Multiplicative combinatorial properties of return time sets in minimal dynamical systems
<p style='text-indent:20px;'>We investigate the relationship between the dynamical properties of minimal topological dynamical systems and the multiplicative combinatorial properties of return time sets arising from those systems. In particular, we prove that for a residual set of points in any minimal system, the set of return times to any non-empty, open set contains arbitrarily long geometric progressions. Under the separate assumptions of total minimality and distality, we prove that return time sets have positive multiplicative upper Banach density along <inline-formula><tex-math id="M1">\begin{document}$ \mathbb{N} $\end{document}</tex-math></inline-formula> and along cosets of multiplicative subsemigroups of <inline-formula><tex-math id="M2">\begin{document}$ \mathbb{N} $\end{document}</tex-math></inline-formula>, respectively. The primary motivation for this work is the long-standing open question of whether or not syndetic subsets of the positive integers contain arbitrarily long geometric progressions; our main result is some evidence for an affirmative answer to this question.</p>
1809.08702
2019
39
10
5891
REVIEWED
OTHER