Supersolution ae closeout inv
DeGiorgi.supersolution_ae_closeout_inv
Plain-language statement
Closeout: pass from iterated L^{pₙ}(B_{rₙ}) bounds to an a.e. L^∞ bound on u⁻¹ over B_{1/2}. Since rₙ > 1/2 for all n and pₙ → ∞, the L^{pₙ} norms converge to the L^∞ norm. The uniform bound from the iteration + geometric majorant gives the pointwise bound.
Exact Lean statement
theorem supersolution_ae_closeout_inv
(hd : 2 < (d : ℝ))
(A : NormalizedEllipticCoeff d (Metric.ball (0 : E) 1))
{u : E → ℝ} {p₀ : ℝ} (hp₀ : 0 < p₀)
(hu_pos : ∀ x ∈ Metric.ball (0 : E) 1, 0 < u x)
(hsuper : IsSupersolution A.1 u)
(hpInt :
IntegrableOn (fun x => |(u x)⁻¹| ^ p₀)
(Metric.ball (0 : E) 1) volume) :
∀ᵐ x ∂(volume.restrict (Metric.ball (0 : E) (1 / 2 : ℝ))),
|(u x)⁻¹| ^ p₀ ≤
C_weakHarnack0 d * (A.1.Λ * p₀ ^ 2 + 1) ^ ((d : ℝ) / 2) *
∫ x in Metric.ball (0 : E) 1, |(u x)⁻¹| ^ p₀ ∂volumeFormal artifact
Lean source
theorem supersolution_ae_closeout_inv (hd : 2 < (d : ℝ)) (A : NormalizedEllipticCoeff d (Metric.ball (0 : E) 1)) {u : E → ℝ} {p₀ : ℝ} (hp₀ : 0 < p₀) (hu_pos : ∀ x ∈ Metric.ball (0 : E) 1, 0 < u x) (hsuper : IsSupersolution A.1 u) (hpInt : IntegrableOn (fun x => |(u x)⁻¹| ^ p₀) (Metric.ball (0 : E) 1) volume) : ∀ᵐ x ∂(volume.restrict (Metric.ball (0 : E) (1 / 2 : ℝ))), |(u x)⁻¹| ^ p₀ ≤ C_weakHarnack0 d * (A.1.Λ * p₀ ^ 2 + 1) ^ ((d : ℝ) / 2) * ∫ x in Metric.ball (0 : E) 1, |(u x)⁻¹| ^ p₀ ∂volume := by let Bhalf : Set E := Metric.ball (0 : E) (1 / 2 : ℝ) let μ : Measure E := volume.restrict Bhalf let f : E → ℝ := fun x => |(u x)⁻¹| let g : E → ℝ := fun x => f x ^ (p₀ / 2) let K : ℝ := (C_weakHarnack0 d * (A.1.Λ * p₀ ^ 2 + 1) ^ ((d : ℝ) / 2) * ∫ x in Metric.ball (0 : E) 1, |(u x)⁻¹| ^ p₀ ∂volume) ^ (1 / 2 : ℝ) haveI : IsFiniteMeasure μ := by dsimp [μ, Bhalf] rw [isFiniteMeasure_restrict] exact measure_ne_top_of_subset Metric.ball_subset_closedBall (isCompact_closedBall (0 : E) (1 / 2 : ℝ)).measure_lt_top.ne have hK_nonneg : 0 ≤ K := by dsimp [K] exact Real.rpow_nonneg (supersolutionInvBoundPow_nonneg (d := d) A) _ have hiter : ∀ n, IntegrableOn (fun x => |(u x)⁻¹| ^ moserExponentSeq d p₀ n) (Metric.ball (0 : E) (moserRadius n)) volume ∧ superIterNormInv (d := d) (u := u) p₀ n ≤ ((C_weakHarnack0 d * (A.1.Λ * p₀ ^ 2 + 1) ^ ((d : ℝ) / 2)) ^ (1 / p₀)) * superIterNormInv (d := d) (u := u) p₀ 0 := by intro n have hraw := supersolution_iteration_inverse (d := d) hd A hp₀ hu_pos hsuper hpInt n have hgeom := supersolution_geometric_majorant_inv (d := d) hd A hp₀ n refine ⟨hraw.1, ?_⟩ calc superIterNormInv (d := d) (u := u) p₀ n ≤ (∏ i ∈ Finset.range n, superStepConstInv (d := d) A p₀ i) * superIterNormInv (d := d) (u := u) p₀ 0 := hraw.2 _ ≤ ((C_weakHarnack0 d * (A.1.