English

An improvement on Furstenberg's intersection problem

Number Theory 2021-06-15 v3 Dynamical Systems Metric Geometry

Abstract

In this paper, we study a problem posed by Furstenberg on intersections between ×2,×3\times 2, \times 3 invariant sets. We present here a direct geometrical counting argument to revisit a theorem of Wu and Shmerkin. This argument can be used to obtain further improvements. For example, we show that if A2,A3[0,1]A_2,A_3\subset [0,1] are closed and ×2,×3\times 2, \times 3 invariant respectively, assuming that dimA2+dimA3<1\dim A_2+\dim A_3<1 then A2(uA3+v)A_2\cap (uA_3+v) is sparse (defined in this paper) and has box dimension zero uniformly with respect to the real parameters u,vu,v such that uu and u1u^{-1} are both bounded away from 00.

Keywords

Cite

@article{arxiv.1811.11073,
  title  = {An improvement on Furstenberg's intersection problem},
  author = {Han Yu},
  journal= {arXiv preprint arXiv:1811.11073},
  year   = {2021}
}

Comments

Accepted in Transactions of the american mathematical society

R2 v1 2026-06-23T06:22:15.908Z