OAI/Analysis/KadisonKastler/TraceProjectionLimits.lean

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Projections obtained as bounded tracial limits

  1. theorem OAI.KadisonKastler.FiniteVectorTrace.projection_limit line 20

    Source documentation

    Selfadjoint contractive two-Cauchy sequences with vanishing idempotency defect converge to a projection in the original algebra.

    theorem FiniteVectorTrace.projection_limit
        {τ : FaithfulTracialState (Algebra M)} (hτ : FiniteVectorTrace τ)
        (x : ℕ → Algebra M) (hx : ∀ j, ‖x j‖ ≤ 1)
        (hsa : ∀ j, IsSelfAdjoint (x j))
        (hCauchy : ∀ ε > 0, ∃ N : ℕ, ∀ m ≥ N, ∀ n ≥ N,
          traceTwoNorm τ (x m - x n) < ε)
        (hdefect : Tendsto (fun j => traceTwoNorm τ (x j * x j - x j)) atTop (𝓝 0)) :
        ∃ e : Algebra M, IsStarProjection e ∧ ‖e‖ ≤ 1 ∧
          (∀ ξ, Tendsto (fun j => (x j : H →L[ℂ] H) ξ) atTop
            (𝓝 ((e : H →L[ℂ] H) ξ))) ∧
          Tendsto (fun j => traceTwoNorm τ (x j - e)) atTop (𝓝 0) := by
    …

    Mentions: OAI.KadisonKastler.FaithfulTracialState, OAI.KadisonKastler.Algebra, OAI.KadisonKastler.FiniteVectorTrace, OAI.KadisonKastler.traceTwoNorm