OAI/GroupTheory/PolycyclicRecognition/Analysis/UnitSeparatedNet.lean

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3 declarations, 0 contain sorry, 0 declared as axioms

The locally finite unit net used for Lipschitz replacement

  1. theorem OAI.PolycyclicRecognition.exists_unit_separated_net line 20

    Source documentation

    A maximal unit-separated set covers the whole metric space by closed unit balls. No measure or geometric input is required for this step.

    theorem exists_unit_separated_net :
        ∃ V : Set X, V.Pairwise (fun x y => 1 < dist x y) ∧
          ∀ x : X, ∃ v ∈ V, dist x v ≤ 1 := by
    …
  2. theorem OAI.PolycyclicRecognition.finite_separated_subset_of_compact line 41

    Source documentation

    Compact sets contain only finitely many points of a unit-separated set.

    theorem finite_separated_subset_of_compact {V K : Set X}
        (hV : V.Pairwise (fun x y => 1 < dist x y)) (hK : IsCompact K) (hVK : V ⊆ K) :
        V.Finite := by
    …
  3. theorem OAI.PolycyclicRecognition.finite_unit_net_ball line 69

    Source documentation

    Every bounded part of the net is finite, giving the local finiteness needed to glue the cutoff partitions.

    theorem finite_unit_net_ball [ProperSpace X] {V : Set X}
        (hV : V.Pairwise (fun x y => 1 < dist x y)) (x : X) (R : ℝ) :
        (V ∩ Metric.closedBall x R).Finite :=
    …