English

Incidence bounds with M\"obius hyperbolae in positive characteristic

Combinatorics 2021-04-22 v1

Abstract

We prove new incidence bounds between a plane point set, which is a Cartesian product, and a set of translates HH of the hyperbola xy=λ0xy=\lambda\neq 0, over a field of asymptotically large positive characteristic pp. They improve recent bounds by Shkredov, which are based on using explicit incidence estimates in the early terminated procedure of repeated applications of the Cauchy-Schwarz inequality, underlying many qualitative results related to growth and expansion in groups. The improvement -- both quantitative, plus we are able to deal with a general HH, rather than a Cartesian product -- is mostly due to a non-trivial "intermediate" bound on the number of kk-rich M\"obius hyperbolae in positive characteristic. In addition, we make an observation that a certain energy-type quantity in the context of HH can be bounded via the L2L^2-moment of the Minkowski distance in HH and can therefore fetch the corresponding estimates apropos of the Erd\H{o}s distinct distance problem.

Keywords

Cite

@article{arxiv.2104.10534,
  title  = {Incidence bounds with M\"obius hyperbolae in positive characteristic},
  author = {Misha Rudnev and James Wheeler},
  journal= {arXiv preprint arXiv:2104.10534},
  year   = {2021}
}

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17 pages