OAI/Analysis/KadisonKastler/QuadraticMultiplicationCorrection.lean

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Quantitative quadratic correction of an associative multiplication

  1. theorem OAI.KadisonKastler.quadratic_correction_half_bound line 14
  2. theorem OAI.KadisonKastler.quadratic_multiplication_half_step line 23

    Source documentation

    A cochain with unit complete bound and quadratic coboundary error gives an invertible, star-preserving correction which halves the error.

    theorem quadratic_multiplication_half_step
        (m : A →ₗ[ℂ] A →ₗ[ℂ] A)
        (hm : ∀ x y z, m (m x y) z = m x (m y z))
        (hmstar : ∀ x y, star (m x y) = m (star y) (star x))
        {q : ℝ} (hq : 0 ≤ q) (hq1 : q ≤ 1 / 11)
        (hbound : HaagerupBound (m - LinearMap.mul ℂ A) q)
        (D : A →ₗ[ℂ] A) (hD : CompletelyBoundedBy D q)
        (hDstar : ∀ x, D (star x) = star (D x))
        (hres : HaagerupBound (m - LinearMap.mul ℂ A - linearCoboundary D) (2 * q ^ 2)) :
        ∃ L : A ≃ₗ[ℂ] A,
          L.toLinearMap = LinearMap.id + D ∧
          (∀ x, L (star x) = star (L x)) ∧
    …

    Mentions: OAI.KadisonKastler.HaagerupBound, OAI.KadisonKastler.CompletelyBoundedBy, OAI.KadisonKastler.linearCoboundary