OAI/GroupTheory/PolycyclicRecognition/Analysis/StationaryCentered.lean

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The zero-mean Hilbert representation and stationary sublinearity

The closed kernel of integration is invariant under inverse pullback. Ergodicity removes its invariant vectors. This constructs the representation to which the published reduced-cohomology input is applied; the conclusion is the manuscript's averaged sublinear estimate for a fixed measure.

  1. abbrev OAI.PolycyclicRecognition.ZeroMeanL2 line 30

    Source documentation

    The actual closed zero-mean subspace of L².

    abbrev ZeroMeanL2 : Submodule ℝ (Lp W 2 μ) := (stationaryL2Mean (W := W) μ).ker

    Mentions: OAI.PolycyclicRecognition.stationaryL2Mean

  2. theorem OAI.PolycyclicRecognition.stationaryL2Mean_const line 33

    Source documentation

    Constants have their stated mean on a probability space.

    theorem stationaryL2Mean_const (w : W) : stationaryL2Mean μ (Lp.const 2 μ w) = w := by
    …

    Mentions: OAI.PolycyclicRecognition.stationaryL2Mean

  3. theorem OAI.PolycyclicRecognition.stationaryPullback_const line 40

    Source documentation

    Constant functions are fixed by inverse pullback.

    theorem stationaryPullback_const (g : G) (w : W) :
        stationaryPullback μ g (Lp.const 2 μ w) = Lp.const 2 μ w := by
    …

    Mentions: OAI.PolycyclicRecognition.stationaryPullback

  4. def OAI.PolycyclicRecognition.zeroMeanL2Action line 50

    Source documentation

    Restrict the pullback representation to the kernel of integration.

    def zeroMeanL2Action : DistribMulAction G (ZeroMeanL2 (W := W) μ) where
    …

    Mentions: OAI.PolycyclicRecognition.ZeroMeanL2

  5. instance OAI.PolycyclicRecognition.zeroMeanL2Isometric line 62
  6. instance OAI.PolycyclicRecognition.zeroMeanL2SMulComm line 67
  7. theorem OAI.PolycyclicRecognition.zeroMeanL2_no_fixed line 71

    Source documentation

    Ergodicity removes every invariant vector from the zero-mean subspace.

    theorem zeroMeanL2_no_fixed
        {G X W : Type*} [Group G] [MeasurableSpace X] [MulAction G X]
        [MeasurableConstSMul G X] [NormedAddCommGroup W] [NormedSpace ℝ W]
        [CompleteSpace W] [SecondCountableTopology W]
        (μ : Measure X) [IsProbabilityMeasure μ] [ErgodicSMul G X μ]
        (v : ZeroMeanL2 (W := W) μ) (hfix : ∀ g : G, g • v = v) : v = 0 := by
    …

    Mentions: OAI.PolycyclicRecognition.ZeroMeanL2

  8. def OAI.PolycyclicRecognition.l2MeanSlope line 86

    Source documentation

    Averaging any L² cocycle gives a genuine height homomorphism.

    def l2MeanSlope (b : G → Lp W 2 μ) (hb : IsCocycle b) : G →* Multiplicative W where
    …

    Mentions: OAI.PolycyclicRecognition.IsCocycle

  9. def OAI.PolycyclicRecognition.centeredL2Cocycle line 97

    Source documentation

    Subtracting the actual averaged slope produces a zero-mean cocycle.

    def centeredL2Cocycle (b : G → Lp W 2 μ) (g : G) : ZeroMeanL2 (W := W) μ :=
    …

    Mentions: OAI.PolycyclicRecognition.ZeroMeanL2

  10. theorem OAI.PolycyclicRecognition.isCocycle_centeredL2 line 102
  11. theorem OAI.PolycyclicRecognition.continuous_centeredL2 line 116
  12. theorem OAI.PolycyclicRecognition.stationary_sublinear line 124

    Source documentation

    The fixed-measure stationary sublinear estimate, conditional only on the precise reduced-cohomology input for the constructed zero-mean representation. The analytic and algebraic hypotheses are verified on that representation.

    theorem stationary_sublinear
        {G X W : Type*} [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
        [TopologicalSpace X] [MeasurableSpace X] [BorelSpace X] [R1Space X]
        [MulAction G X] [ContinuousSMul G X]
        [NormedAddCommGroup W] [InnerProductSpace ℝ W] [CompleteSpace W]
        [SecondCountableTopology W]
        (μ : Measure X) [IsProbabilityMeasure μ] [ErgodicSMul G X μ]
        [μ.InnerRegularCompactLTTop]
        (hvan : ReducedCohomologyInput G (ZeroMeanL2 (W := W) μ))
    …

    Mentions: OAI.PolycyclicRecognition.ReducedCohomologyInput, OAI.PolycyclicRecognition.ZeroMeanL2