On finite $β$-expansions for the set of natural numbers

Fuente: arXiv
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Autori principali: Carvalho, Túlio O., Moreira, Catharina M.
Natura: Preprint
Pubblicazione: 2025
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author Carvalho, Túlio O.
Moreira, Catharina M.
author_facet Carvalho, Túlio O.
Moreira, Catharina M.
contents We present a study of the problem of finiteness of the $β$-expansions for the set of natural numbers, condition $F_1$ in brief, for three families of Pisot numbers for which the $β$-expansion of 1 is not a non-decreasing sequence. We show a class of simple $β$-numbers which display a puzzling behaviour, in the sense that an infinite subset of such $β$ satisfy $F_1$, whereas a complementary infinite subset does not. This puzzle is organized by the residue class modulo 3 of an integer coefficient of the main family of polynomials discussed. We prove that, when $F_1$ does not hold, the complement of ${{\rm Fin}(β)}$ is infinite. Finally, we give a concise sufficient condition for $F_1$, which is the finitude of the $β$-expansion of $(β-\lfloor β\rfloor)^2$.
format Preprint
id arxiv_https___arxiv_org_abs_2507_19604
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On finite $β$-expansions for the set of natural numbers
Carvalho, Túlio O.
Moreira, Catharina M.
Number Theory
Dynamical Systems
11K16, 37E15, 11A63
We present a study of the problem of finiteness of the $β$-expansions for the set of natural numbers, condition $F_1$ in brief, for three families of Pisot numbers for which the $β$-expansion of 1 is not a non-decreasing sequence. We show a class of simple $β$-numbers which display a puzzling behaviour, in the sense that an infinite subset of such $β$ satisfy $F_1$, whereas a complementary infinite subset does not. This puzzle is organized by the residue class modulo 3 of an integer coefficient of the main family of polynomials discussed. We prove that, when $F_1$ does not hold, the complement of ${{\rm Fin}(β)}$ is infinite. Finally, we give a concise sufficient condition for $F_1$, which is the finitude of the $β$-expansion of $(β-\lfloor β\rfloor)^2$.
title On finite $β$-expansions for the set of natural numbers
topic Number Theory
Dynamical Systems
11K16, 37E15, 11A63
url https://arxiv.org/abs/2507.19604