OAI/Geometry/RCD/Metric/VolumeDensity.lean

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The small-scale Hausdorff-volume upper bound

The CD-derived Hausdorff ball estimate has an exponential factor tending to one. It supplies the exact small-scale density input for every nonnegative comparison curvature parameter.

  1. theorem OAI.RegularPointCoordinates.NoncollapsedRCD.normalized_ball_volume_upper line 24

    Source documentation

    The normalized Hausdorff volume has the explicit CD exponential upper bound, with its exact Euclidean normalization.

    theorem NoncollapsedRCD.normalized_ball_volume_upper {K : ℝ} {n : ℕ}
        (hX : NoncollapsedRCD K n X) (hn : 2 ≤ n) (p : X) {r : ℝ} (hr : 0 < r) :
        (hausdorff n X).real (ball p r) ≤
          (euclideanUnitVolume n *
            Real.exp (2*r*Real.sqrt (|K|/((n:ℝ)-1))) ^ n) * r ^ n := by
    …

    Mentions: OAI.RegularPointCoordinates.NoncollapsedRCD, OAI.RegularPointCoordinates.hausdorff, OAI.RegularPointCoordinates.euclideanUnitVolume

  2. theorem OAI.RegularPointCoordinates.NoncollapsedRCD.smallScaleVolumeUpper line 48

    Source documentation

    The CD Hausdorff estimate implies the exact small-scale volume upper bound for every nonnegative comparison curvature parameter.

    theorem NoncollapsedRCD.smallScaleVolumeUpper {K : ℝ} {n : ℕ}
        (hX : NoncollapsedRCD K n X) (hn : 2 ≤ n) {a : ℝ} (ha : 0 ≤ a) (p : X) :
        SmallScaleVolumeUpper (hausdorff n X) (comparisonModelVolume (n-1) a)
          p (euclideanUnitVolume n) := by
    …

    Mentions: OAI.RegularPointCoordinates.NoncollapsedRCD, OAI.RegularPointCoordinates.SmallScaleVolumeUpper, OAI.RegularPointCoordinates.hausdorff, OAI.RegularPointCoordinates.comparisonModelVolume, OAI.RegularPointCoordinates.euclideanUnitVolume