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Main Authors: Krishnamoorthy, Abhishek, Thamburaj, Robinson, Thomas, Durairaj Gnanaraj
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2507.15313
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author Krishnamoorthy, Abhishek
Thamburaj, Robinson
Thomas, Durairaj Gnanaraj
author_facet Krishnamoorthy, Abhishek
Thamburaj, Robinson
Thomas, Durairaj Gnanaraj
contents Sturmian words form a family of one-sided infinite words over a binary alphabet that are obtained as a discretization of a line with an irrational slope starting from the origin. A finite version of this class of words called Christoffel words has been extensively studied for their interesting properties. It is a class of words that has a geometric and an algebraic definition, making it an intriguing topic of study for many mathematicians. Recently, a generalization of Christoffel words for an alphabet with 3 letters or more, called epichristoffel words, using episturmian morphisms has been studied, and many of the properties of Christoffel words have been shown to carry over to epichristoffel words; however, many properties are not shared by them as well. In this paper, we introduce the notion of an epichristoffel tree, which proves to be a useful tool in determining a subclass of epichristoffel words that share an important property of Christoffel words, which is the ability to factorize an epichristoffel word as a product of smaller epichristoffel words. We also use the epichristoffel tree to present some interesting results that help to better understand epichristoffel words.
format Preprint
id arxiv_https___arxiv_org_abs_2507_15313
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On a Generalization of the Christoffel Tree: Epichristoffel Trees
Krishnamoorthy, Abhishek
Thamburaj, Robinson
Thomas, Durairaj Gnanaraj
Formal Languages and Automata Theory
G.2.1:F.2.2
Sturmian words form a family of one-sided infinite words over a binary alphabet that are obtained as a discretization of a line with an irrational slope starting from the origin. A finite version of this class of words called Christoffel words has been extensively studied for their interesting properties. It is a class of words that has a geometric and an algebraic definition, making it an intriguing topic of study for many mathematicians. Recently, a generalization of Christoffel words for an alphabet with 3 letters or more, called epichristoffel words, using episturmian morphisms has been studied, and many of the properties of Christoffel words have been shown to carry over to epichristoffel words; however, many properties are not shared by them as well. In this paper, we introduce the notion of an epichristoffel tree, which proves to be a useful tool in determining a subclass of epichristoffel words that share an important property of Christoffel words, which is the ability to factorize an epichristoffel word as a product of smaller epichristoffel words. We also use the epichristoffel tree to present some interesting results that help to better understand epichristoffel words.
title On a Generalization of the Christoffel Tree: Epichristoffel Trees
topic Formal Languages and Automata Theory
G.2.1:F.2.2
url https://arxiv.org/abs/2507.15313