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Word-representable graphs, characterized by the existence of a semi-transitive orientation, form a well-studied class of graphs. Comparability graphs form another well-studied class and constitute a subclass of word-representable graphs.…

Discrete Mathematics · Computer Science 2026-05-15 Benny George Kenkireth , Gopalan Sajith , Sreyas Sasidharan

In this work, we investigate the relationship between $k$-repre\-sentable graphs and graphs representable by $k$-local words. In particular, we show that every graph representable by a $k$-local word is $(k+1)$-representable. A previous…

Combinatorics · Mathematics 2025-06-25 Philipp Böll , Pamela Fleischmann , Annika Huch , Jana Kreiß , Tim Löck , Kajus Park , Max Wiedenhöft

Given a connected graph $G$, the total mutual-visibility number of $G$, denoted $\mu_t(G)$, is the cardinality of a largest set $S\subseteq V(G)$ such that for every pair of vertices $x,y\in V(G)$ there is a shortest $x,y$-path whose…

Combinatorics · Mathematics 2023-06-29 Dorota Kuziak , Juan A. Rodríguez-Velázquez

The notion of a word-representable graph has been studied in a series of papers in the literature. A graph $G=(V,E)$ is word-representable if there exists a word $w$ over the alphabet $V$ such that letters $x$ and $y$ alternate in $w$ if…

Combinatorics · Mathematics 2014-12-17 Miles Jones , Sergey Kitaev , Artem Pyatkin , Jeffrey Remmel

The notion of word-representable graphs is a generalization of comparability graphs, in which graphs are represented by words. The complexity of word-representation of a word-representable graph is captured through the representation…

Combinatorics · Mathematics 2026-02-17 Khyodeno Mozhui , K. V. Krishna

In this work, we characterize the class of word-representable graphs with respect to the modular decomposition. Consequently, we determine the representation number of a word-representable graph in terms of the permutation-representation…

Combinatorics · Mathematics 2024-12-24 Tithi Dwary , K. V. Krishna

The $k$-independence number of a graph, $\alpha_k(G)$, is the maximum size of a set of vertices at pairwise distance greater than $k$, or alternatively, the independence number of the $k$-th power graph $G^k$. Although it is known that…

Combinatorics · Mathematics 2022-09-07 Aida Abiad , Hidde Koerts

A graph $G=(V,E)$ is word-representable if there exists a word $w$ over the alphabet $V$ such that letters $x$ and $y$ alternate in $w$ if and only if $xy$ is an edge in $E$. It is known that any word-representable graph $G$ is…

Combinatorics · Mathematics 2016-09-05 Marc Glen , Sergey Kitaev , Artem Pyatkin

Word-representable graphs are a class of graphs that can be represented by words, where edges and non-edges are determined by the alternation of letters in those words. Several papers in the literature have explored the…

Combinatorics · Mathematics 2025-08-22 Herman Z. Q. Chen , Humaira Hameed , Sergey Kitaev

In this work, we show that the class of word-representable graphs is closed under split recomposition and determine the representation number of the graph obtained by recomposing two word-representable graphs. Accordingly, we show that the…

Discrete Mathematics · Computer Science 2024-01-05 Tithi Dwary , K. V. Krishna

The literature on word-representable graphs is quite rich, and a number of variations of the original definition have been proposed over the years. We are initiating a systematic study of such variations based on formal languages. In our…

Discrete Mathematics · Computer Science 2024-11-06 Zhidan Feng , Henning Fernau , Pamela Fleischmann , Kevin Mann , Silas Cato Sacher

A graph is called $k$-representable if there exists a word $w$ over the nodes of the graph, each node occurring exactly $k$ times, such that there is an edge between two nodes $x,y$ if and only after removing all letters distinct from…

Combinatorics · Mathematics 2018-08-07 Bas Broere , Hans Zantema

A word-representable graph is a simple graph $G$ which can be represented by a word $w$ over the vertices of $G$ such that any two vertices are adjacent in $G$ if and only if they alternate in $w$. It is known that the class of…

Discrete Mathematics · Computer Science 2021-09-09 Khyodeno Mozhui , K. V. Krishna

A graph $G=(V,E)$ is a \emph{word-representable graph} if there exists a word $W$ over the alphabet $V$ such that letters $x$ and $y$ alternate in $W$ if and only if $(x,y)\in E$ for each $x\neq y$. In this paper we give an effective…

Combinatorics · Mathematics 2015-01-29 Magnús M. Halldórsson , Sergey Kitaev , Artem Pyatkin

A graph $G=(V,E)$ is word-representable if there exists a word $w$ over the alphabet $V$ such that letters $x$ and $y$ alternate in $w$ if and only if $(x,y)$ is an edge in $E$. A graph is word-representable if and only if it is…

Combinatorics · Mathematics 2014-03-10 Sergey Kitaev

This paper studies the choice number and paint number of the lexicographic product of graphs. We prove that if $G$ has maximum degree $\Delta$, then for any graph $H$ on $n$ vertices $ch(G[H]) \le (4\Delta+2)(ch(H) +\log_2 n)$ and…

Combinatorics · Mathematics 2015-12-08 Balázs Keszegh , Xuding Zhu

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$ labels that is preserved only by a trivial automorphism. The lexicographic product of…

Combinatorics · Mathematics 2016-06-28 Saeid Alikhani , Samaneh Soltani

A graph $G=(V,E)$ is word-representable if there exists a word $w$ over the alphabet $V$ such that letters $x$ and $y$ alternate in $w$ if and only if $(x,y)\in E$ for each $x\neq y$. The set of word-representable graphs generalizes several…

Combinatorics · Mathematics 2014-02-11 Andrew Collins , Sergey Kitaev , Vadim Lozin

Twin-width is a graph width parameter recently introduced by Bonnet, Kim, Thomass\'{e} & Watrigant. Given two graphs $G$ and $H$ and a graph product $\star$, we address the question: is the twin-width of $G\star H$ bounded by a function of…

Combinatorics · Mathematics 2024-02-14 William Pettersson , John Sylvester

For a graph $G$, $k(G)$ denotes its connectivity. A graph is super connected if every minimum vertex-cut isolates a vertex. Also $k_{1}$-connectivity of a connected graph is the minimum number of vertices whose deletion gives a disconnected…

Combinatorics · Mathematics 2020-09-11 Khalid Kamyab , Mohsen Ghasemi , Rezvan Varmazyar
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