OAI/GroupTheory/PolycyclicRecognition/Analysis/CoarsePathMesh.lean

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Finite meshes for paths with short jumps

The support-switch construction has a bounded number of logarithmically short switches. An additive coarse error in its parameterized path therefore contributes only the corresponding additive error to the height comparison.

  1. theorem OAI.PolycyclicRecognition.coarse_image_path_height_control line 23

    Source documentation

    Sampled height estimates control a whole coarse path, retaining the additive distance error explicitly.

    theorem coarse_image_path_height_control
        (p : NormalizedPair G Λ) (π : G →* Multiplicative W) (l : G →* Multiplicative W)
        {Lπ L r δ η ε κ : ℝ} (hLπ : 0 ≤ Lπ) (hL : 0 ≤ L) (hr : 0 ≤ r)
        (hπ : ∀ x y, ‖(π x).toAdd - (π y).toAdd‖ ≤ Lπ * dist x y)
        (γ : T → G) (hγ : ∀ t u, dist (γ t) (γ u) ≤ L * r * dist t u + κ)
        (S : Finset T) (hmesh : ∀ t, ∃ u ∈ S, dist t u ≤ δ)
        (E : Set W)
        (hheight : ∀ u ∈ S, ∃ w ∈ E, ‖(l (γ u)).toAdd - r • w‖ ≤ ε * r)
        (herror : ∀ u ∈ S, ‖pairHeight π (γ u) p - (l (γ u)).toAdd‖ ≤ η * r) :
        ∀ t, ∃ w ∈ E,
          ‖pairHeight π (γ t) p - r • w‖ ≤
            (Lπ * Λ * L * δ + η + ε) * r + Lπ * Λ * κ := by
    …

    Mentions: OAI.PolycyclicRecognition.NormalizedPair, OAI.PolycyclicRecognition.pairHeight