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Project-declaredLean 4.29.0-rc6 · mathlib@5c8398df5281

Aestrongly Measurable divergence RHSIntegrand Of Field

DeGiorgi.aestronglyMeasurable_divergenceRHSIntegrandOfField

Plain-language statement

The divergence-form RHS integrand is a.e. strongly measurable on Ω.

Exact Lean statement

theorem aestronglyMeasurable_divergenceRHSIntegrandOfField
    {Ω : Set E} {F : E → E} (hF : MemLp F 2 (volume.restrict Ω))
    {v : E → ℝ} (hv : MemW1pWitness 2 v Ω) :
    AEStronglyMeasurable (divergenceRHSIntegrandOfField F hv) (volume.restrict Ω)

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
theorem aestronglyMeasurable_divergenceRHSIntegrandOfField    {Ω : Set E} {F : E  E} (hF : MemLp F 2 (volume.restrict Ω))    {v : E  } (hv : MemW1pWitness 2 v Ω) :    AEStronglyMeasurable (divergenceRHSIntegrandOfField F hv) (volume.restrict Ω) := by  have hF_ofLp_cont : Continuous (fun y : E => (WithLp.ofLp y : Fin d  )) := by    simpa using (PiLp.continuous_ofLp 2 (fun _ : Fin d => ))  have hF_ofLp :      AEStronglyMeasurable (fun x => (WithLp.ofLp (F x) : Fin d  )) (volume.restrict Ω) :=    hF_ofLp_cont.comp_aestronglyMeasurable hF.aestronglyMeasurable  have hsum :      AEMeasurable        (∑ i : Fin d, fun x => F x i * hv.weakGrad x i)        (volume.restrict Ω) := by    refine Finset.aemeasurable_sum (s := (Finset.univ : Finset (Fin d)))      (f := fun i x => F x i * hv.weakGrad x i) ?_    intro i _hi    have hFi : AEMeasurable (fun x => F x i) (volume.restrict Ω) := by      simpa using        (Continuous.comp_aestronglyMeasurable (continuous_apply i) hF_ofLp).aemeasurable    exact hFi.mul (hv.weakGrad_component_memLp i).aemeasurable  have hscalar :  a b : , ⟪a, b⟫_ = a * b := by    intro a b    simpa using (RCLike.inner_apply' a b)  refine hsum.aestronglyMeasurable.congr ?_  filter_upwards with x  simp [divergenceRHSIntegrandOfField, PiLp.inner_apply, hscalar]
Project
DeGiorgi
License
Apache-2.0
Commit
4c1b3077d378
Source
DeGiorgi/WeakFormulation/BilinearForm.lean:347-372

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Related declarations

Project-declaredLean 4.29.0-rc6

Ae eq of tendsto e Lp Norm sub

BareFunction.ae_eq_of_tendsto_eLpNorm_sub

Plain-language statement

Lp limit uniqueness: if f_n → g₁ and f_n → g₂ in eLpNorm, then g₁ =ᵐ g₂.

partial differential equationsregularity theoryanalysis

Source project: DeGiorgi

Person-level attribution pending.

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Project-declaredLean 4.29.0-rc6

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BareFunction.eLpNorm_pi_le_sum_component

Plain-language statement

Vector eLpNorm ≤ sum of component eLpNorms for Pi-valued functions. Uses eLpNorm_mono_real for the pointwise bound together with eLpNorm_sum_le for ℝ-valued functions, avoiding Pi instance synthesis.

partial differential equationsregularity theoryanalysis

Source project: DeGiorgi

Person-level attribution pending.

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Project-declaredLean 4.29.0-rc6

Mem Lp of tendsto e Lp Norm

BareFunction.memLp_of_tendsto_eLpNorm

Plain-language statement

If f n → g in eLpNorm and each f n ∈ Lp, then g ∈ Lp, provided g is AEStronglyMeasurable. Avoids the Lp type entirely. The key observation: eLpNorm (f n - g) → 0 means eLpNorm (f N - g) < 1 for some N. Then eLpNorm g ≤ eLpNorm (f N - g) + eLpNorm (f N) < ∞.

partial differential equationsregularity theoryanalysis

Source project: DeGiorgi

Person-level attribution pending.

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