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Project-declaredLean 4.32.0 · mathlib@81a5d257c8e4

Lintegral enorm carleson Sum le of is Antichain subset ℭ

lintegral_enorm_carlesonSum_le_of_isAntichain_subset_ℭ

Plain-language statement

Let A\mathfrak A be an antichain contained in the tile class C(k,n)\mathfrak C(k,n), and let ff be measurable with f(x)1F(x)\lVert f(x)\rVert\le\mathbf 1_F(x). On GGG\setminus G', the Carleson sum over the selected positive tiles in A\mathfrak A has an L1L^1 bound with exponential decay in the layer index nn:

GG+ ⁣CarlesonSumf(x)dxC(a,q)μ(G)11/qμ(F)1/q2((q1)/(8a4))n.\int_{G\setminus G'}^+\!\lVert\operatorname{CarlesonSum}f(x)\rVert\,dx\le C(a,q)\,\mu(G)^{1-1/q}\mu(F)^{1/q}\,2^{-((q-1)/(8a^4))n}.

Exact Lean statement

lemma lintegral_enorm_carlesonSum_le_of_isAntichain_subset_ℭ
    {f : X → ℂ} {𝔄 : Set (𝔓 X)} (hf : ∀ x, ‖f x‖ ≤ F.indicator 1 x) (h'f : Measurable f)
    (hA : IsAntichain (· ≤ ·) 𝔄) (h'A : 𝔄 ⊆ ℭ k n) :
    ∫⁻ x in G \ G', ‖carlesonSum (𝔓pos ∩ 𝔓₁ᶜ ∩ 𝔄) f x‖ₑ
    ≤ C2_0_3 a nnq * 2 ^ (a + 3) * volume G ^ (1 - q⁻¹) * volume F ^ (q⁻¹)
      * 2 ^ (- ((q - 1) / (8 * a ^ 4) * n))

