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Project-declaredLean 4.32.0 · mathlib@81a5d257c8e4

Add Dissociated boring Energy le

AddDissociated.boringEnergy_le

Project documentation

If a finite set ss is additively dissociated, then its order-nn additive energy is at most CnnnsnC^n n^n |s|^n, where CC is the project's Chang constant. This is the quantitative dissociated-set estimate used in the proof of Chang's lemma.

Exact Lean statement

lemma AddDissociated.boringEnergy_le [MeasurableSpace G] [DiscreteMeasurableSpace G] [DecidableEq G]
    [Finite G] {s : Finset G} (hs : AddDissociated (s : Set G)) (n : ℕ) :
    boringEnergy n s ≤ changConst ^ n * n ^ n * #s ^ n

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma AddDissociated.boringEnergy_le [MeasurableSpace G] [DiscreteMeasurableSpace G] [DecidableEq G]    [Finite G] {s : Finset G} (hs : AddDissociated (s : Set G)) (n : ) :    boringEnergy n s  changConst ^ n * n ^ n * #s ^ n := by  cases nonempty_fintype G  obtain rfl | hn := eq_or_ne n 0  · simp  calc    _ = (‖dft 𝟭_[(s : Set G)]‖ₙ_[↑(2 * n)] ^ (2 * n) : ) := by rw [cLpNorm_dft_indicator_one_pow]    _  (4 * rexp 2⁻¹ * sqrt ↑(2 * n) * ‖dft 𝟭_[(s : Set G)]‖ₙ_[2]) ^ (2 * n) := by        gcongr        refine rudin_ineq (le_mul_of_one_le_right zero_le_two <| Nat.one_le_iff_ne_zero.2 hn)          (dft 𝟭_[(s : Set G), ℂ]) ?_        rwa [cft_dft, support_comp_eq_preimage, Set.support_indicator_one, Set.preimage_comp,          Set.neg_preimage, addDissociated_neg, AddEquiv.addDissociated_preimage]    _ = _ := by        simp_rw [mul_pow, pow_mul, cL2Norm_dft_indicator_one]        rw [ exp_nsmul, sq_sqrt (by positivity), sq_sqrt (by positivity)]        simp_rw [ mul_pow]        simp [changConst]        ring_nf
Project
Arithmetic Progressions Almost Periodicity
License
Apache-2.0
Commit
afafc42a5326
Source
APAP/Prereqs/Chang.lean:67-86

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Project-declaredLean 4.32.0

Linfty almost periodicity

AlmostPeriodicity.linfty_almost_periodicity

Project documentation

An LL^\infty almost-periodicity theorem. Under the small-growth hypothesis σ[A,S]K\sigma[A,S]\le K, and for nonempty finite sets B,CB,C, there is a set of translations TT with TK4096L(C/B)/ε2S|T|\ge K^{-4096\lceil\mathcal L(|C|/|B|)\rceil/\varepsilon^2}|S|. Every tTt\in T changes the normalized convolution μA1BμC\mu_A*1_B*\mu_C by at most ε\varepsilon in LL^\infty.

additive combinatoricsarithmetic progressionsFourier analysis

Source project: Arithmetic Progressions Almost Periodicity

Person-level attribution pending.

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Project-declaredLean 4.32.0

Linfty almost periodicity boosted

AlmostPeriodicity.linfty_almost_periodicity_boosted

Plain-language statement

A boosted LL^\infty almost-periodicity estimate. Under σ[A,S]K\sigma[A,S]\le K, it finds a large set TT, with the stated lower bound TK4096L(C/B)k2/ε2S|T|\ge K^{-4096\lceil\mathcal L(|C|/|B|)\rceil k^2/\varepsilon^2}|S|, such that averaging the target convolution against the kk-fold convolution of μT\mu_T changes it by at most ε\varepsilon in LL^\infty.

additive combinatoricsarithmetic progressionsFourier analysis

Source project: Arithmetic Progressions Almost Periodicity

Person-level attribution pending.

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Project-declaredLean 4.32.0

Ap in ff

ap_in_ff

Project documentation

A finite-field approximation lemma. If A1A_1 and A2A_2 each have density at least α\alpha, then for any test set SS and 0<ε10<\varepsilon\le1 there is a subspace VV of explicitly bounded codimension such that smoothing μA1μA2\mu_{A_1}*\mu_{A_2} by the uniform measure on VV changes its total mass on SS by at most ε\varepsilon.

additive combinatoricsarithmetic progressionsFourier analysis

Source project: Arithmetic Progressions Almost Periodicity

Person-level attribution pending.

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