De Giorgi Cutoff Test mem W01p of pos Part Approx
DeGiorgi.deGiorgiCutoffTest_memW01p_of_posPartApprox
Project documentation
Concrete cutoff admissibility theorem using the Chapter 02 positive-part witness constructor and an explicit smooth-approximation package for u - k.
Exact Lean statement
theorem deGiorgiCutoffTest_memW01p_of_posPartApprox
{Ω : Set E} [IsFiniteMeasure (volume.restrict Ω)]
(hΩ : IsOpen Ω)
{u η : E → ℝ}
(hw : MemW1pWitness 2 u Ω)
(hη : ContDiff ℝ (⊤ : ℕ∞) η)
{C₀ C₁ : ℝ}
(hC₀ : 0 ≤ C₀) (hC₁ : 0 ≤ C₁)
(hη_bound : ∀ x, |η x| ≤ C₀)
(hη_grad_bound : ∀ x, ‖fderiv ℝ η x‖ ≤ C₁)
(hη_comp : HasCompactSupport η)
(hη_sub : tsupport η ⊆ Ω)
(k : ℝ)
(happroxShift :
∃ ψ : ℕ → E → ℝ,
(∀ n, ContDiff ℝ 1 (ψ n)) ∧
(∀ n, HasCompactSupport (ψ n)) ∧
Tendsto (fun n => eLpNorm (fun x => ψ n x - (u x - k)) 2 (volume.restrict Ω))
atTop (nhds 0) ∧
(∀ i : Fin d,
Tendsto (fun n => eLpNorm (fun x =>
(fderiv ℝ (ψ n) x) (EuclideanSpace.single i 1) - hw.weakGrad x i)
2 (volume.restrict Ω))
atTop (nhds 0))) :
MemW01p 2 (deGiorgiCutoffTestGeneral η u k) ΩFormal artifact
Lean source
theorem deGiorgiCutoffTest_memW01p_of_posPartApprox {Ω : Set E} [IsFiniteMeasure (volume.restrict Ω)] (hΩ : IsOpen Ω) {u η : E → ℝ} (hw : MemW1pWitness 2 u Ω) (hη : ContDiff ℝ (⊤ : ℕ∞) η) {C₀ C₁ : ℝ} (hC₀ : 0 ≤ C₀) (hC₁ : 0 ≤ C₁) (hη_bound : ∀ x, |η x| ≤ C₀) (hη_grad_bound : ∀ x, ‖fderiv ℝ η x‖ ≤ C₁) (hη_comp : HasCompactSupport η) (hη_sub : tsupport η ⊆ Ω) (k : ℝ) (happroxShift : ∃ ψ : ℕ → E → ℝ, (∀ n, ContDiff ℝ 1 (ψ n)) ∧ (∀ n, HasCompactSupport (ψ n)) ∧ Tendsto (fun n => eLpNorm (fun x => ψ n x - (u x - k)) 2 (volume.restrict Ω)) atTop (nhds 0) ∧ (∀ i : Fin d, Tendsto (fun n => eLpNorm (fun x => (fderiv ℝ (ψ n) x) (EuclideanSpace.single i 1) - hw.weakGrad x i) 2 (volume.restrict Ω)) atTop (nhds 0))) : MemW01p 2 (deGiorgiCutoffTestGeneral η u k) Ω := by let hw_trunc : MemW1pWitness 2 (positivePartSub u k) Ω := positivePartSub_memW1pWitness hΩ hw k happroxShift exact deGiorgiCutoffTest_memW01p_of_truncWitness hΩ hw_trunc hη hC₀ hC₁ hη_bound hη_grad_bound hη_comp hη_sub- Project
- DeGiorgi
- License
- Apache-2.0
- Commit
- 4c1b3077d378
- Source
- DeGiorgi/DeGiorgiIteration/CutoffAdmissibility.lean:164-193
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Related declarations
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.
Source project: DeGiorgi
Person-level attribution pending.
E Lp Norm pi le sum component
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.
Source project: DeGiorgi
Person-level attribution pending.
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) < ∞.
Source project: DeGiorgi
Person-level attribution pending.