fpvandoorn/carleson
Source indexedtheorem · leanprover/lean4:v4.32.0
antichain_operator'
Carleson.Antichain.AntichainOperator · Carleson/Antichain/AntichainOperator.lean:432 to 459
Source documentation
Version of the antichain operator theorem, but controlling the integral of the norm instead of the integral of the function multiplied by another function.
Exact Lean statement
theorem antichain_operator' {A : Set X} (h𝔄 : IsAntichain (· ≤ ·) 𝔄)
(hf : Measurable f) (hfF : ∀ x, ‖f x‖ ≤ F.indicator 1 x) (hA : A ⊆ G) :
∫⁻ x in A, ‖carlesonSum 𝔄 f x‖ₑ ≤
C2_0_3 a nnq * dens₁ 𝔄 ^ ((q - 1) / (8 * a ^ 4)) * dens₂ 𝔄 ^ (q⁻¹ - 2⁻¹) *
eLpNorm f 2 volume * volume G ^ (1/2 : ℝ)Complete declaration
Lean source
Full Lean sourceLean 4
theorem antichain_operator' {A : Set X} (h𝔄 : IsAntichain (· ≤ ·) 𝔄) (hf : Measurable f) (hfF : ∀ x, ‖f x‖ ≤ F.indicator 1 x) (hA : A ⊆ G) : ∫⁻ x in A, ‖carlesonSum 𝔄 f x‖ₑ ≤ C2_0_3 a nnq * dens₁ 𝔄 ^ ((q - 1) / (8 * a ^ 4)) * dens₂ 𝔄 ^ (q⁻¹ - 2⁻¹) * eLpNorm f 2 volume * volume G ^ (1/2 : ℝ) := by have I (x : ℝ) : x / x ≤ 1 := by rcases eq_or_ne x 0 with rfl | hx · simp · simp [hx] apply (lintegral_mono_set hA).trans /- This follows from the other version by taking for the test function `g` the argument of the sum to be controlled. -/ have bf := bcs_of_measurable_of_le_indicator_f hf hfF rw [← enorm_integral_starRingEnd_mul_eq_lintegral_enorm bf.carlesonSum.restrict.integrable] rw [← integral_indicator measurableSet_G] simp_rw [indicator_mul_left, ← Function.comp_def, Set.indicator_comp_of_zero (g := starRingEnd ℂ) (by simp)] apply (antichain_operator h𝔄 hf hfF (((measurable_carlesonSum hf).div (measurable_ofReal.comp (measurable_carlesonSum hf).norm) ).indicator measurableSet_G) (fun _ ↦ by simp [indicator]; split_ifs <;> simp [I])).trans gcongr calc _ ≤ eLpNorm (G.indicator (fun x ↦ 1) : X → ℝ) 2 volume := eLpNorm_mono (fun x ↦ by simp only [indicator]; split_ifs <;> simp [I]) _ ≤ _ := by rw [eLpNorm_indicator_const measurableSet_G (by norm_num) (by norm_num)] simp