OAI/Geometry/RCD/Metric/RescalingSampleLimit.lean

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Subsequence limits of the sampled rescaling metrics

Uniformly bounded countable samples have a convergent distance matrix. Its triangle inequalities give an actual pseudometric, whose completion will supply the pointed limit after the finite-net estimates are applied.

  1. theorem OAI.RegularPointCoordinates.exists_rescaling_sample_limit line 24

    Source documentation

    A countable family of rescaled sample distances has an actual pseudometric subsequential limit. Only upper bounds on the samples are required at this stage.

    theorem exists_rescaling_sample_limit (r : ℕ → ℝ) (hr : ∀ i, 0 < r i)
        (points : ℕ → ι → X) (B : ι → ℝ)
        (hbound : ∀ k a b, dist (points k a) (points k b) / r k ≤ B a + B b) :
        ∃ phi : ℕ → ℕ, StrictMono phi ∧ ∃ d : PseudoMetricSpace ι,
          ∀ a b, Tendsto (fun k => dist (points (phi k) a) (points (phi k) b) / r (phi k))
            atTop (𝓝 (@dist ι d.toDist a b)) := by
    …