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Letters $x$ and $y$ alternate in a word $w$ if after deleting in $w$ all letters but the copies of $x$ and $y$ we either obtain a word $xyxy\cdots$ (of even or odd length) or a word $yxyx\cdots$ (of even or odd length). A graph $G=(V,E)$ is…

Combinatorics · Mathematics 2017-05-18 Sergey Kitaev

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

A graph $G = (V, E)$ is word-representable, if there exists a word w over the alphabet V such that for letters ${x, y} \in V$ , $x$ and $y$ alternate in $w$ if and only if $xy \in E$. In this paper, we prove that any non-empty…

Combinatorics · Mathematics 2026-01-29 Biswajit Das , Ramesh Hariharasubramanian

A graph $G=(V,E)$ is word-representable if and only if there exists a word $w$ over the alphabet $V$ such that letters $x$ and $y$, $x\neq y$, alternate in $w$ if and only if $xy\in E$. A split graph is a graph in which the vertices can be…

Combinatorics · Mathematics 2021-05-03 Kittitat Iamthong

Recently researchers working in the LFG framework have proposed algorithms for taking advantage of the implicit context-free components of a unification grammar [Maxwell 96]. This paper clarifies the mathematical foundations of these…

cmp-lg · Computer Science 2008-02-03 Marc Dymetman

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 $(x,y)\in E$ for each $x\neq y$. The set of word-representable graphs generalizes several…

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

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

In this article we give two different ways of representations of circular words. Representations with tuples are intended as a compact notation, while representations with trees give a way to easily process all conjugates of a word. The…

Formal Languages and Automata Theory · Computer Science 2014-05-23 László Hegedüs , Benedek Nagy

Given a set $F$ of words, one associates to each word $w$ in $F$ an undirected graph, called its extension graph, and which describes the possible extensions of $w$ on the left and on the right. We investigate the family of sets of words…

Word-representable graphs are a subset of graphs that may be represented by a word $w$ over an alphabet composed of the vertices in the graph. In such graphs, an edge exists if and only if the occurrences of the corresponding vertices…

Data Structures and Algorithms · Computer Science 2025-02-12 Duncan Adamson

Given a string $T$, it is known that its suffix tree can be represented using the compact directed acyclic word graph (CDAWG) with $e_T$ arcs, taking overall $O(e_T+e_{{\overline{T}}})$ words of space, where ${\overline{T}}$ is the reverse…

Data Structures and Algorithms · Computer Science 2017-05-25 Djamal Belazzougui , Fabio Cunial

A graph is word-representable if it can be represented in a certain way using alternation of letters in words. Word-representable graphs generalise several important and well-studied classes of graphs, and they can be characterised by…

Combinatorics · Mathematics 2023-06-19 Sergey Kitaev , Haoran Sun

Word-representable graphs, which are the same as semi-transitively orientable graphs, generalize several fundamental classes of graphs. In this paper we propose a novel approach to study word-representability of graphs using a technique of…

Combinatorics · Mathematics 2023-12-19 Sumin Huang , Sergey Kitaev , Artem Pyatkin

For any context-free grammar, we build a transition diagram, that is, a finite directed graph with labeled arcs, which describes the work of the grammar. This approach is new, and it is different from previously known graph models. We…

Formal Languages and Automata Theory · Computer Science 2013-05-30 Krasimir Yordzhev

A graph $G$ with vertex set $V(G)$ and edge set $E(G)$ is said to be word-representable if there exists a word $w$ over the alphabet $V(G)$ such that, for any two distinct letters $x,y \in V(G)$, the letters $x$ and $y$ alternate in $w$ if…

Combinatorics · Mathematics 2026-04-14 Eshwar Srinivasan , Ramesh Hariharasubramanian

A simple 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 $w$ iff $xy\in E$. Word-representable graphs generalize several important classes of graphs. A graph…

Combinatorics · Mathematics 2019-10-03 Özgür Akgün , Ian P. Gent , Sergey Kitaev , Hans Zantema

In this thesis we present a semantic representation formalism based on directed graphs and explore its linguistic adequacy and explanatory benefits in the semantics of plurality and quantification. Our graph language covers the essentials…

Computation and Language · Computer Science 2021-12-14 Yu Cao

Distinct letters $x$ and $y$ alternate in a word $w$ if after deleting in $w$ all letters but the copies of $x$ and $y$ we either obtain a word of the form $xyxy\cdots$ (of even or odd length) or a word of the form $yxyx\cdots$ (of even or…

Combinatorics · Mathematics 2019-07-23 Gi-Sang Cheon , Jinha Kim , Minki Kim , Sergey Kitaev

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
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