English

On the size of Nikodym sets in spaces over rings

Combinatorics 2021-01-01 v2 Classical Analysis and ODEs

Abstract

A Nikodym set N(Z/(NZ))n\mathcal{N}\subseteq(\mathbb{Z}/(N\mathbb{Z}))^n is a set containing L{x}L\setminus\{x\} for every x(Z/(NZ))nx\in(\mathbb{Z}/(N\mathbb{Z}))^n, where LL is a line passing through xx. We prove that if NN is square-free, then the size of every Nikodym set is at least cnNno(1)c_nN^{n-o(1)}, where cnc_n only depends on nn. This result is an extension of the result in the finite field case.

Keywords

Cite

@article{arxiv.2012.13554,
  title  = {On the size of Nikodym sets in spaces over rings},
  author = {Chengfei Xie and Gennian Ge},
  journal= {arXiv preprint arXiv:2012.13554},
  year   = {2021}
}

Comments

There is a much simpler proof