OAI/Analysis/KadisonSimilarity/Tracial/SourceLocalQuantization.lean

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Relative local quantization for the actual source in the constructed finite-factor presentation. Every small projection lies in that source.

  1. theorem OAI.KadisonSimilarity.FiniteFactorPresentation.exists_small_source_compression line 39

    Source documentation

    Centered ambient coefficients admit a nonzero, arbitrarily small source projection on which all compressions have arbitrarily small trace norm.

    theorem exists_small_source_compression {I : Type*} [Fintype I]
        (x : I → F.N.toStarSubalgebra) (hx : ∀ i, F.representation.trace (x i) = 0)
        {δ η : ℝ} (hδ : 0 < δ) (hη : 0 < η) :
        ∃ q : (FiniteMatrixStage.generatedVonNeumann F.source.stages).toStarSubalgebra,
          IsStarProjection q ∧ q ≠ 0 ∧
          (F.representation.trace
            (coordinateInclusion (FiniteMatrixStage.generatedVonNeumann_le F.source.stages) q)).re < η ∧
          ∀ i, ‖(vectorPositiveFunctional F.N F.representation.vector).toPreGNS
            (coordinateInclusion (FiniteMatrixStage.generatedVonNeumann_le F.source.stages) q * x i *
              coordinateInclusion (FiniteMatrixStage.generatedVonNeumann_le F.source.stages) q)‖ ^ 2 <
            δ * (F.representation.trace
              (coordinateInclusion (FiniteMatrixStage.generatedVonNeumann_le F.source.stages) q)).re := by
    …

    Mentions: OAI.KadisonSimilarity.vectorPositiveFunctional