Bull. Korean Math. Soc. 2015; 52(4): 1047-1057
Printed July 31, 2015
https://doi.org/10.4134/BKMS.2015.52.4.1047
Copyright © The Korean Mathematical Society.
Ghorbel Rim and Zouari Sourour
Facult\'e des Sciences de Sfax, Facult\'e des Sciences de Sfax
In \cite{rhs1}, it is proved that the lengths of periods occurring in the $\beta$-expansion of a rational series $r$ noted by $Per_{\beta}(r)$ depend only on the denominator of the reduced form of $r$ for quadratic Pisot unit series. In this paper, we will show first that every rational $r$ in the unit disk has strictly periodic $\beta$-expansion for Pisot or Salem unit basis under some condition. Second, for this basis, if $r =\frac{P}{Q} $ is written in reduced form with $|P| < |Q|$, we will generalize the curious property ``$Per_{\beta}(\frac{P}{Q})=Per_{\beta}(\frac{1}{Q})$".
Keywords: formal power series, $\beta$-expansion, Pisot series, Salem series
MSC numbers: 11R06, 37B50
2012; 49(1): 127-133
2018; 55(6): 1811-1822
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