theorem
proved
nat_diagonal_extraction
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IndisputableMonolith.NavierStokes.FourierExtraction on GitHub at line 159.
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156
157/-- **Cantor diagonal extraction** for ℕ-indexed bounded sequences
158in a proper metric space. Fully proved. -/
159theorem nat_diagonal_extraction {X : Type*} [MetricSpace X] [ProperSpace X]
160 (f : ℕ → ℕ → X) (c : X) (R : ℝ)
161 (hf : ∀ n m, dist (f n m) c ≤ R) :
162 ∃ (φ : ℕ → ℕ) (g : ℕ → X), StrictMono φ ∧
163 ∀ m, Tendsto (fun n => f (φ n) m) atTop (𝓝 (g m)) :=
164 ⟨D f c R hf, CL f c R hf, D_strictMono f c R hf, D_converges f c R hf⟩
165
166end IndisputableMonolith.NavierStokes.FourierExtraction