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We implement a decision procedure for answering questions about a class of infinite words that might be called (for lack of a better name) "Fibonacci-automatic". This class includes, for example, the famous Fibonacci word f = 01001010...,…

Formal Languages and Automata Theory · Computer Science 2014-07-29 Chen Fei Du , Hamoon Mousavi , Luke Schaeffer , Jeffrey Shallit

In 2005, Rampersad and the second author proved a number of theorems about infinite words x with the property that if w is any sufficiently long finite factor of x, then its reversal w^R is not a factor of x. In this note we revisit these…

Formal Languages and Automata Theory · Computer Science 2019-12-10 Lukas Fleischer , Jeffrey Shallit

This article studies the complexity of the word problem in groups of automorphisms of subshifts. We show in particular that for any Turing degree, there exists a subshift whose automorphism group contains a subgroup whose word problem has…

Computational Complexity · Computer Science 2018-09-05 Pierre Guillon , Emmanuel Jeandel , Jarkko Kari , Pascal Vanier

An infinite word is an infinite Lyndon word if it is smaller, with respect to the lexicographic order, than all its proper suffixes, or equivalently if it has infinitely many finite Lyndon words as prefixes. A characterization of binary…

Discrete Mathematics · Computer Science 2021-05-05 Gwenaël Richomme , Patrice Séébold

We study the cycle structure of words in several random permutations. We assume that the permutations are independent and that their distribution is conjugation invariant, with a good control on their short cycles. If, after successive…

Combinatorics · Mathematics 2023-10-24 Mohamed Slim Kammoun , Mylène Maïda

In [X. Droubay et al, Episturmian words and some constructions of de Luca and Rauzy, Theoret. Comput. Sci. 255 (2001)], it was proved that every word w has at most |w|+1 many distinct palindromic factors, including the empty word. The…

Combinatorics · Mathematics 2015-01-06 Jetro Vesti

We study decompositions of words into subwords that are in some sense similar, which means that one subword may be obtained from the other by a relatively simple transformation. Our main inspiration are shuffle squares, an intriguing class…

Combinatorics · Mathematics 2024-07-02 Jarosław Grytczuk , Bartłomiej Pawlik , Mariusz Pleszczyński

A finite word $w$ with $\vert w\vert=n$ contains at most $n+1$ distinct palindromic factors. If the bound $n+1$ is attained, the word $w$ is called \emph{rich}. Let $\Factor(w)$ be the set of factors of the word $w$. It is known that there…

Combinatorics · Mathematics 2019-09-06 Josef Rukavicka

An infinite word is S-automatic if, for all n>=0, its (n + 1)st letter is the output of a deterministic automaton fed with the representation of n in the considered numeration system S. In this extended abstract, we consider an analogous…

Formal Languages and Automata Theory · Computer Science 2009-07-06 Emilie Charlier , Tomi Karki , Michel Rigo

We analyze finite and infinite words coming from the symbolic version of Chacon's transformation, focusing on distances between such words. Our main result is that if W = 0010 0010 1 0010 ... is the infinite word usually associated with…

Dynamical Systems · Mathematics 2019-09-30 Patrick Bell , Hunter Brumley , Aaron Hill , Nathanael McGlothlin , Maireigh Nicholas , Tofunmi Ogunfunmi

We study infinite words coding an orbit under an exchange of three intervals which have full complexity $\C(n)=2n+1$ for all $n\in\N$ (non-degenerate 3iet words). In terms of parameters of the interval exchange and the starting point of the…

Combinatorics · Mathematics 2007-09-18 P. Baláži , Z. Masáková , E. Pelantová

The relationship between the length of a word and the maximum length of its unbordered factors is investigated in this paper. Consider a finite word w of length n. We call a word bordered, if it has a proper prefix which is also a suffix of…

Discrete Mathematics · Computer Science 2007-05-23 Tero Harju , Dirk Nowotka

An infinite word generated by a substitution is rigid if all the substitutions which fix this word are powers of a same substitution. Sturmian words as well as characteristic Arnoux-Rauzy words are known to be rigid. In the present paper,…

Discrete Mathematics · Computer Science 2025-06-30 Valérie Berthé , Svetlana Puzynina

For any integer $k>2$, the infinite $k$-bonacci word $W^{(k)}$, on the infinite alphabet is defined as the fixed point of the morphism $\varphi_k:\mathbb{N}\rightarrow \mathbb{N}^2 \cup \mathbb{N}$, where \begin{equation*} \varphi_k(ki+j) =…

Combinatorics · Mathematics 2019-12-12 Narges Ghareghani , Pouyeh Sharifani

In this paper we study the asymptotic behaviour of two relatively new complexity functions defined on infinite words and their relationship to periodicity. Given a factor $u$ of an infinite word $x$, we say $u$ is closed if it is a letter…

Combinatorics · Mathematics 2023-01-04 O. Parshina , M. Postic

Carpi (1993) and Lepisto (1994) proved independently that smooth words are cube-free for the alphabet {1, 2}, but nothing is known on whether for the other 2-letter alphabets, smooth words are k-power-free for some suitable positive integer…

Combinatorics · Mathematics 2011-08-10 Yunbao Huang

A group-word w is called concise if whenever the set of w-values in a group G is finite it always follows that the verbal subgroup w(G) is finite. More generally, a word w is said to be concise in a class of groups X if whenever the set of…

Group Theory · Mathematics 2014-06-30 Robert Guralnick , Pavel Shumyatsky

Weighted automata are nondeterministic automata with numerical weights on transitions. They can define quantitative languages~$L$ that assign to each word~$w$ a real number~$L(w)$. In the case of infinite words, the value of a run is…

Logic in Computer Science · Computer Science 2015-07-01 Krishnendu Chatterjee , Laurent Doyen , Thomas A Henzinger

We re-examine previous constructions of infinite binary words containing few distinct squares with the goal of finding the "simplest", in a certain sense. We exhibit several new constructions. Rather than using tedious case-based arguments…

Formal Languages and Automata Theory · Computer Science 2020-07-17 Daniel Gabric , Jeffrey Shallit

A double occurrence word $w$ over a finite alphabet $\Sigma$ is a word in which each alphabet letter appears exactly twice. Such words arise naturally in the study of topology, graph theory, and combinatorics. Recently, double occurrence…

Combinatorics · Mathematics 2012-05-01 Jonathan Burns , Tilahun Muche