Linfty almost periodicity boosted
AlmostPeriodicity.linfty_almost_periodicity_boosted
Plain-language statement
A boosted almost-periodicity estimate. Under , it finds a large set , with the stated lower bound , such that averaging the target convolution against the -fold convolution of changes it by at most in .
Exact Lean statement
public theorem linfty_almost_periodicity_boosted (ε : ℝ) (hε₀ : 0 < ε) (hε₁ : ε ≤ 1) (k : ℕ)
(hk : k ≠ 0) (hK₂ : 2 ≤ K) (hK : σ[A, S] ≤ K) (hS : S.Nonempty)
(B C : Finset G) (hB : B.Nonempty) (hC : C.Nonempty) :
∃ T : Finset G,
K ^ (-4096 * ⌈𝓛 (#C / #B)⌉ * k ^ 2/ ε ^ 2) * #S ≤ #T ∧
‖μ T ∗ᵈ^ k ∗ᵈ (μ_[ℂ] A ∗ᵈ 𝟭_[B] ∗ᵈ μ C) - μ A ∗ᵈ 𝟭_[B] ∗ᵈ μ C‖_[∞] ≤ εFormal artifact
Lean source
public theorem linfty_almost_periodicity_boosted (ε : ℝ) (hε₀ : 0 < ε) (hε₁ : ε ≤ 1) (k : ℕ) (hk : k ≠ 0) (hK₂ : 2 ≤ K) (hK : σ[A, S] ≤ K) (hS : S.Nonempty) (B C : Finset G) (hB : B.Nonempty) (hC : C.Nonempty) : ∃ T : Finset G, K ^ (-4096 * ⌈𝓛 (#C / #B)⌉ * k ^ 2/ ε ^ 2) * #S ≤ #T ∧ ‖μ T ∗ᵈ^ k ∗ᵈ (μ_[ℂ] A ∗ᵈ 𝟭_[B] ∗ᵈ μ C) - μ A ∗ᵈ 𝟭_[B] ∗ᵈ μ C‖_[∞] ≤ ε := by obtain ⟨T, hKT, hT⟩ := linfty_almost_periodicity (ε / k) (by positivity) (div_le_one_of_le₀ (hε₁.trans <| mod_cast Nat.one_le_iff_ne_zero.2 hk) <| by positivity) hK₂ hK _ _ hB hC refine ⟨T, by simpa only [div_pow, div_div_eq_mul_div] using hKT, ?_⟩ set F := μ_[ℂ] A ∗ᵈ 𝟭_[B] ∗ᵈ μ C have hT' : T.Nonempty := by have : (0 : ℝ) < #T := hKT.trans_lt' <| by positivity simpa [card_pos] using this calc (‖μ T ∗ᵈ^ k ∗ᵈ F - F‖_[∞] : ℝ) = ‖𝔼 a ∈ T ^^ k, (τ (∑ i, a i) F - F)‖_[∞] := by rw [mu_iterConv_ddconv, expect_sub_distrib, expect_const hT'.piFinset_const] _ ≤ 𝔼 a ∈ T ^^ k, ‖τ (∑ i, a i) F - F‖_[∞] := MeasureTheory.dLpNorm_expect_le le_top _ ≤ 𝔼 _a ∈ T ^^ k, ε := ?_ _ = ε := by rw [expect_const hT'.piFinset_const] refine expect_le_expect fun x hx ↦ calc (‖τ (∑ i, x i) F - F‖_[⊤] : ℝ) _ ≤ ∑ i, ‖τ (x i) F - F‖_[⊤] := MeasureTheory.dLpNorm_translate_sum_sub_le le_top _ _ _ _ ≤ ∑ _i, ε / k := by gcongr; exact hT _ <| Fintype.mem_piFinset.1 hx _ _ = ε := by simp only [sum_const, card_fin, nsmul_eq_mul]; rw [mul_div_cancel₀]; positivity- Project
- Arithmetic Progressions Almost Periodicity
- License
- Apache-2.0
- Commit
- afafc42a5326
- Source
- APAP/Physics/AlmostPeriodicity.lean:495-521
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Project documentation
If a finite set is additively dissociated, then its order- additive energy is at most , where is the project's Chang constant. This is the quantitative dissociated-set estimate used in the proof of Chang's lemma.
Source project: Arithmetic Progressions Almost Periodicity
Person-level attribution pending.
Linfty almost periodicity
AlmostPeriodicity.linfty_almost_periodicity
Project documentation
An almost-periodicity theorem. Under the small-growth hypothesis , and for nonempty finite sets , there is a set of translations with . Every changes the normalized convolution by at most in .
Source project: Arithmetic Progressions Almost Periodicity
Person-level attribution pending.
Ap in ff
ap_in_ff
Project documentation
A finite-field approximation lemma. If and each have density at least , then for any test set and there is a subspace of explicitly bounded codimension such that smoothing by the uniform measure on changes its total mass on by at most .
Source project: Arithmetic Progressions Almost Periodicity
Person-level attribution pending.