English

On Fourier coefficients of sets with small doubling

Combinatorics 2024-12-17 v1 Number Theory

Abstract

Let AA be a subset of a finite abelian group such that AA has a small difference set AAA-A and the density of AA is small. We prove that, counter--intuitively, the smallness (in terms of AA|A-A|) of the Fourier coefficients of AA guarantees that AA is correlated with a large Bohr set. Our bounds on the size and the dimension of the resulting Bohr set are close to exact.

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Cite

@article{arxiv.2412.11368,
  title  = {On Fourier coefficients of sets with small doubling},
  author = {Ilya D. Shkredov},
  journal= {arXiv preprint arXiv:2412.11368},
  year   = {2024}
}

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18 pages