Skip to Main Content


AMS eBook CollectionsOne of the world's most respected mathematical collections, available in digital format for your library or institution


Sums of Reciprocals of Fractional Parts and Multiplicative Diophantine Approximation

About this Title

Victor Beresnevich, Department of Mathematics, University of York, Heslington, York, YO10 5DD, United Kingdom, Alan Haynes, Department of Mathematics, University of Houston, Texas and Sanju Velani, Department of Mathematics, University of York, Heslington, York, YO10 5DD, United Kingdom

Publication: Memoirs of the American Mathematical Society
Publication Year: 2020; Volume 263, Number 1276
ISBNs: 978-1-4704-4095-4 (print); 978-1-4704-5660-3 (online)
DOI: https://doi.org/10.1090/memo/1276
Published electronically: February 24, 2020
Keywords: Multiplicative Diophantine approximation, Ostrowski expansion, uniform distribution
MSC: Primary 11K60, 11J71, 11A55, 11J83, 11J20, 11J70, 11K38, 11J54, 11K06, 11K50

View full volume PDF

View other years and numbers:

Table of Contents

1. Problems and main results

2. Developing techniques and establishing the main results

Abstract

There are two main interrelated goals of this paper. Firstly we investigate the sums \begin{equation*} S_N(\alpha ,\gamma ):=\sum _{n=1}^N\frac {1}{n\|n\alpha -\gamma \|} \end{equation*} and \begin{equation*} R_N(\alpha ,\gamma ):=\sum _{n=1}^N\frac {1}{\|n\alpha -\gamma \|}\,, \end{equation*} where $\alpha$ and $\gamma$ are real parameters and $\|\cdot \|$ is the distance to the nearest integer. Our theorems improve upon previous results of W. M. Schmidt and others, and are (up to constants) best possible. Related to the above sums, we also obtain upper and lower bounds for the cardinality of \begin{equation*} \{1\le n\le N:\|n\alpha -\gamma \|<\varepsilon \} \, , \end{equation*} valid for all sufficiently large $N$ and all sufficiently small $\varepsilon$. This first strand of the work is motivated by applications to multiplicative Diophantine approximation, which are also considered. In particular, we obtain complete Khintchine type results for multiplicative simultaneous Diophantine approximation on fibers in $\mathbb {R}^2$. The divergence result is the first of its kind and represents an attempt of developing the concept of ubiquity to the multiplicative setting.

References [Enhancements On Off] (What's this?)

References