State Complexity of Shifts of the Fibonacci Word

Fuente: arXiv
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Main Authors: Moradi, Delaram, Popoli, Pierre, Shallit, Jeffrey, Vukusic, Ingrid
Format: Preprint
Published: 2026
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author Moradi, Delaram
Popoli, Pierre
Shallit, Jeffrey
Vukusic, Ingrid
author_facet Moradi, Delaram
Popoli, Pierre
Shallit, Jeffrey
Vukusic, Ingrid
contents The Fibonacci infinite word ${\bf f} = (f_i)_{i \geq 0} = 01001010\cdots$ is one of the most celebrated objects in combinatorics on words. There is a simple $5$-state automaton that, given $i$ in lsd-first Zeckendorf representation, computes its $i$'th term $f_i$, and a $2$-state automaton for msd-first. In this paper we consider the state complexity of the automaton generating the shifted sequence $(f_{i+c})_{i \geq 0}$, and show that it is $O(\log c)$ for both msd-first and lsd-first input. This is close to the information-theoretic minimum for an aperiodic sequence. The techniques involve a mixture of state complexity techniques and Diophantine approximation.
format Preprint
id arxiv_https___arxiv_org_abs_2603_18858
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle State Complexity of Shifts of the Fibonacci Word
Moradi, Delaram
Popoli, Pierre
Shallit, Jeffrey
Vukusic, Ingrid
Formal Languages and Automata Theory
Discrete Mathematics
Number Theory
The Fibonacci infinite word ${\bf f} = (f_i)_{i \geq 0} = 01001010\cdots$ is one of the most celebrated objects in combinatorics on words. There is a simple $5$-state automaton that, given $i$ in lsd-first Zeckendorf representation, computes its $i$'th term $f_i$, and a $2$-state automaton for msd-first. In this paper we consider the state complexity of the automaton generating the shifted sequence $(f_{i+c})_{i \geq 0}$, and show that it is $O(\log c)$ for both msd-first and lsd-first input. This is close to the information-theoretic minimum for an aperiodic sequence. The techniques involve a mixture of state complexity techniques and Diophantine approximation.
title State Complexity of Shifts of the Fibonacci Word
topic Formal Languages and Automata Theory
Discrete Mathematics
Number Theory
url https://arxiv.org/abs/2603.18858