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LeanPool.CaffarelliKohnNirenberg.Foundation.Parabolic.Integration.Scaling

Scaling, translation, and radius monotonicity #

The declarations here keep the geometric maps from Basic.lean and expose the change-of-variables statements needed for scale-invariant quantities. In particular, no source-facing quantity is introduced in this module.

A parabolic rescaling with a scalar power weight.

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    The image of a centred cylinder under a positive rescaling and translation.

    Bochner integration on a parabolic cylinder changes by the homogeneous factor a⁻⁵.

    The corresponding nonnegative cylinder lintegral has homogeneous factor a⁻⁵.

    The velocity-weighted cylinder power integral changes by a^(p-5).

    A single spatial time slice changes by the spatial factor a⁻³.

    theorem CKN.Foundation.Parabolic.Integration.timeSlice_setIntegral_rescaled_power {a : ℝ} (ha : 0 < a) (x : Vec3) (t r s p : ℝ) (u : ParabolicPoint → ℝ) :
    MeasureTheory.IntegrableOn (fun (y : Vec3) => |u (parabolicTranslate x t (parabolicScale a (y, s)))| ^ p) (vec3Ball 0 r) MeasureTheory.volume → MeasureTheory.IntegrableOn (fun (y : Vec3) => |u (y, t + a ^ 2 * s)| ^ p) (vec3Ball x (a * r)) MeasureTheory.volume → ∫ (y : Vec3) in vec3Ball 0 r, |a * u (parabolicTranslate x t (parabolicScale a (y, s)))| ^ p = a ^ (p - 3) * ∫ (y : Vec3) in vec3Ball x (a * r), |u (y, t + a ^ 2 * s)| ^ p

    A velocity-weighted time-slice power integral changes by a^(p-3).

    theorem CKN.Foundation.Parabolic.Integration.spatial_setIntegral_comp_smul {a : ℝ} (ha : 0 < a) (x : Vec3) (r : ℝ) (f : Vec3 → ℝ) :
    ∫ (y : Vec3) in vec3Ball x r, f (a • y) = (a ^ Module.finrank ℝ Vec3)⁻¹ • ∫ (y : Vec3) in a • vec3Ball x r, f y

    Spatial change of variables under a positive dilation.

    theorem CKN.Foundation.Parabolic.Integration.time_setIntegral_comp_smul {a : ℝ} (ha : 0 < a) (s₁ s₂ : ℝ) (f : ℝ → ℝ) :
    ∫ (s : ℝ) in Set.Ioc s₁ s₂, f (a • s) = (a ^ Module.finrank ℝ ℝ)⁻¹ • ∫ (s : ℝ) in a • Set.Ioc s₁ s₂, f s

    One-dimensional time change of variables under a positive dilation.

    theorem CKN.Foundation.Parabolic.Integration.spatial_setIntegral_rescaled_power {a : ℝ} (ha : 0 < a) (x : Vec3) (r p c : ℝ) (u : Vec3 → ℝ) :
    ∫ (y : Vec3) in vec3Ball x r, |c * u (a • y)| ^ p = (a ^ Module.finrank ℝ Vec3)⁻¹ * ∫ (y : Vec3) in a • vec3Ball x r, |c * u y| ^ p

    Spatial power integrals transform with an arbitrary constant weight.

    theorem CKN.Foundation.Parabolic.Integration.time_setIntegral_rescaled_power {a : ℝ} (ha : 0 < a) (s₁ s₂ p c : ℝ) (u : ℝ → ℝ) :
    ∫ (s : ℝ) in Set.Ioc s₁ s₂, |c * u (a • s)| ^ p = (a ^ Module.finrank ℝ ℝ)⁻¹ * ∫ (s : ℝ) in a • Set.Ioc s₁ s₂, |c * u s| ^ p

    Time-slice power integrals transform with an arbitrary constant weight.

    Translation preserves the volume of a parabolic cylinder.

    Essential supremum of a time-slice energy over the cylinder time interval.

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      theorem CKN.Foundation.Parabolic.Integration.timeSliceEnergyEssSup_comp_parabolicRescale {a : ℝ} (ha : 0 < a) (x : Vec3) (t r : ℝ) (g : ParabolicPoint → ℝ) (hsource : Filter.IsBoundedUnder (fun (x1 x2 : ENNReal) => x1 ≤ x2) (MeasureTheory.ae (MeasureTheory.volume.restrict (Set.Ioc (-r ^ 2) 0))) fun (s : ℝ) => ∫⁻ (y : Vec3) in vec3Ball x (a * r), ‖g (y, t + a ^ 2 * s)‖ₑ ^ 2) (htarget : Filter.IsBoundedUnder (fun (x1 x2 : ENNReal) => x1 ≤ x2) (MeasureTheory.ae (MeasureTheory.volume.restrict (Set.Ioc (t - (a * r) ^ 2) t))) fun (s : ℝ) => ∫⁻ (y : Vec3) in vec3Ball x (a * r), ‖g (y, s)‖ₑ ^ 2) :

      The time-slice energy essential supremum changes by the spatial factor a⁻³.

      theorem CKN.Foundation.Parabolic.Integration.essSup_mono_measure_and_ae {α : Type u_1} [MeasurableSpace α] {μ ν : MeasureTheory.Measure α} {f g : α → ENNReal} (hμν : μ ≤ ν) (hfg : f ≤ᵐ[μ] g) :
      essSup f μ ≤ essSup g ν

      Essential suprema increase when the measure and the integrand both increase.

      theorem CKN.Foundation.Parabolic.Integration.time_interval_mono_radius {t r₁ r₂ : ℝ} (hr₁ : 0 ≤ r₁) (hrr : r₁ ≤ r₂) :
      Set.Ioc (t - r₁ ^ 2) t ⊆ Set.Ioc (t - r₂ ^ 2) t

      The time interval for a smaller nonnegative radius is contained in the larger one.

      theorem CKN.Foundation.Parabolic.Integration.timeSliceEnergyEssSup_mono_radius {x : Vec3} {t r₁ r₂ : ℝ} (hr₁ : 0 ≤ r₁) (hrr : r₁ ≤ r₂) (g : ParabolicPoint → ℝ) :

      The time-slice L² energy essential supremum is monotone in the radius.

      theorem CKN.Foundation.Parabolic.Integration.timeSliceEnergyEssSup_div_radius_le {x : Vec3} {t r₁ r₂ : ℝ} (hr₁ : 0 < r₁) (hrr : r₁ ≤ r₂) (g : ParabolicPoint → ℝ) :

      The radius-normalized time-slice essential supremum has the standard comparison.