OAI/GroupTheory/Thompson/AnalyticLpCalculus.lean

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4 declarations, 0 contain sorry, 0 declared as axioms

Uniform estimates in the concrete Hilbert space

The restricted Lebesgue measure has mass one. Consequently, an almost-everywhere uniform bound on a representative gives the same bound on its L² norm. The derivative criterion below turns a quadratic norm remainder into a genuine derivative in any real normed space, including this Hilbert space.

  1. theorem OAI.ThompsonNonamenability.Analytic.intervalMeasure_univ line 24
  2. theorem OAI.ThompsonNonamenability.Analytic.norm_le_of_ae_bound line 28

    Source documentation

    A uniform bound on an almost-everywhere representative bounds the Hilbert norm.

    theorem norm_le_of_ae_bound (f : Hilbert) {C : ℝ} (hC : 0 ≤ C)
        (hbound : ∀ᵐ x ∂intervalMeasure, ‖f x‖ ≤ C) : ‖f‖ ≤ C := by
    …

    Mentions: OAI.ThompsonNonamenability.Analytic.Hilbert, OAI.ThompsonNonamenability.Analytic.intervalMeasure

  3. theorem OAI.ThompsonNonamenability.Analytic.norm_toLp_le line 38

    Source documentation

    The same estimate for an explicitly supplied square-integrable function.

    theorem norm_toLp_le {f : ℝ → Plane} (hf : MemLp f 2 intervalMeasure)
        {C : ℝ} (hC : 0 ≤ C) (hbound : ∀ᵐ x ∂intervalMeasure, ‖f x‖ ≤ C) :
        ‖hf.toLp f‖ ≤ C := by
    …

    Mentions: OAI.ThompsonNonamenability.Analytic.Plane, OAI.ThompsonNonamenability.Analytic.intervalMeasure

  4. theorem OAI.ThompsonNonamenability.Analytic.hasDerivAt_of_quadratic_remainder line 47

    Source documentation

    A quadratic norm remainder implies differentiability, without any pointwise choice of representatives in the codomain.

    theorem hasDerivAt_of_quadratic_remainder
        {E : Type uE} [NormedAddCommGroup E] [NormedSpace ℝ E]
        {f : ℝ → E} {f' : E} {x C : ℝ}
        (hrem : ∀ᶠ h in 𝓝 (0 : ℝ),
          ‖f (x + h) - f x - h • f'‖ ≤ C * |h| ^ 2) :
        HasDerivAt f f' x := by
    …