Λ * p₀ ^ 2 + 1) ^ ((d : ℝ) / 2)) ^ (1 / p₀)) * superIterNormInv (d := d) (u := u) p₀ 0 := by exact mul_le_mul_of_nonneg_right hgeom (by dsimp [superIterNormInv] exact Real.rpow_nonneg (integral_nonneg fun x => by positivity) _) have hbound_all : ∀ m : ℕ, ∀ᵐ x ∂μ, g x < K + 1 / (m + 1 : ℝ) := by intro m have hzero : μ.real {x | K + 1 / (m + 1 : ℝ) ≤ g x} = 0 := by refine supersolution_closeout_superlevel_null (d := d) hd A (u := u) hp₀ hiter ?_ dsimp [K] have hfrac_pos : 0 < 1 / (m + 1 : ℝ) := by positivity linarith rw [ae_iff] simpa [μ, Bhalf, g, K, not_lt] using (measureReal_eq_zero_iff (μ := μ) (s := {x | K + 1 / (m + 1 : ℝ) ≤ g x}) (measure_ne_top μ {x | K + 1 / (m + 1 : ℝ) ≤ g x})).1 hzero have hbound_ae : ∀ᵐ x ∂μ, ∀ m : ℕ, g x < K + 1 / (m + 1 : ℝ) := by exact ae_all_iff.2 hbound_all filter_upwards [hbound_ae] with x hx have hfx_nonneg : 0 ≤ f x := by dsimp [f] exact abs_nonneg ((u x)⁻¹) have hgx_nonneg : 0 ≤ g x := by dsimp [g] exact Real.rpow_nonneg hfx_nonneg _ have hgx_le : g x ≤ K := by by_contra hgx_gt have hgap_pos : 0 < g x - K := by linarith obtain ⟨m, hm⟩ := exists_nat_one_div_lt hgap_pos have hlt : K + 1 / (m + 1 : ℝ) < g x := by linarith linarith [hx m] have hgpow : g x ^ (2 : ℝ) ≤ K ^ (2 : ℝ) := by exact Real.rpow_le_rpow hgx_nonneg hgx_le (by norm_num) have hg_sq_eq : g x ^ (2 : ℝ) = f x ^ p₀ := by calc g x ^ (2 : ℝ) = (f x ^ (p₀ / 2)) ^ (2 : ℝ) := by rfl _ = f x ^ ((p₀ / 2) * 2) := by rw [← Real.rpow_mul hfx_nonneg] _ = f x ^ p₀ := by congr 2 ring have hK_sq_eq : K ^ (2 : ℝ) = C_weakHarnack0 d * (A.1.Λ * p₀ ^ 2 + 1) ^ ((d : ℝ) / 2) * ∫ x in Metric.ball (0 : E) 1, |(u x)⁻¹| ^ p₀ ∂volume := by calc K ^ (2 : ℝ) = (C_weakHarnack0 d * (A.1.Λ * p₀ ^ 2 + 1) ^ ((d : ℝ) / 2) * ∫ x in Metric.ball (0 : E) 1, |(u x)⁻¹| ^ p₀ ∂volume) ^ ((1 / 2 : ℝ) * 2) := by dsimp [K] rw [← Real.rpow_mul (supersolutionInvBoundPow_nonneg (d := d) A)] _ = C_weakHarnack0 d * (A.1.Λ * p₀ ^ 2 + 1) ^ ((d : ℝ) / 2) * ∫ x in Metric.ball (0 : E) 1, |(u x)⁻¹| ^ p₀ ∂volume := by rw [show ((1 / 2 : ℝ) * 2) = (1 : ℝ) by ring, Real.rpow_one] calc |(u x)⁻¹| ^ p₀ = f x ^ p₀ := by rfl _ = g x ^ (2 : ℝ) := hg_sq_eq.symm _ ≤ K ^ (2 : ℝ) := hgpow _ = C_weakHarnack0 d * (A.1.Λ * p₀ ^ 2 + 1) ^ ((d : ℝ) / 2) * ∫ x in Metric.ball (0 : E) 1, |(u x)⁻¹| ^ p₀ ∂volume := hK_sq_eq- Project
- DeGiorgi
- License
- Apache-2.0
- Commit
- 4c1b3077d378
- Source
- DeGiorgi/Supersolutions/InverseIteration.lean:702-814
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Ae eq of tendsto e Lp Norm sub
BareFunction.ae_eq_of_tendsto_eLpNorm_sub
Plain-language statement
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Source project: DeGiorgi
Person-level attribution pending.
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Plain-language statement
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Source project: DeGiorgi
Person-level attribution pending.
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BareFunction.memLp_of_tendsto_eLpNorm
Plain-language statement
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Source project: DeGiorgi
Person-level attribution pending.