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma lintegral_enorm_carlesonSum_le_of_isAntichain_subset_ℭ    {f : X  ℂ} {𝔄 : Set (𝔓 X)} (hf :  x, ‖f x‖  F.indicator 1 x) (h'f : Measurable f)    (hA : IsAntichain (·  ·) 𝔄) (h'A : 𝔄  ℭ k n) :    ∫⁻ x in G \ G', ‖carlesonSum (𝔓pos ∩ 𝔓₁ᶜ ∩ 𝔄) f x‖ₑ     C2_0_3 a nnq * 2 ^ (a + 3) * volume G ^ (1 - q⁻¹) * volume F ^ (q⁻¹)      * 2 ^ (- ((q - 1) / (8 * a ^ 4) * n)) := by  have I : 0  q - 1 := by linarith [one_lt_q X]  have J : 0  q⁻¹ - 2⁻¹ := inv_q_sub_half_nonneg X  apply (antichain_operator_le_volume (hA.subset inter_subset_right) h'f hf sdiff_subset).trans  simp only [mul_assoc]  apply mul_le_mul_right  have : dens₁ (𝔓pos (X := X) ∩ 𝔓₁ᶜ ∩ 𝔄)  2 ^ (4 * a - n + 1 : ) :=    dens1_le (inter_subset_right.trans h'A)  have : dens₂ (𝔓pos (X := X) ∩ 𝔓₁ᶜ ∩ 𝔄)  2 ^ (2 * a + 5) * volume F / volume G := by    rw [dens₂_eq_biSup_dens₂]    simp only [iSup_le_iff]    intro p hp    have : ¬ (𝓘 p : Set X)  G₁ := by      have W := hp.1.1      contrapose! W      have : ↑(𝓘 p) ∩ G ∩ G'ᶜ =:= by        simp only [G', compl_union]        apply eq_empty_of_subset_empty        intro x hx        exact (hx.2.1.1 (W hx.1.1)).elim      simp only [𝔓pos, mem_setOf_eq, this, measure_empty, lt_self_iff_false, not_false_eq_true]    contrapose! this    have : p  highDensityTiles := mem_preimage.mp this    apply subset_biUnion_of_mem this  calc  dens₁ (𝔓pos ∩ 𝔓₁ᶜ ∩ 𝔄) ^ ((q - 1) / (8 * ↑a ^ 4)) *    (dens₂ (𝔓pos ∩ 𝔓₁ᶜ ∩ 𝔄) ^ (q⁻¹ - 2⁻¹) * (volume F ^ (1 / 2 : ) * volume G ^ (1 / 2 : )))  _  (2 ^ (4 * a - n + 1 : )) ^ ((q - 1) / (8 * ↑a ^ 4)) *    ((2 ^ (2 * a + 5) * volume F / volume G) ^ (q⁻¹ - 2⁻¹)      * ((volume F ^ (1 / 2 : ) * volume G ^ (1 / 2 : )))) := by gcongr  _ = (2 ^ ((4 * a + 1) * (q - 1) / (8 * ↑a ^ 4)) * 2 ^ (- ((q - 1) / (8 * ↑a ^ 4) * n))) *    ((2 ^ ((2 * a + 5) * (q⁻¹ - 2⁻¹)) * volume F ^ (q⁻¹ - 2⁻¹) / volume G ^ (q⁻¹ - 2⁻¹))      * ((volume F ^ (1 / 2 : ) * volume G ^ (1 / 2 : )))) := by    rw [ENNReal.div_rpow_of_nonneg _ _ J, ENNReal.mul_rpow_of_nonneg _ _ J,       ENNReal.rpow_natCast,  ENNReal.rpow_mul,  ENNReal.rpow_mul,       ENNReal.rpow_add _ _ (NeZero.ne 2) ENNReal.ofNat_ne_top]    congr    · ring    · simp  _ = 2 ^ ((4 * a + 1) * (q - 1) / (8 * ↑a ^ 4)) * 2 ^ ((2 * a + 5) * (q⁻¹ - 2⁻¹)) *      (volume G ^ (1 - q⁻¹) * (volume F ^ q⁻¹ * 2 ^ (- ((q - 1) / (8 * ↑a ^ 4) * n)))) := by    rcases eq_or_ne (volume G) 0 with vG | vG    · have : 0 < 1 - q⁻¹ := by rw [sub_pos, inv_lt_one_iff₀]; exact .inr (one_lt_q X)      rw [vG, ENNReal.zero_rpow_of_pos (show 0 < (1 / 2 : ) by positivity),        ENNReal.zero_rpow_of_pos this]      simp only [zero_mul, mul_zero]    · have IF : (volume F) ^ (q⁻¹) = (volume F) ^ ((q ⁻¹ - 2⁻¹) + 2⁻¹) := by congr; abel      have IG : (volume G) ^ (1 - q⁻¹) = (volume G) ^ (2⁻¹ - (q⁻¹ - 2⁻¹)) := by        congr 1        simp only [sub_sub_eq_add_sub, sub_left_inj]        norm_num      rw [IF, IG, ENNReal.rpow_sub (2⁻¹) _ vG volume_G_ne_top,        ENNReal.rpow_add_of_nonneg (x := volume F) _ _ (inv_q_sub_half_nonneg X) (by norm_num),        ENNReal.div_eq_inv_mul, ENNReal.div_eq_inv_mul]      ring_nf  _  2 ^ ((2 : )⁻¹ + (a + 5/2)) *      (volume G ^ (1 - q⁻¹) * (volume F ^ q⁻¹ * 2 ^ (- ((q - 1) / (8 * ↑a ^ 4) * n)))) := by    rw [ ENNReal.rpow_add _ _ (NeZero.ne 2) ENNReal.ofNat_ne_top]    have : (4 : )  a := mod_cast (four_le_a X)    gcongr    · exact one_le_two    · calc      (4 * a + 1) * (q - 1) / (8 * a ^ 4 : )      _  (4 * a + a) * (2 - 1) / (8 * a ^ 4) := by         gcongr         · norm_cast           linarith [four_le_a X]         · exact q_le_two X      _ = 5 / (8 * a ^ 3) := by field_simp; norm_num      _  5 / (8 * (4 : ) ^ 3) := by gcongr      _  2⁻¹ := by norm_num    · calc      (2 * ↑a + 5) * (q⁻¹ - 2⁻¹)      _  (2 * ↑a + 5) * (1⁻¹ - 2⁻¹) := by gcongr; exact (one_lt_q X).le      _ = a + 5/2 := by ring  _ = 2 ^ (a + 3) *      (volume G ^ (1 - q⁻¹) * (volume F ^ q⁻¹ * 2 ^ (- ((q - 1) / (8 * ↑a ^ 4) * n)))) := by    congr 1    rw [ ENNReal.rpow_natCast]    congr    simp    ring
Project
Carleson formalization
License
Apache-2.0
Commit
74ef907d6bdb
Source
Carleson/Discrete/ForestComplement.lean:856-942

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Related declarations

Project-declaredLean 4.32.0

Ae tendsto zero of distribution le

ae_tendsto_zero_of_distribution_le

Plain-language statement

Suppose that, for every error threshold δ>0\delta>0 and every measure tolerance ε>0\varepsilon>0, one can choose N0N_0 so that the set where supN>N0f(x)FN(x)\sup_{N>N_0}\lVert f(x)-F_N(x)\rVert exceeds δ\delta has measure at most ε\varepsilon. Then FN(x)F_N(x) converges to f(x)f(x) for almost every xx.

harmonic analysisFourier analysismeasure theory

Source project: Carleson formalization

Person-level attribution pending.

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Project-declaredLean 4.32.0

Antichain operator

antichain_operator

Plain-language statement

For an antichain A\mathfrak{A} of pairwise incomparable tiles, and measurable functions ff and gg bounded by the indicators of FF and GG, the pairing of gg with the Carleson sum over A\mathfrak{A} is controlled by the L2L^2 norms of ff and gg and by positive powers of the two tile-density parameters. Concretely, the bound is

C(a,q)dens1(A)(q1)/(8a4)dens2(A)1/q1/2f2g2.C(a,q)\,\mathrm{dens}_1(\mathfrak{A})^{(q-1)/(8a^4)}\,\mathrm{dens}_2(\mathfrak{A})^{1/q-1/2}\,\lVert f\rVert_2\lVert g\rVert_2.

harmonic analysisFourier analysismeasure theory

Source project: Carleson formalization

Person-level attribution pending.

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