English

Large sets avoiding infinite arithmetic / geometric progressions

Metric Geometry 2023-10-20 v1 Classical Analysis and ODEs

Abstract

We study some variants of the Erd\H{o}s similarity problem. We pose the question if every measurable subset of the real line with positive measure contains a similar copy of an infinite geometric progression. We construct a compact subset EE of the real line such that 00 is a Lebesgue density point of EE, but EE does not contain any (non-constant) infinite geometric progression. We give a sufficient density type condition that guarantees that a set contains an infinite geometric progression. By slightly improving a recent result of Bradford, Kohut and Mooroogen arXiv:2205.04786, we construct a closed set F[0,)F\subset[0,\infty) such that the measure of F[t,t+1]F\cap[t,t+1] tends to 11 at infinity but FF does not contain any infinite arithmetic progression. We also slightly improve a more general recent result by Kolountzakis and Papageorgiou arXiv:2208.02637 for more general sequences. We give a sufficient condition that guarantees that a given Cantor type set contains at least one infinite geometric progression with any quotient between 00 and 11. This can be applied to most symmetric Cantor sets of positive measure.

Keywords

Cite

@article{arxiv.2210.09284,
  title  = {Large sets avoiding infinite arithmetic / geometric progressions},
  author = {Alex Burgin and Samuel Goldberg and Tamás Keleti and Connor MacMahon and Xianzhi Wang},
  journal= {arXiv preprint arXiv:2210.09284},
  year   = {2023}
}
R2 v1 2026-06-28T03:50:40.950Z