OAI/Analysis/LipschitzHilbert/Geometry/DyadicLineCover.lean

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A uniform interval cover by the nested one-third dyadic grids.

  1. theorem OAI.LipschitzHilbert.DyadicLineGrid.unit_interval_cover line 14

    Source documentation

    The elementary one-third covering step at a fixed scale.

    theorem unit_interval_cover {a b δ : ℝ} (hδ0 : 1 / 3 ≤ δ) (hδ1 : δ ≤ 2 / 3)
        (hlen : b - a < 1 / 3) :
        (∃ j : ℤ, Icc a b ⊆ Ico (j : ℝ) (j + 1)) ∨
          ∃ j : ℤ, Icc a b ⊆ Ico ((j : ℝ) + δ) (j + 1 + δ) := by
    …
  2. theorem OAI.LipschitzHilbert.DyadicLineGrid.fixed_scale_interval_cover line 33

    Source documentation

    Each interval shorter than one third of a grid cell fits in one cell of the ordinary or alternating one-third grid.

    theorem fixed_scale_interval_cover (k : ℤ) {a b : ℝ} (hlen : b - a < scale k / 3) :
        ∃ q ∈ ({0, 1} : Finset ℤ), ∃ j : ℤ, Icc a b ⊆ cell q k j := by
    …

    Mentions: OAI.LipschitzHilbert.DyadicLineGrid.scale, OAI.LipschitzHilbert.DyadicLineGrid.cell

  3. theorem OAI.LipschitzHilbert.DyadicLineGrid.interval_cover line 87

    Source documentation

    A positive-length interval is contained in a dyadic interval of length at most six times its own, with one of two fixed nested grids.

    theorem interval_cover {a b : ℝ} (hab : a < b) :
        ∃ q ∈ ({0, 1} : Finset ℤ), ∃ k j : ℤ,
          Icc a b ⊆ cell q k j ∧ scale k ≤ 6 * (b - a) := by
    …

    Mentions: OAI.LipschitzHilbert.DyadicLineGrid.cell, OAI.LipschitzHilbert.DyadicLineGrid.scale