OAI/Geometry/RCD/Coordinates/UniformControlledNormalization.lean

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Uniform normalization at nearby centers

A single harmonic map on the enlarged initial ball supplies the maps at all nearby centers. Only the volume-ratio cost is paid when its first-order splitting data are restricted. The resulting normalizers and approximation bounds are uniform in the center and in every smaller scale.

  1. theorem OAI.RegularPointCoordinates.uniform_controlled_coordinates line 27

    Source documentation

    Uniform first-order data and all-center flatness give actual normalized harmonic coordinates at every center in the inner quarter-ball.

    theorem uniform_controlled_coordinates {K : ℝ} {n : ℕ}
        (hX : NoncollapsedRCD K n X) (hn : 2 ≤ n)
        (htrans : LocalTransformationInput hX) (hsplit : LocalFlatSplittingInput hX)
        {ρ β C : ℝ} (hρ : 0 < ρ) (hβ : 0 < β) (hC : 1 ≤ C) :
        ∃ δ : ℝ, 0 < δ ∧ ∀ (p : X) (R : ℝ), 0 < R → -δ ≤ K * R ^ 2 →
          ∀ (u : Fin n → SobolevSpace (hausdorff n X) hX.quadratic) (v : X → Euclidean n),
            FirstOrderSplittingOn (hausdorff n X) hX.quadratic p (2 * R) δ u v →
            (∀ q ∈ ball p (R / 4),
              (hausdorff n X).real (ball p (2 * R)) ≤
                C * (hausdorff n X).real (ball q (R / 2))) →
            (∀ q ∈ ball p (R / 4), ∀ s : ℝ, 0 < s → s ≤ R / 4 →
              ∃ f : X → Euclidean n, IsPointedApproximation q 0 s 2 δ f) →
    …

    Mentions: OAI.RegularPointCoordinates.NoncollapsedRCD, OAI.RegularPointCoordinates.LocalTransformationInput, OAI.RegularPointCoordinates.LocalFlatSplittingInput, OAI.RegularPointCoordinates.SobolevSpace, OAI.RegularPointCoordinates.hausdorff, OAI.RegularPointCoordinates.Euclidean, OAI.RegularPointCoordinates.FirstOrderSplittingOn, OAI.RegularPointCoordinates.IsPointedApproximation

  2. theorem OAI.RegularPointCoordinates.uniform_controlled_coordinates_of_comparison line 93

    Source documentation

    The volume-ratio premise is supplied by Bishop--Gromov with a fixed constant depending only on dimension.

    theorem uniform_controlled_coordinates_of_comparison {K : ℝ} (m : ℕ)
        (hX : NoncollapsedRCD K (m + 1) X) (hn : 2 ≤ m + 1)
        (htrans : LocalTransformationInput hX) (hsplit : LocalFlatSplittingInput hX)
        {a : ℝ} (ha : 0 ≤ a)
        (hBG : BallVolumeComparison (hausdorff (m + 1) X) (comparisonModelVolume m a))
        {ρ β : ℝ} (hρ : 0 < ρ) (hβ : 0 < β) :
        ∃ δ : ℝ, 0 < δ ∧ ∀ (p : X) (R : ℝ), 0 < R → -δ ≤ K * R ^ 2 →
          a * (3 * R) ≤ 1 →
          ∀ (u : Fin (m + 1) → SobolevSpace (hausdorff (m + 1) X) hX.quadratic)
            (v : X → Euclidean (m + 1)),
            FirstOrderSplittingOn (hausdorff (m + 1) X) hX.quadratic p (2 * R) δ u v →
            (∀ q ∈ ball p (R / 4), ∀ s : ℝ, 0 < s → s ≤ R / 4 →
    …

    Mentions: OAI.RegularPointCoordinates.NoncollapsedRCD, OAI.RegularPointCoordinates.LocalTransformationInput, OAI.RegularPointCoordinates.LocalFlatSplittingInput, OAI.RegularPointCoordinates.BallVolumeComparison, OAI.RegularPointCoordinates.hausdorff, OAI.RegularPointCoordinates.comparisonModelVolume, OAI.RegularPointCoordinates.SobolevSpace, OAI.RegularPointCoordinates.Euclidean, OAI.RegularPointCoordinates.FirstOrderSplittingOn