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We characterize binary words that have exactly two unbordered conjugates and show that they can be expressed as a product of two palindromes.

Formal Languages and Automata Theory · Computer Science 2019-12-18 Štěpán Holub , Mike Müller

Two finite words $u$ and $v$ are called abelian equivalent if each letter occurs equally many times in both $u$ and $v$. The abelian closure $\mathcal{A}(\mathbf{x})$ of an infinite word $\mathbf{x}$ is the set of infinite words…

Combinatorics · Mathematics 2021-01-01 Juhani Karhumäki , Svetlana Puzynina , Markus A. Whiteland

In this paper we study the privileged complexity function of the Thue-Morse word. We prove a recursive formula describing this function, and using the formula we show that the function is unbounded and that the values of the function have…

Combinatorics · Mathematics 2015-07-23 Jarkko Peltomäki

We study infinite binary words that contain few distinct palindromes. In particular, we classify such words according to their critical exponents. This extends results by Fici and Zamboni [TCS 2013]. Interestingly, the words with 18 and 20…

Combinatorics · Mathematics 2024-03-27 L'ubomíra Dvořáková , Pascal Ochem , Daniela Opočenská

First introduced in the study of the Sturmian words, the iterated palindromic closure was recently generalized to pseudopalindromes. This operator allows one to construct words with an infinity of pseudopalindromic prefixes, called…

Combinatorics · Mathematics 2009-04-27 D. Jamet , G. Paquin , G. Richomme , L. Vuillon

Two finite words $u$ and $v$ are called Abelian equivalent if each letter occurs equally many times in both $u$ and $v$. The abelian closure $\mathcal{A}(\mathbf{x})$ of (the shift orbit closure of) an infinite word $\mathbf{x}$ is the set…

Combinatorics · Mathematics 2021-08-04 Svetlana Puzynina , Markus A. Whiteland

A word is closed if it contains a proper factor that occurs both as a prefix and as a suffix but does not have internal occurrences, otherwise it is open. We deal with the sequence of open and closed prefixes of Sturmian words and prove…

Combinatorics · Mathematics 2014-07-15 Alessandro De Luca , Gabriele Fici

We study cube-free words over arbitrary non-unary finite alphabets and prove the following structural property: for every pair $(u,v)$ of $d$-ary cube-free words, if $u$ can be infinitely extended to the right and $v$ can be infinitely…

Formal Languages and Automata Theory · Computer Science 2020-07-07 Elena A. Petrova , Arseny M. Shur

Any finite word $w$ of length $n$ contains at most $n+1$ distinct palindromic factors. If the bound $n+1$ is reached, the word $w$ is called rich. The number of rich words of length $n$ over an alphabet of cardinality $q$ is denoted…

Combinatorics · Mathematics 2019-03-26 Josef Rukavicka

We say that two finite words $u$ and $v$ are abelian equivalent if and only if they have the same number of occurrences of each letter, or equivalently if they define the same Parikh vector. In this paper we investigate various abelian…

Combinatorics · Mathematics 2009-04-21 Gwénaël Richomme , Kalle Saari , Luca Q. Zamboni

In this paper, we characterize by lexicographic order all finite Sturmian and episturmian words, i.e., all (finite) factors of such infinite words. Consequently, we obtain a characterization of infinite episturmian words in a "wide sense"…

Combinatorics · Mathematics 2010-03-16 Amy Glen , Jacques Justin , Giuseppe Pirillo

In this paper we study the class of so-called privileged words which have been previously considered only a little. We develop the basic properties of privileged words, which turn out to share similar properties with palindromes. Privileged…

Combinatorics · Mathematics 2013-08-20 Jarkko Peltomäki

A non-empty word $w$ is a border of the word $u$ if $\vert w\vert<\vert u\vert$ and $w$ is both a prefix and a suffix of $u$. A word $u$ with the border $w$ is closed if $u$ has exactly two occurrences of $w$. A word $u$ is privileged if…

Discrete Mathematics · Computer Science 2020-01-22 Josef Rukavicka

A word~$w$ has a border $u$ if $u$ is a non-empty proper prefix and suffix of $u$. A word~$w$ is said to be \emph{closed} if $w$ is of length at most $1$ or if $w$ has a border that occurs exactly twice in $w$. A word~$w$ is said to be…

Combinatorics · Mathematics 2024-05-24 Daniel Gabric

In this book chapter, written in French, we consider the classical family of Sturmian words, defined as the aperiodic infinite words containing only $n+1$ factors of a length $n$, which is the minimal possible value. We will discuss several…

Combinatorics · Mathematics 2019-05-14 Anna Frid

Two words are $k$-binomially equivalent if each subword of length at most $k$ occurs the same number of times in both words. The $k$-binomial complexity of an infinite word is a counting function that maps $n$ to the number of $k$-binomial…

Combinatorics · Mathematics 2022-12-07 Michel Rigo , Manon Stipulanti , Markus A. Whiteland

We consider questions related to the structure of infinite words (over an integer alphabet) with bounded additive complexity, i.e., words with the property that the number of distinct sums exhibited by factors of the same length is bounded…

Combinatorics · Mathematics 2012-09-24 Graham Banero

A palindrome is a word that reads the same left-to-right as right-to-left. We show that every simple group has a finite generating set $X$, such that every element of it can be written as a palindrome in the letters of $X$. Moreover, every…

Group Theory · Mathematics 2014-12-17 Elisabeth Fink , Andreas Thom

In [A. Frid, S. Puzynina, L.Q. Zamboni, \textit{On palindromic factorization of words}, Adv. in Appl. Math. 50 (2013), 737-748], it was conjectured that any infinite word whose palindromic lengths of factors are bounded is ultimately…

Formal Languages and Automata Theory · Computer Science 2016-06-21 Michelangelo Bucci , Gwenaël Richomme

We consider finite trees with edges labeled by letters on a finite alphabet $\varSigma$. Each pair of nodes defines a unique labeled path whose trace is a word of the free monoid $\varSigma^*$. The set of all such words defines the language…

Combinatorics · Mathematics 2015-05-12 Srečko Brlek , Nadia Lafrenière , Xavier Provençal