OAI/Geometry/EinsteinFour/ScalarLpNormVariation.lean

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6 declarations, 0 contain sorry, 0 declared as axioms

The squared Lp norm at a normalized function has the expected first variation, including for sign-changing or merely Lp representatives.

  1. theorem OAI.PositiveEinsteinFour.Geometry.scalarLp_norm_eq_moment line 19

    Source documentation

    The ordinary real Lp norm as an integral of the actual representative.

    theorem scalarLp_norm_eq_moment {p : ℝ} [Fact (1 ≤ ENNReal.ofReal p)] (hp : 0 < p)
        (f : Lp ℝ (ENNReal.ofReal p) μ) :
        ‖f‖ = (∫ x, |f x| ^ p ∂μ) ^ p⁻¹ := by
    …
  2. theorem OAI.PositiveEinsteinFour.Geometry.scalarLp_moment_eq_norm_rpow line 27
  3. theorem OAI.PositiveEinsteinFour.Geometry.scalarLp_norm_sq_eq_moment line 33
  4. theorem OAI.PositiveEinsteinFour.Geometry.scalarLp_add_smul_moment line 40
  5. theorem OAI.PositiveEinsteinFour.Geometry.scalarLpNormSq_hasDerivAt line 52

    Source documentation

    At Lp norm one, the squared norm differentiates to twice the nonlinear pairing against a bounded measurable direction.

    theorem scalarLpNormSq_hasDerivAt {p : ℝ} [Fact (1 ≤ ENNReal.ofReal p)]
        (hp : 2 < p) (f b : Lp ℝ (ENNReal.ofReal p) μ) (hf : ‖f‖ = 1)
        {B : ℝ} (hB : 0 ≤ B) (hb : ∀ᵐ x ∂μ, |b x| ≤ B) :
        HasDerivAt (fun t : ℝ => ‖f + t • b‖ ^ 2)
          (2 * ∫ x, |f x| ^ (p - 2) * f x * b x ∂μ) 0 := by
    …
  6. theorem OAI.PositiveEinsteinFour.Geometry.scalarLpNormSq_hasDerivAt_continuous line 74

    Source documentation

    A continuous representative of the direction is sufficient; no regularity or pointwise sign is required of the normalized Lp function.

    theorem scalarLpNormSq_hasDerivAt_continuous [TopologicalSpace X]
        [OpensMeasurableSpace X] [CompactSpace X] {p : ℝ}
        [Fact (1 ≤ ENNReal.ofReal p)] (hp : 2 < p)
        (f b : Lp ℝ (ENNReal.ofReal p) μ) (hf : ‖f‖ = 1)
        (v : C(X, ℝ)) (hb : (b : X → ℝ) =ᵐ[μ] v) :
        HasDerivAt (fun t : ℝ => ‖f + t • b‖ ^ 2)
          (2 * ∫ x, |f x| ^ (p - 2) * f x * v x ∂μ) 0 := by
    …