fpvandoorn/carleson
Source indexedtheorem · leanprover/lean4:v4.32.0
MeasureTheory.BoundedCompactSupport.bddAbove_norm_carlesonOn
Carleson.Operators · Carleson/Operators.lean:93 to 142
Mathematical statement
Exact Lean statement
theorem BoundedCompactSupport.bddAbove_norm_carlesonOn
{f : X → ℂ} (hf : BoundedCompactSupport f) : BddAbove (range (‖carlesonOn p f ·‖))Complete declaration
Lean source
Full Lean sourceLean 4
theorem BoundedCompactSupport.bddAbove_norm_carlesonOn {f : X → ℂ} (hf : BoundedCompactSupport f) : BddAbove (range (‖carlesonOn p f ·‖)) := by let x₀ : X := Classical.choice inferInstance obtain ⟨r₀, hr₀, hfr₀⟩ := hf.hasCompactSupport.isBounded.subset_closedBall_lt 0 x₀ let r₁ := (↑D ^ 𝔰 p / 2) + r₀ have hcf : support (_root_.carlesonOn p f) ⊆ closedBall x₀ r₁ := by simp_rw [carlesonOn_def'] intro x hx simp only [mem_support] at hx apply indicator_apply_ne_zero.mp at hx replace hx := hx.2 simp only [mem_support] at hx have : ∃ y, Ks (𝔰 p) x y * f y * cexp (I * (Q x y - Q x x)) ≠ 0 := by by_contra! hc apply hx simp_rw [hc, integral_zero] obtain ⟨y, hy⟩ := this simp only [ne_eq, mul_eq_zero, exp_ne_zero, or_false, not_or] at hy apply le_trans <| dist_triangle _ y _ unfold r₁ gcongr exacts [(dist_mem_Icc_of_Ks_ne_zero hy.1).2, hfr₀ (subset_tsupport _ hy.2)] obtain ⟨CK, nnCK, hCK⟩ := Metric.isBounded_closedBall (x := x₀) (r := r₁) |>.exists_bound_of_norm_Ks (𝔰 p) let C := volume.real (closedBall x₀ r₀) * (CK * (eLpNorm f ⊤).toReal) rw [bddAbove_def] use C; simp_rw [mem_range, forall_exists_index, forall_apply_eq_imp_iff]; intro x by_cases hx : x ∈ support (_root_.carlesonOn p f); swap · simp only [mem_support, ne_eq, not_not] at hx rw [hx, norm_zero] positivity · simp_rw [carlesonOn_def'] apply le_trans <| norm_indicator_le_norm_self .. let g := (closedBall x₀ r₀).indicator (fun _ ↦ CK * (eLpNorm f ⊤).toReal) have hK : ∀ᵐ y, ‖Ks (𝔰 p) x y * f y * cexp (I * (Q x y - Q x x))‖ ≤ g y := by filter_upwards [hf.memLp_top.ae_norm_le] with y hy by_cases hy' : y ∈ support f · simp_rw [norm_mul, ← ofReal_sub, norm_exp_I_mul_ofReal, mul_one, g, indicator_of_mem (hfr₀ <|subset_tsupport _ hy' ) _] gcongr exact hCK x y (hcf hx) · simp_rw [notMem_support.mp hy', mul_zero, zero_mul, norm_zero, g] unfold indicator split_ifs <;> positivity calc _ ≤ ∫ y, g y := by refine norm_integral_le_of_norm_le ?_ hK exact Integrable.indicator_const measurableSet_closedBall measure_closedBall_lt_top _ = volume.real (closedBall x₀ r₀) * (CK * (eLpNorm f ⊤ volume).toReal) := integral_indicator_const _ measurableSet_closedBall