BRIEF MESSAGES
On the intersection of two homogeneous Beatty sequences
A. V. Begunts,
D. V. Goryashin Lomonosov Moscow State University (Moscow)
Abstract:
Homogeneous Beatty sequences are sequences of the form
$a_n=[\alpha n]$, where
$\alpha$ is a positive irrational number. In 1957 T. Skolem showed that if the numbers
$1,\frac{1}{\alpha},\frac{1}{\beta}$ are linearly independent over the field of rational numbers, then the sequences
$[\alpha n]$ and
$[\beta n]$ have infinitely many elements in common. T. Bang strengthened this result: denote
$S_{\alpha,\beta}(N)$ the number of natural numbers
$k$,
$1\leqslant k\leqslant N$, that belong to both Beatty sequences
$[\alpha n]$,
$[\beta m]$, and the numbers
$1,\frac{1}{\alpha},\frac{1}{\beta}$ are linearly independent over the field of rational numbers, then
$S_{\alpha,\beta}(N)\sim \frac{N}{\alpha\beta}$ for
$N\to\infty.$
In this paper, we prove a refinement of this result for the case of algebraic numbers. Let
$\alpha,\beta>1$ be irrational algebraic numbers such that
$1,\frac{1}{\alpha},\frac{1}{\beta}$ are linearly independent over the field of rational numbers. Then for any
$\varepsilon>0$ the following asymptotic formula holds:
$$S_{\alpha,\beta}(N)=\frac{N}{\alpha\beta}+O\bigl(N^{\frac12+\varepsilon}\bigr), N\to\infty.$$
Keywords:
homogeneous Beatty sequence, exponential sums, asymptotic formula.
UDC:
511.35,
517.15 Received: 15.06.2022
Accepted: 22.12.2022
DOI:
10.22405/2226-8383-2022-23-5-145-151