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arXiv · 2512.13180

Numeration systems without a dominant root and regularity

Émilie Charlier·Savinien Kreczman
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Abstract

Positional numeration systems are a large family of numeration systems used to represent natural numbers. Whether the set of all representations forms a regular language or not is one of the most important questions that can be asked of such a system. This question was investigated in a 1998 article by Hollander. Central to his analysis is a property linking positional numeration systems and R\'{e}nyi numeration systems, which use a real base to represent real numbers. However, this link only exists when the initial numeration system has a dominant root, which is not a necessary condition for regularity. In this article, we show a more general link between positional numeration systems and alternate base numeration systems, a family generalizing R\'{e}nyi systems. We then take advantage of this link to provide a full characterization of those numeration systems that generate a regular language. We also discuss the effectiveness of our method, and comment Hollander's results and conjecture in the light of ours.

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Émilie Charlier, Savinien Kreczman. 2025-12-15. Numeration systems without a dominant root and regularity. https://arxiv.org/abs/2512.13180

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