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.
- theorem
OAI.KadisonSimilarity.FiniteFactorPresentation.exists_small_source_compressionline 39Source 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 …