OAI/Analysis/KadisonSimilarity/Tracial/TracialUltrapowerCorners.lean

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The small-corner estimate passes from coordinate projections to the actual tracial ultrapower. Norm lifting and compression are constructed.

  1. theorem OAI.KadisonSimilarity.tracialUltrapower_corner_bound_of_projection_lift line 20

    Source documentation

    An actual lifted projection transfers every coordinate corner bound. No action of a null algebra sequence on the whole Hilbert ultrapower is asserted.

    theorem tracialUltrapower_corner_bound_of_projection_lift
        (T : τ.GNS →L[ℂ] τ.GNS) (p : ℕ →ᵇ A) (hp : ∀ i, IsStarProjection (p i))
        (e : Ultrapower τ h1 ω htr) (he : IsStarProjection e)
        (hpe : quotientHom τ h1 ω htr p = e)
        {ε : ℝ} (hε : 0 ≤ ε)
        (hcorner : ∀ i, ∀ z : CStarCorner (p i) (hp i),
          ‖commutator T (τ.gnsStarAlgHom (z : A))‖ ≤ ε * ‖z‖)
        (z : CStarCorner e he) :
        ‖commutator (tracialUltrapowerCompression τ h1 ω htr T)
          ((quotientTrace τ h1 ω htr).gnsStarAlgHom (z : Ultrapower τ h1 ω htr))‖ ≤ ε * ‖z‖ := by
    …

    Mentions: OAI.KadisonSimilarity.CStarCorner, OAI.KadisonSimilarity.commutator, OAI.KadisonSimilarity.tracialUltrapowerCompression