Abstract
Let \(\beta >1\) be a non-integer. First we show that Lebesgue almost every number has a \(\beta \)-expansion of a given frequency if and only if Lebesgue almost every number has infinitely many \(\beta \)-expansions of the same given frequency. Then we deduce that Lebesgue almost every number has infinitely many balanced \(\beta \)-expansions, where an infinite sequence on the finite alphabet \(\{0,1 , \ldots ,m\}\) is called balanced if the frequency of the digit \(k\) is equal to the frequency of the digit \(m-k\) for all \(k\in \{0,1 , \ldots ,m\}\). Finally we consider variable frequency and prove that for every pseudo-golden ratio \(\beta \in (1,2)\), there exists a constant \(c=c(\beta )>0\) such that for any \(p\in [\frac{1}{2}-c,\frac{1}{2}+c]\), Lebesgue almost every \(x\) has infinitely many \(\beta \)-expansions with frequency of zeros equal to \(p\).
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Acknowledgement
The author is grateful to Professor Jean-Paul Allouche for his advices on a former version of this paper, and also grateful to the Oversea Study Program of Guangzhou Elite Project.
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Li, YQ. Digit frequencies of beta-expansions. Acta Math. Hungar. 162, 403–418 (2020). https://doi.org/10.1007/s10474-020-01032-7
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DOI: https://doi.org/10.1007/s10474-020-01032-7