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Sturmian words and Cantor sets arising from unique expansions over ternary alphabets

Published online by Cambridge University Press:  25 January 2018

DOYONG KWON
DOYONG KWON*
Affiliation:
Department of Mathematics, Chonnam National University, Gwangju 61186, Republic of Korea email [email protected]
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Abstract

Over a finite alphabet $A$ of real numbers, unique expansions in base $\unicode[STIX]{x1D6FD}$ are considered. A real number $G_{A}$ called the generalized golden ratio is a critical point of a situation of unique expansions. If $\unicode[STIX]{x1D6FD}<G_{A}$, then there are only trivial unique expansions in base $\unicode[STIX]{x1D6FD}$, while there are non-trivial unique expansions in base $\unicode[STIX]{x1D6FD}$ whenever $\unicode[STIX]{x1D6FD}>G_{A}$. Komornik, Lai and Pedicini [Generalized golden ratios of ternary alphabets. J. Eur. Math. Soc.13(4) (2011), 1113–1146] investigated the case where $A$ consists of three real numbers, and demonstrated that Sturmian words curiously emerge out of the generalized golden ratio. The present paper focuses on Sturmian words under this context. For a given alphabet $A=\{a_{1},a_{2},a_{3}\}$ with $a_{1}<a_{2}<a_{3}$, we give a complete characterization of the corresponding Sturmian words effectively and algorithmically, which reveals interesting structures behind the generalized golden ratios.

Type
Original Article
Information
Ergodic Theory and Dynamical Systems , Volume 39 , Issue 10 , October 2019 , pp. 2827 - 2854
Copyright
© Cambridge University Press, 2018 

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