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An intersection graph of curves in the plane is called a string graph. Matousek almost completely settled a conjecture of the authors by showing that every string graph of m edges admits a vertex separator of size O(\sqrt{m}\log m). In the…

Combinatorics · Mathematics 2013-03-01 Jacob Fox , Janos Pach

An outerstring graph is an intersection graph of curves that lie in a common half-plane and have one endpoint on the boundary of that half-plane. We prove that the class of outerstring graphs is $\chi$-bounded, which means that their…

Combinatorics · Mathematics 2018-12-04 Alexandre Rok , Bartosz Walczak

Where graphs are used for modelling and specifying systems, consistency is an important concern. To be a valid model of a system, the graph structure must satisfy a number of constraints. To date, consistency has primarily been viewed as a…

Logic in Computer Science · Computer Science 2021-11-02 Jens Kosiol , Daniel Strüber , Gabriele Taentzer , Steffen Zschaler

Graphs with bounded treewidth and bounded maximum degree are known to have tree-partitions of bounded width. What can be said if the bounded treewidth assumption is strengthened to bounded pathwidth? We prove that every graph with bounded…

Combinatorics · Mathematics 2026-05-28 David R. Wood

A graph $H$ is an induced subgraph of a graph $G$ if a graph isomorphic to $H$ can be obtained from $G$ by deleting vertices. Recently, there has been significant interest in understanding the unavoidable induced subgraphs for graphs of…

Combinatorics · Mathematics 2022-07-01 Robert Hickingbotham

String graphs, that is, intersection graphs of curves in the plane, have been studied since the 1960s. We provide an expository presentation of several results, including very recent ones: some string graphs require an exponential number of…

Combinatorics · Mathematics 2014-08-10 Jiří Matoušek

The treewidth of a graph is an important invariant in structural and algorithmic graph theory. This paper studies the treewidth of line graphs. We show that determining the treewidth of the line graph of a graph $G$ is equivalent to…

Combinatorics · Mathematics 2014-09-25 Daniel J. Harvey , David R. Wood

An axis-aligned string is a simple polygonal path, where each line segment is parallel to an axis in $\mathbb{R}^3$. Given a graph $G$, a string contact representation $\Psi$ of $G$ maps the vertices of $G$ to interior disjoint axis-aligned…

Computational Geometry · Computer Science 2017-07-11 Debajyoti Mondal

In this paper we investigate the connectedness and the isomorphism problems for zig-zag products of two graphs. A sufficient condition for the zig-zag product of two graphs to be connected is provided, reducing to the study of the…

Combinatorics · Mathematics 2017-03-10 Daniele D'Angeli , Alfredo Donno , Ecaterina Sava-Huss

We introduce H-clique-width, a new structural measure of graphs that aims to provide a hereditary analogue of the traditional graph product structure. The definition naturally generalises the ordinary clique-width concept. As a result, for…

Combinatorics · Mathematics 2026-05-08 Petr Hliněný , Jan Jedelský

A graph is said to be globally rigid if almost all embeddings of the graph's vertices in the Euclidean plane will define a system of edge-length equations with a unique (up to isometry) solution. In 2007, Jackson, Servatius and Servatius…

Combinatorics · Mathematics 2024-01-29 Sean Dewar

We show that planar graphs have bounded queue-number, thus proving a conjecture of Heath, Leighton and Rosenberg from 1992. The key to the proof is a new structural tool called layered partitions, and the result that every planar graph has…

Discrete Mathematics · Computer Science 2020-08-11 Vida Dujmović , Gwenaël Joret , Piotr Micek , Pat Morin , Torsten Ueckerdt , David R. Wood

A graph is an instrument which is extensively utilized to model various problems in different fields. Up to date, many graphs have been developed to represent algebraic structures, particularly rings in order to study their properties. In…

Combinatorics · Mathematics 2021-02-25 Mohammad Hassan Mudaber , Nor Haniza Sarmin , Ibrahim Gambo

Graph-level representations are crucial tools for characterising structural differences between graphs. However, comparing graphs with different cardinalities, even when sampled from the same underlying distribution, remains challenging.…

Machine Learning · Computer Science 2026-05-08 Katharina Limbeck , Nadja Häusermann , Martin Carrasco , Guy Wolf , Bastian Rieck

A vertex of degree one in a tree is called an end vertex and a vertex of degree at least three is called a branch vertex. For a graph $G$, let $\sigma_2$ be the minimum degree sum of two nonadjacent vertices in $G$. We consider tree…

Combinatorics · Mathematics 2015-05-19 Zhora Nikoghosyan

A \emph{queue layout} of a graph consists of a \emph{linear order} of its vertices and a partition of its edges into \emph{queues}, so that no two independent edges of the same queue are nested. The \emph{queue number} of a graph is the…

Data Structures and Algorithms · Computer Science 2019-08-12 Michael A. Bekos , Henry Förster , Martin Gronemann , Tamara Mchedlidze , Fabrizio Montecchiani , Chrysanthi Raftopoulou , Torsten Ueckerdt

Graphs provide a natural representation of relational structure that arises across diverse domains. Despite this ubiquity, graph structure is typically learned in a modality- and task-isolated manner, where graph representations are…

Machine Learning · Computer Science 2026-05-27 Ziming Li , Xiaoming Wu , Zehong Wang , Jiazheng Li , Yijun Tian , Jinhe Bi , Yunpu Ma , Yanfang Ye , Chuxu Zhang

In this paper, we study the graph isomorphism and graph automorphism problems. We propose a novel technique to analyze graph isomorphism and graph automorphism. Further we handled some strongly regular datasets for prove the efficiency of…

Combinatorics · Mathematics 2019-06-19 Sivakumar Karunakaran , Lavanya Selvaganesh

For a degree sequence, we define the set of edges that appear in every labeled realization of that sequence as forced, while the edges that appear in none as forbidden. We examine structure of graphs whose degree sequences contain either…

Combinatorics · Mathematics 2019-11-28 Brian Cloteaux

Classes of graphs with bounded expansion are a generalization of both proper minor closed classes and degree bounded classes. Such classes are based on a new invariant, the greatest reduced average density (grad) of G with rank r,…

Combinatorics · Mathematics 2007-05-23 Jaroslav Nesetril , Patrice Ossona De Mendez