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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

Canonical 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 : ) := by  have I (x : ) : 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  ) 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