OAI/GroupTheory/PolycyclicRecognition/Analysis/TiledProbeSamplers.lean

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The three measurable samplers from an actual ideal tiling

  1. theorem OAI.PolycyclicRecognition.exists_measurable_tiled_probe_samplers line 24

    Source documentation

    A finite measurable tiling supplies the actual first-sheet, reverse-anchor, and within-tile samplers. Their group increments are the original endpoints, so choosing a tile never replaces a counted point by another representative.

    theorem exists_measurable_tiled_probe_samplers
        (ι : I →* N) (hι : Measurable ι) (φ : I ≃ₜ* I) (k : N)
        (hφ : ∀ z, ι (φ z) = k * ι z * k⁻¹)
        (σ : Z → N) (hσ : Measurable σ)
        (U Banchor Bsmall : Set I) {m : ℕ} (anchor : Fin m → I)
        (tile : Fin m → Set I) (hm : ∀ j, MeasurableSet (tile j))
        (hd : Pairwise (fun j l => Disjoint (tile j) (tile l)))
        (hu : (⋃ j, tile j) = U)
        (ha : ∀ j, φ.symm (anchor j) ∈ Banchor)
        (ht : ∀ j, tile j ⊆ anchor j • (φ '' Bsmall)) :
        ∃ (index : U → Fin m) (probe : Fin 3 → Z × U → N),
          Measurable index ∧ (∀ j, Measurable (probe j)) ∧
    …