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We generalize recent work of Andrews, Just, and Simay on modular palindromic compositions and anti-palindromic compositions by viewing all compositions partially (modular) palindromic or anti-palindromic. More precisely, we enumerate…

Combinatorics · Mathematics 2023-03-20 Jia Huang

We prove that the Fibonacci word $f$ satisfies among all characteristic Sturmian words, three interesting extremal properties. The first concerns the length and the second the minimal period of its palindromic prefixes. Each of these two…

Discrete Mathematics · Computer Science 2012-09-19 Aldo de Luca

We exhibit the construction of a deterministic automaton that, given k > 0, recognizes the (regular) language of k-differentiable words. Our approach follows a scheme of Crochemore et al. based on minimal forbidden words. We extend this…

Discrete Mathematics · Computer Science 2015-03-18 Jean-Marc Fédou , Gabriele Fici

Following a recent paper of Anselmo et al., we consider $m \times n$ rectangular matrices formed from the Fibonacci word, and we show that their balance properties can be solved with a finite automaton. We also generalize the result to…

Number Theory · Mathematics 2026-04-22 Jeffrey Shallit , Ingrid Vukusic

We introduce a new geometric approach to Sturmian words by means of a mapping that associates certain lines in the n x n -grid and sets of finite Sturmian words of length n. Using this mapping, we give new proofs of the formulas enumerating…

Discrete Mathematics · Computer Science 2012-01-24 Kaisa Matomäki , Kalle Saari

In this paper, we extend the notion of Lyndon word to transfinite words. We prove two main results. We first show that, given a transfinite word, there exists a unique factorization in Lyndon words that are densely non-increasing, a…

Formal Languages and Automata Theory · Computer Science 2023-06-22 Olivier Carton , Luc Boasson

We explore a natural class of semigroups that have word problem decidable by finite state automata. Among the main results are invariance of this property under change of generators, invariance under basic algebraic constructions and…

Formal Languages and Automata Theory · Computer Science 2019-10-17 Max Neunhöffer , Markus Pfeiffer , Nik Ruskuc

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

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

We study the palindromic length of factors of infinite words fixed by morphisms of the so-called class $\mathcal{P}$ introduced by Hof, Knill and Simon. We show that it grows at most logarithmically with the length of the factor. For the…

Combinatorics · Mathematics 2018-12-05 Petr Ambrož , Ondřej Kadlec , Zuzana Masáková , Edita Pelantová

The notion of palindromic length of a finite word, as well as an infinite word, was first introduced by Frid, Puzynina and Zamboni\cite{FRID2013737}. They conjectured that if the palindromic length of an infinite word is bounded, then this…

Combinatorics · Mathematics 2019-07-30 Shuo Li

The Fibonacci sequence $\mathbb{F}$ is the fixed point beginning with $a$ of morphism $\sigma(a,b)=(ab,a)$. Since $\mathbb{F}$ is uniformly recurrent, each factor $\omega$ appears infinite many times in the sequence which is arranged as…

Dynamical Systems · Mathematics 2016-04-19 Huang Yuke , Wen Zhiying

The present paper records more details of the relationship between primitive elements and palindromes in F_2, the free group of rank two. We characterise the conjugacy classes of primitive elements which contain palindromes as those which…

Group Theory · Mathematics 2019-02-07 Adam Piggott

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

We prove that if a uniformly recurrent infinite word contains as a factor any finite permutation of words from an infinite family, then either this word is periodic, or its complexity (that is, the number of factors) grows faster than…

Combinatorics · Mathematics 2015-10-29 Anna E. Frid

In the study of infinite words, various notions of balancedness provide quantitative measures for how regularly letters or factors occur, and they find applications in several areas of mathematics and theoretical computer science. In this…

Combinatorics · Mathematics 2026-02-04 Bastiàn Espinoza , Pierre Popoli , Manon Stipulanti

We study infinite words u over an alphabet A satisfying the property P : P(n)+ P(n+1) = 1+ #A for any n in N, where P(n) denotes the number of palindromic factors of length n occurring in the language of u. We study also infinite words…

Combinatorics · Mathematics 2013-02-12 Lubomira Balkova , Edita Pelantova , Stepan Starosta

In this paper, we consider infinite words that arise as fixed points of primitive substitutions on a finite alphabet and finite colorings of their factors. Any such infinite word exhibits a "hierarchal structure" that will allow us to…

Combinatorics · Mathematics 2016-05-31 A. Bernardino , M. Silva , R. Pacheco

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

Prefix normal words are binary words that have no factor with more $1$s than the prefix of the same length. Finite prefix normal words were introduced in [Fici and Lipt\'ak, DLT 2011]. In this paper, we study infinite prefix normal words…

Combinatorics · Mathematics 2021-05-31 Ferdinando Cicalese , Zsuzsanna Lipták , Massimiliano Rossi