun m => (n : ℝ)⁻¹ * m : ℤ → ℝ)) :=
  ((isClosedMap_smul₀ (n⁻¹ : ℝ)).comp Int.closedEmbedding_coe_real.isClosedMap).closed_range
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
B : ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
⊢ ∀ᶠ (ε : ℝ) in 𝓝 0, ∀ (m : ℤ), ε ≤ dist x (↑m / ↑n)
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
⊢ ∀ᶠ (ε : ℝ) in 𝓝 0, ∀ (m : ℤ), ε ≤ dist x (↑m / ↑n)
have B : x ∉ range (fun m => (n : ℝ)⁻¹ * m : ℤ → ℝ) := by
  rintro ⟨m, rfl⟩
  simp at hx
case intro.intro
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
B : ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
ε : ℝ
ε0 : ε > 0
hε : ball x ε ⊆ (range fun m => (↑n)⁻¹ * ↑m)ᶜ
⊢ ∀ᶠ (ε : ℝ) in 𝓝 0, ∀ (m : ℤ), ε ≤ dist x (↑m / ↑n)
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
B : ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
⊢ ∀ᶠ (ε : ℝ) in 𝓝 0, ∀ (m : ℤ), ε ≤ dist x (↑m / ↑n)
rcases Metric.mem_nhds_iff.1 (A.isOpen_compl.mem_nhds B) with ⟨ε, ε0, hε⟩
case intro.intro
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
B : ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
ε : ℝ
ε0 : ε > 0
hε : ball x ε ⊆ (range fun m => (↑n)⁻¹ * ↑m)ᶜ
δ : ℝ
hδ : δ ≤ ε
m : ℤ
hlt : dist x (↑m / ↑n) < δ
⊢ False
case intro.intro
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
B : ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
ε : ℝ
ε0 : ε > 0
hε : ball x ε ⊆ (range fun m => (↑n)⁻¹ * ↑m)ᶜ
⊢ ∀ᶠ (ε : ℝ) in 𝓝 0, ∀ (m : ℤ), ε ≤ dist x (↑m / ↑n)
refine' (ge_mem_nhds ε0).mono fun δ hδ m => not_lt.1 fun hlt => _
case intro.intro
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
B : ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
ε : ℝ
ε0 : ε > 0
hε : ball x ε ⊆ (range fun m => (↑n)⁻¹ * ↑m)ᶜ
δ : ℝ
hδ : δ ≤ ε
m : ℤ
hlt : dist (↑m / ↑n) x < δ
⊢ False
case intro.intro
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
B : ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
ε : ℝ
ε0 : ε > 0
hε : ball x ε ⊆ (range fun m => (↑n)⁻¹ * ↑m)ᶜ
δ : ℝ
hδ : δ ≤ ε
m : ℤ
hlt : dist x (↑m / ↑n) < δ
⊢ False
rw [dist_comm] at hlt
case intro.intro
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
B : ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
ε : ℝ
ε0 : ε > 0
hε : ball x ε ⊆ (range fun m => (↑n)⁻¹ * ↑m)ᶜ
δ : ℝ
hδ : δ ≤ ε
m : ℤ
hlt : dist (↑m / ↑n) x < δ
⊢ (fun m => (↑n)⁻¹ * ↑m) m = ↑m / ↑n
case intro.intro
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
B : ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
ε : ℝ
ε0 : ε > 0
hε : ball x ε ⊆ (range fun m => (↑n)⁻¹ * ↑m)ᶜ
δ : ℝ
hδ : δ ≤ ε
m : ℤ
hlt : dist (↑m / ↑n) x < δ
⊢ False
refine' hε (ball_subset_ball hδ hlt) ⟨m, _⟩
no goals
case intro.intro
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
B : ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
ε : ℝ
ε0 : ε > 0
hε : ball x ε ⊆ (range fun m => (↑n)⁻¹ * ↑m)ᶜ
δ : ℝ
hδ : δ ≤ ε
m : ℤ
hlt : dist (↑m / ↑n) x < δ
⊢ (fun m => (↑n)⁻¹ * ↑m) m = ↑m / ↑n
simp [div_eq_inv_mul]
case intro
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
m : ℤ
hx : Irrational ((fun m => (↑n)⁻¹ * ↑m) m)
⊢ False
x : ℝ
hx : Irrational x
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
⊢ ¬x ∈ range fun m => (↑n)⁻¹ * ↑m
rintro ⟨m, rfl⟩
no goals
case intro
n : ℕ
A : IsClosed (range fun m => (↑n)⁻¹ * ↑m)
m : ℤ
hx : Irrational ((fun m => (↑n)⁻¹ * ↑m) m)
⊢ False
simp at hx