Transcendence for Pisot Morphic Words over an Algebraic Base

It is known that for a uniform morphic sequence$\boldsymbol u = \langle u_n\rangle_{n=0}^\infty$and an algebraic number$\beta$such that$|\beta|>1$ , the number$[\![\boldsymbol{u} ]\!]_\beta:=\sum_{n=0}^\infty \frac{u_n}{\beta^n}$either lies in$\mathbb Q(\beta)$or is transcendental. In this paper...

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Bibliographic Details
Main Authors Kebis, Pavol, Luca, Florian, Ouaknine, Joel, Scoones, Andrew, Worrell, James
Format Journal Article
LanguageEnglish
Published 06.05.2024
Subjects
Computer Science - Formal Languages and Automata Theory
Mathematics - Number Theory
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DOI10.48550/arxiv.2405.05279

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Summary:It is known that for a uniform morphic sequence$\boldsymbol u = \langle u_n\rangle_{n=0}^\infty$and an algebraic number$\beta$such that$|\beta|>1$ , the number$[\![\boldsymbol{u} ]\!]_\beta:=\sum_{n=0}^\infty \frac{u_n}{\beta^n}$either lies in$\mathbb Q(\beta)$or is transcendental. In this paper we show a similar rational-transcendental dichotomy for sequences defined by irreducible Pisot morphisms. Subject to the Pisot conjecture (an irreducible Pisot morphism has pure discrete spectrum), we generalise the latter result to arbitrary finite alphabets. In certain cases we are able to show transcendence of$[\![\boldsymbol{u}]\!]_{\beta}$outright. In particular, for$k\geq 2$ , if$\boldsymbol u$is the$k$ -bonacci word then$[\![\boldsymbol{u}]\!]_{\beta}$is transcendental.
DOI:10.48550/arxiv.2405.05279