English
Related papers

Related papers: Words With Few Palindromes, Revisited

200 papers

We present a method which displays all palindromes of a given length from De Bruijn words of a certain order, and also a recursive one which constructs all palindromes of length $n+1$ from the set of palindromes of length $n$. We show that…

Discrete Mathematics · Computer Science 2010-02-16 M-C. Anisiu , V. Anisiu , Z. Kasa

We study the relation between the palindromic and factor complexity of infinite words. We show that for uniformly recurrent words one has P(n)+P(n+1) \leq \Delta C(n) + 2, for all n \in N. For a large class of words it is a better estimate…

Combinatorics · Mathematics 2007-05-23 Peter Baláži , Zuzana Masáková , Edita Pelantová

We show that a special case of the Feferman-Vaught composition theorem gives rise to a natural notion of automata for finite words over an infinite alphabet, with good closure and decidability properties, as well as several logical…

Logic in Computer Science · Computer Science 2015-07-01 Alexis Bès

We regard a finite word $u=u_1u_2\cdots u_n$ up to word isomorphism as an equivalence relation on $\{1,2,\ldots, n\}$ where $i$ is equivalent to $j$ if and only if $x_i=x_j.$ Some finite words (in particular all binary words) are generated…

Combinatorics · Mathematics 2014-04-04 Tero Harju , Mari Huova , L. Q. Zamboni

We introduce two classes of morphisms over the alphabet $A=\{0,1\}$ whose fixed points contain infinitely many antipalindromic factors. An antipalindrome is a finite word invariant under the action of the antimorphism…

Combinatorics · Mathematics 2019-06-17 Petr Ambrož , Zuzana Masáková , Edita Pelantová

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

A finite word $w$ is called \emph{rich} if it contains $\vert w\vert+1$ distinct palindromic factors including the empty word. For every finite rich word $w$ there are distinct nonempty palindromes $w_1, w_2,\dots,w_p$ such that…

Combinatorics · Mathematics 2022-04-26 Josef Rukavicka

We study the palindromic complexity of infinite words $u_\beta$, the fixed points of the substitution over a binary alphabet, $\phi(0)=0^a1$, $\phi(1)=0^b1$, with $a-1\geq b\geq 1$, which are canonically associated with quadratic non-simple…

Combinatorics · Mathematics 2016-08-16 L'ubomíra Balková , Zuzana Masáková

We show that the number of length-n words over a k-letter alphabet having no even palindromic prefix is the same as the number of length-n unbordered words, by constructing an explicit bijection between the two sets. A slightly different…

Discrete Mathematics · Computer Science 2020-06-05 Daniel Gabric , Jeffrey Shallit

A palindromic periodicity is a factor of an infinite word $(ps)^\omega$ where $p$ and $s$ are palindromes and the factor has length at least $|ps|$, for example, $accabaccab$. In this paper we describe several ways in which a palindromic…

Combinatorics · Mathematics 2024-05-02 Jamie Simpson

We prove a number of results on the structure and enumeration of palindromes and antipalindromes. In particular, we study conjugates of palindromes, palindromic pairs, rich words, and the counterparts of these notions for antipalindromes.

Formal Languages and Automata Theory · Computer Science 2016-09-13 Chuan Guo , Jeffrey Shallit , Arseny M. Shur

In this paper, we provide a new characterization of uniformly recurrent words with finite defect based on a relation between the palindromic and factor complexity. Furthermore, we introduce a class of morphisms P_ret closed under…

Combinatorics · Mathematics 2013-02-05 Lubomíra Balková , Edita Pelantová , Štěpán Starosta

Minimal forbidden factors are a useful tool for investigating properties of words and languages. Two factorial languages are distinct if and only if they have different (antifactorial) sets of minimal forbidden factors. There exist…

Formal Languages and Automata Theory · Computer Science 2018-05-28 Gabriele Fici , Antonio Restivo , Laura Rizzo

This paper studies the density of zero and one in subwords of the Fibonacci word with lengths less than thirty and compares them to the densities of their corresponding palindromes. We used computational methods to produce a sufficiently…

Combinatorics · Mathematics 2025-07-28 Duaa Abdullah , Jasem Hamoud

Prefix normal words are binary words in which each prefix has at least the same number of $\so$s as any factor of the same length. Firstly introduced by Fici and Lipt\'ak in 2011, the problem of determining the index of the prefix…

Formal Languages and Automata Theory · Computer Science 2020-05-20 Pamela Fleischmann , Mitja Kulczynski , Dirk Nowotka

The prefix palindromic length $p_{\mathbf{u}}(n)$ of an infinite word $\mathbf{u}$ is the minimal number of concatenated palindromes needed to express the prefix of length $n$ of $\mathbf{u}$. This function is surprisingly difficult to…

Combinatorics · Mathematics 2022-03-15 Dora V. Bulgakova , Anna E. Frid , Jérémy Scanvic

In this paper, we investigate the combinatorial and density properties of infinite words generated by Fibonacci-type morphisms, focusing on their subword structure, palindrome density, and extremal statistical behaviors. Using the morphism…

Combinatorics · Mathematics 2026-01-21 Duaa Abdullah , Jasem Hamoud

The paper explores combinatorial properties of Fibonacci words and their generalizations within the framework of combinatorics on words. These infinite sequences, measures the diversity of subwords in Fibonacci words, showing non-decreasing…

Combinatorics · Mathematics 2025-04-10 Jasem Hamoud , Duaa Abdullah

Fixed points ${\bf u}=\varphi({\bf u})$ of marked and primitive morphisms $\varphi$ over arbitrary alphabet are considered. We show that if ${\bf u}$ is palindromic, i.e., its language contains infinitely many palindromes, then some power…

Combinatorics · Mathematics 2015-09-14 Sébastien Labbé , Edita Pelantová

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