De Giorgi cutoff Sobolev on concentric Balls of ball Pos Part
DeGiorgi.deGiorgi_cutoffSobolev_on_concentricBalls_of_ballPosPart
Plain-language statement
Sobolev/Hölder step for De Giorgi pre-iteration on concentric balls. The argument passes through a zero-trace cutoff witness for η² (u - θ)₊. The originally intended statement with only the bare θ-truncation gradient on the right-hand side is false, e.g. for constant superlevel functions. The proof here records the actual Chapter 05 mechanism: 1. buil...
Exact Lean statement
theorem deGiorgi_cutoffSobolev_on_concentricBalls_of_ballPosPart
{u η : E → ℝ} {x₀ : E} {r s θ lam : ℝ}
(hd : 2 < (d : ℝ))
(hr : 0 < r) (hrs : r < s)
(hu : MemW1pWitness 2 u (Metric.ball x₀ s))
(hwθ : MemW1pWitness 2 (positivePartSub u θ) (Metric.ball x₀ s))
(hθl : θ < lam)
(hη : ContDiff ℝ (⊤ : ℕ∞) η)
(_hη_nonneg : ∀ x, 0 ≤ η x)
(hη_eq_one : ∀ x ∈ Metric.ball x₀ r, η x = 1)
(hη_bound : ∀ x, |η x| ≤ 1)
(hη_sub_ball : tsupport η ⊆ Metric.ball x₀ s) :
∃ hwηθ : MemW1pWitness 2 (deGiorgiCutoffTestGeneral η u θ) (Metric.ball x₀ s),
∫ x in Metric.ball x₀ r, |positivePartSub u lam x| ^ 2 ∂volume ≤
(C_gns d 2) ^ 2 *
(∫ x in Metric.ball x₀ s, ‖hwηθ.weakGrad x‖ ^ 2 ∂volume) *
((volume.restrict (Metric.ball x₀ s)).real {x | lam < u x}) ^ (2 / (d : ℝ))Formal artifact
Lean source
theorem deGiorgi_cutoffSobolev_on_concentricBalls_of_ballPosPart {u η : E → ℝ} {x₀ : E} {r s θ lam : ℝ} (hd : 2 < (d : ℝ)) (hr : 0 < r) (hrs : r < s) (hu : MemW1pWitness 2 u (Metric.ball x₀ s)) (hwθ : MemW1pWitness 2 (positivePartSub u θ) (Metric.ball x₀ s)) (hθl : θ < lam) (hη : ContDiff ℝ (⊤ : ℕ∞) η) (_hη_nonneg : ∀ x, 0 ≤ η x) (hη_eq_one : ∀ x ∈ Metric.ball x₀ r, η x = 1) (hη_bound : ∀ x, |η x| ≤ 1) (hη_sub_ball : tsupport η ⊆ Metric.ball x₀ s) : ∃ hwηθ : MemW1pWitness 2 (deGiorgiCutoffTestGeneral η u θ) (Metric.ball x₀ s), ∫ x in Metric.ball x₀ r, |positivePartSub u lam x| ^ 2 ∂volume ≤ (C_gns d 2) ^ 2 * (∫ x in Metric.ball x₀ s, ‖hwηθ.weakGrad x‖ ^ 2 ∂volume) * ((volume.restrict (Metric.ball x₀ s)).real {x | lam < u x}) ^ (2 / (d : ℝ)) := by have hs : 0 < s := lt_trans hr hrs let v : E → ℝ := deGiorgiCutoffTestGeneral η u θ haveI : IsFiniteMeasure (volume.restrict (Metric.ball x₀ s)) := by rw [isFiniteMeasure_restrict] exact measure_ball_lt_top.ne have hη_comp : HasCompactSupport η := hasCompactSupport_of_tsupport_subset_ball hη_sub_ball obtain ⟨Cη, hCη, hη_grad_bound⟩ := exists_fderiv_bound_of_contDiff_hasCompactSupport hη hη_comp have hvW01 : MemW01p 2 (deGiorgiCutoffTestGeneral η u θ) (Metric.ball x₀ s) := deGiorgiCutoffTest_memW01p_of_truncWitness isOpen_ball hwθ hη (by norm_num) hCη hη_bound hη_grad_bound hη_comp hη_sub_ball obtain ⟨hwηθ_real, hSob''⟩ := deGiorgi_cutoffSobolev_prepare (d := d) hd hs hu hη hη_bound hη_sub_ball hvW01 let hwηθ : MemW1pWitness 2 v (Metric.ball x₀ s) := { memLp := by simpa [v] using hwηθ_real.memLp weakGrad := hwηθ_real.weakGrad weakGrad_component_memLp := by simpa using hwηθ_real.weakGrad_component_memLp isWeakGrad := by simpa [v] using hwηθ_real.isWeakGrad } refine ⟨hwηθ, ?_⟩ simpa [v, hwηθ] using deGiorgi_cutoffSobolev_superlevelStep (d := d) hd hr hrs hu hwθ hθl hη_eq_one hwηθ_real hSob''- Project
- DeGiorgi
- License
- Apache-2.0
- Commit
- 4c1b3077d378
- Source
- DeGiorgi/DeGiorgiIteration/PreIteration.lean:664-707
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Related declarations
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Plain-language statement
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Source project: DeGiorgi
Person-level attribution pending.
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Person-level attribution pending.
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Source project: DeGiorgi
Person-level attribution pending.