Digit expansions in rational and algebraic basis

Fuente: arXiv
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Auteur principal: Rossi, Lucía
Format: Preprint
Publié: 2025
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author Rossi, Lucía
author_facet Rossi, Lucía
contents Consider $α\in \Q(i)$ satisfying $|α| >1$. Let $\D = \{0,1,\ldots,|a_0|-1\}$, where $a_0$ is the independent coefficient of the minimal primitive polynomial of $α$. We introduce a way of expanding complex numbers in base $α$ with digits in $\D$ that we call $α$-expansions, which generalize rational base number systems introduced by Akiyama, Frougny and Sakarovitch, and are related to rational self-affine tiles introduced by Steiner and Thuswaldner. We define an algorithm to obtain the expansions for certain Gaussian integers and show results on the language. We then extend the expansions to all $x \in \C$ (or $x \in \R$ when $α= \ab \in \Q$, the rational case will be our starting point) and show that they are unique almost everywhere. We relate them to tilings of the complex plane. We characterize $α$-expansions in terms of $p$-adic completions of $\Q(i)$ with respect to Gaussian primes.
format Preprint
id arxiv_https___arxiv_org_abs_2505_14150
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Digit expansions in rational and algebraic basis
Rossi, Lucía
Number Theory
11A63
Consider $α\in \Q(i)$ satisfying $|α| >1$. Let $\D = \{0,1,\ldots,|a_0|-1\}$, where $a_0$ is the independent coefficient of the minimal primitive polynomial of $α$. We introduce a way of expanding complex numbers in base $α$ with digits in $\D$ that we call $α$-expansions, which generalize rational base number systems introduced by Akiyama, Frougny and Sakarovitch, and are related to rational self-affine tiles introduced by Steiner and Thuswaldner. We define an algorithm to obtain the expansions for certain Gaussian integers and show results on the language. We then extend the expansions to all $x \in \C$ (or $x \in \R$ when $α= \ab \in \Q$, the rational case will be our starting point) and show that they are unique almost everywhere. We relate them to tilings of the complex plane. We characterize $α$-expansions in terms of $p$-adic completions of $\Q(i)$ with respect to Gaussian primes.
title Digit expansions in rational and algebraic basis
topic Number Theory
11A63
url https://arxiv.org/abs/2505.14150