De Giorgi preiter of ball Sobolev on concentric Balls of ball Pos Part
DeGiorgi.deGiorgi_preiter_of_ballSobolev_on_concentricBalls_of_ballPosPart
Project documentation
PDE-facing De Giorgi pre-iteration wrapper on concentric balls. This theorem packages the bookkeeping step that combines: - a localized De Giorgi energy estimate at level θ, - a Sobolev/Hölder interpolation input for level λ, - and the Chebyshev bound already proved in this chapter. The local Sobolev/Hölder interpolation theorem is kept as an explicit...
Exact Lean statement
theorem deGiorgi_preiter_of_ballSobolev_on_concentricBalls_of_ballPosPart
{u η : E → ℝ} {x₀ : E} {r s θ lam Csob Cη : ℝ}
(hd : 0 < (d : ℝ))
(A : EllipticCoeff d (Metric.ball x₀ s))
(hr : 0 < r) (hrs : r < s)
(hθl : θ < lam)
(hCsob : 0 ≤ Csob)
(hsub : IsSubsolution A u)
(hu : MemW1pWitness 2 u (Metric.ball x₀ s))
(hwθ : MemW1pWitness 2 (positivePartSub u θ) (Metric.ball x₀ s))
(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)
(hCη : 0 ≤ Cη)
(hη_grad_bound : ∀ x, ‖fderiv ℝ η x‖ ≤ Cη)
(hη_sub_ball : tsupport η ⊆ Metric.ball x₀ s)
(hsob :
∫ x in Metric.ball x₀ r, |positivePartSub u lam x| ^ 2 ∂volume ≤
Csob * (∫ x in Metric.ball x₀ r, ‖hwθ.weakGrad x‖ ^ 2 ∂volume) *
((volume.restrict (Metric.ball x₀ s)).real {x | lam < u x}) ^ (2 / (d : ℝ))) :
∫ x in Metric.ball x₀ r, |positivePartSub u lam x| ^ 2 ∂volume ≤
Csob * (4 * ellipticityRatio A * Cη ^ 2) *
((((lam - θ) ^ 2)⁻¹ *
∫ x in Metric.ball x₀ s, |positivePartSub u θ x| ^ 2 ∂volume) ^ (2 / (d : ℝ))) *
∫ x in Metric.ball x₀ s, |positivePartSub u θ x| ^ 2 ∂volumeFormal artifact
Lean source
theorem deGiorgi_preiter_of_ballSobolev_on_concentricBalls_of_ballPosPart {u η : E → ℝ} {x₀ : E} {r s θ lam Csob Cη : ℝ} (hd : 0 < (d : ℝ)) (A : EllipticCoeff d (Metric.ball x₀ s)) (hr : 0 < r) (hrs : r < s) (hθl : θ < lam) (hCsob : 0 ≤ Csob) (hsub : IsSubsolution A u) (hu : MemW1pWitness 2 u (Metric.ball x₀ s)) (hwθ : MemW1pWitness 2 (positivePartSub u θ) (Metric.ball x₀ s)) (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) (hCη : 0 ≤ Cη) (hη_grad_bound : ∀ x, ‖fderiv ℝ η x‖ ≤ Cη) (hη_sub_ball : tsupport η ⊆ Metric.ball x₀ s) (hsob : ∫ x in Metric.ball x₀ r, |positivePartSub u lam x| ^ 2 ∂volume ≤ Csob * (∫ x in Metric.ball x₀ r, ‖hwθ.weakGrad x‖ ^ 2 ∂volume) * ((volume.restrict (Metric.ball x₀ s)).real {x | lam < u x}) ^ (2 / (d : ℝ))) : ∫ x in Metric.ball x₀ r, |positivePartSub u lam x| ^ 2 ∂volume ≤ Csob * (4 * ellipticityRatio A * Cη ^ 2) * ((((lam - θ) ^ 2)⁻¹ * ∫ x in Metric.ball x₀ s, |positivePartSub u θ x| ^ 2 ∂volume) ^ (2 / (d : ℝ))) * ∫ x in Metric.ball x₀ s, |positivePartSub u θ x| ^ 2 ∂volume := by haveI : IsFiniteMeasure (volume.restrict (Metric.ball x₀ s)) := by rw [isFiniteMeasure_restrict] exact measure_ball_lt_top.ne have hθ_int : Integrable (fun x => |positivePartSub u θ x| ^ 2) (volume.restrict (Metric.ball x₀ s)) := by simpa [pow_two] using hwθ.memLp.integrable_sq have hIθ_nonneg : 0 ≤ ∫ x in Metric.ball x₀ s, |positivePartSub u θ x| ^ 2 ∂volume := by refine integral_nonneg ?_ intro x positivity have henergy : ∫ x in Metric.ball x₀ r, ‖hwθ.weakGrad x‖ ^ 2 ∂volume ≤ (4 * ellipticityRatio A * Cη ^ 2) * ∫ x in Metric.ball x₀ s, |positivePartSub u θ x| ^ 2 ∂volume := by simpa using deGiorgi_energy_estimate_on_concentricBalls_of_ballPosPart A hr hrs hsub hu hwθ hη hη_nonneg hη_eq_one hη_bound hCη hη_grad_bound hη_sub_ball exact deGiorgi_preiter_of_energy (μ := volume.restrict (Metric.ball x₀ s)) hd hθl hCsob (by have hRatio_nonneg : 0 ≤ ellipticityRatio A := A.ellipticityRatio_nonneg have hCη_sq_nonneg : 0 ≤ Cη ^ 2 := sq_nonneg Cη nlinarith) hIθ_nonneg hθ_int hsob henergy (by rfl)- Project
- DeGiorgi
- License
- Apache-2.0
- Commit
- 4c1b3077d378
- Source
- DeGiorgi/DeGiorgiIteration/PreIteration.lean:47-103
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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.