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arXiv · 1310.0309

An analogue of Cobham's theorem for graph directed iterated function systems

Emilie Charlier·Julien Leroy·Michel Rigo
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Abstract

Feng and Wang showed that two homogeneous iterated function systems in $\mathbb{R}$ with multiplicatively independent contraction ratios necessarily have different attractors. In this paper, we extend this result to graph directed iterated function systems in $\mathbb{R}^n$ with contraction ratios that are of the form $\frac{1}β$, for integers $β$. By using a result of Boigelot et al., this allows us to give a proof of a conjecture of Adamczewski and Bell. In doing so, we link the graph directed iterated function systems to Büchi automata. In particular, this link extends to real numbers $β$. We introduce a logical formalism that permits to characterize sets of $\mathbb{R}^n$ whose representations in base $β$ are recognized by some Büchi automata. This result depends on the algebraic properties of the base: $β$ being a Pisot or a Parry number. The main motivation of this work is to draw a general picture representing the different frameworks where an analogue of Cobham's theorem is known.

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Emilie Charlier, Julien Leroy, Michel Rigo. 2013-11-25. An analogue of Cobham's theorem for graph directed iterated function systems. https://arxiv.org/abs/1310.0309

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