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We prove a precise formula for the minimal number K(n) such that every binary word of length $n$ can be divided into K(n) palindromes. Also we estimate the average number $\ol K(n)$ of palindromes composing a random binary word of the…

Combinatorics · Mathematics 2011-05-20 Alex Ravsky

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

In 1999 Lyngs{\o} and Pedersen proposed a conjecture stating that every binary circular word of length $n$ with equal number of zeros and ones has an antipalindromic linear subsequence of length at least $\frac{2}{3}n$. No progress over a…

Formal Languages and Automata Theory · Computer Science 2019-01-23 Clemens Müllner , Andrew Ryzhikov

We focus on infinite words with languages closed under reversal. If frequencies of all factors are well defined, we show that the number of different frequencies of factors of length n+1 does not exceed 2C(n+1)-2C(n)+1.

Combinatorics · Mathematics 2013-02-12 L. Balkova , E. Pelantova

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

An infinite word has the property $R_m$ if every factor has exactly $m$ return words. Vuillon showed that $R_2$ characterizes Sturmian words. We prove that a word satisfies $R_m$ if its complexity function is $(m-1)n+1$ and if it contains…

Combinatorics · Mathematics 2007-09-27 Lubomira Balkova , Edita Pelantova , Wolfgang Steiner

Originally introduced and studied by the third and fourth authors together with J. Justin and S. Widmer in arXiv:0801.1656, rich words constitute a new class of finite and infinite words characterized by containing the maximal number of…

Combinatorics · Mathematics 2010-03-16 Michelangelo Bucci , Alessandro De Luca , Amy Glen , Luca Q. Zamboni

We introduce and study a complexity function on words $c_x(n),$ called \emph{cyclic complexity}, which counts the number of conjugacy classes of factors of length $n$ of an infinite word $x.$ We extend the well-known Morse-Hedlund theorem…

Formal Languages and Automata Theory · Computer Science 2016-06-29 Julien Cassaigne , Gabriele Fici , Marinella Sciortino , Luca Q. Zamboni

We study the $k$-Bonacci word over the infinite alphabet $\mathbb{N}$. Since the alphabet is infinite, the usual factor complexity is infinite and does not provide any information. We therefore investigate factor occurrence statistics in…

Combinatorics · Mathematics 2026-04-03 Narges Ghareghani , Mehdi Golafshan , Morteza Mohammad-Noori , Pouyeh Sharifani

We show that the 2-abelian complexity of the infinite Thue-Morse word is 2-regular, and other properties of the 2-abelian complexity, most notably that it is a concatenation of palindromes of increasing length. We also show sharp bounds for…

Combinatorics · Mathematics 2015-06-03 Florian Greinecker

We prove that every $n$-letter word over $k$-letter alphabet contains some word as a subsequence in at least $k^{n/4k(1+o(1))}$ many ways, and that this is sharp as $k\to\infty$. For fixed $k$, we show that the analogous number deviates…

Combinatorics · Mathematics 2025-09-29 Boris Bukh , Aleksandre Saatashvili

The Fibonacci word $W$ on an infinite alphabet was introduced in [Zhang et al., Electronic J. Combinatorics 2017 24(2), 2-52] as a fixed point of the morphism $2i\rightarrow (2i)(2i+1)$, $(2i+1) \rightarrow (2i+2)$, $i\geq 0$. Here, for any…

Combinatorics · Mathematics 2019-12-02 Narges Ghareghani , Pouyeh Sharifani , Morteza Mohammad-Noori

In this paper we introduce and study a new complexity measure for finite words. For positive integer $d$ special scattered subwords, called super-$d$-subwords, in which the gaps are of length at least $(d-1)$, are defined. We give methods…

Discrete Mathematics · Computer Science 2011-04-25 Zoltán Kása

A word is called closed if it has a prefix which is also its suffix and there is no internal occurrences of this prefix in the word. In this paper we study words that are rich in closed factors, i.e., which contain the maximal possible…

Combinatorics · Mathematics 2023-01-05 Olga Parshina , Svetlana Puzynina

This paper is concerned with palindromes occurring in characteristic Sturmian words $c_\alpha$ of slope $\alpha$, where $\alpha \in (0,1)$ is an irrational. As $c_\alpha$ is a uniformly recurrent infinite word, any (palindromic) factor of…

Combinatorics · Mathematics 2010-03-16 Amy Glen

Trapezoidal words are finite words having at most n+1 distinct factors of length n, for every n>=0. They encompass finite Sturmian words. We distinguish trapezoidal words into two disjoint subsets: open and closed trapezoidal words. A…

Formal Languages and Automata Theory · Computer Science 2011-08-19 Gabriele Fici

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

The palindromic length $\text{PL}(v)$ of a finite word $v$ is the minimal number of palindromes whose concatenation is equal to $v$. In 2013, Frid, Puzynina, and Zamboni conjectured that: If $w$ is an infinite word and $k$ is an integer…

Formal Languages and Automata Theory · Computer Science 2020-11-17 Josef Rukavicka

We consider the following problem. Let us fix a finite alphabet A; for any given d-uple of letter frequencies, how to construct an infinite word u over the alphabet A satisfying the following conditions: u has linear complexity function, u…

Formal Languages and Automata Theory · Computer Science 2011-08-19 Valérie Berthé , Sébastien Labbé

We prove that a random word of length $n$ over a $k$-ary fixed alphabet contains, on expectation, $\Theta(\sqrt{n})$ distinct palindromic factors. We study this number of factors, $E(n,k)$, in detail, showing that the limit…

Combinatorics · Mathematics 2016-09-13 Mikhail Rubinchik , Arseny M. Shur