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Given two $n$-vertex graphs $G_1$ and $G_2$ of bounded treewidth, is there an $n$-vertex graph $G$ of bounded treewidth having subgraphs isomorphic to $G_1$ and $G_2$? Our main result is a negative answer to this question, in a strong…

Combinatorics · Mathematics 2024-02-13 Bogdan Alecu , Vadim Lozin , Daniel A. Quiroz , Roman Rabinovich , Igor Razgon , Viktor Zamaraev

The bandwidth of a $n$-vertex graph $G$ is the smallest integer $b$ such that there exists a bijective function $f : V(G) \rightarrow \{1,...,n\}$, called a layout of $G$, such that for every edge $uv \in E(G)$, $|f(u) - f(v)| \leq b$. In…

Data Structures and Algorithms · Computer Science 2014-05-01 Markus Sortland Dregi , Daniel Lokshtanov

We introduce a new bilevel version of the classic shortest path problem and completely characterize its computational complexity with respect to several problem variants. In our problem, the leader and the follower each control a subset of…

Data Structures and Algorithms · Computer Science 2026-02-19 Dorothee Henke , Lasse Wulf

A k-queue layout is a special type of a linear layout, in which the linear order avoids (k+1)-rainbows, i.e., k+1 independent edges that pairwise form a nested pair. The optimization goal is to determine the queue number of a graph, i.e.,…

Data Structures and Algorithms · Computer Science 2021-08-06 Michael A. Bekos , Martin Gronemann , Chrysanthi N. Raftopoulou

Determining whether there exists a graph such that its crossing number and pair crossing number are distinct is an important open problem in geometric graph theory. We show that $\textit{cr}(G)=O(\mathop{\mathrm{pcr}}(G)^{3/2})$ for every…

Combinatorics · Mathematics 2022-11-17 Oriol Solé Pi

In this paper we give an overview of the graph invariants queue number and stack number (the latter also called the page number or book thickness). Due to their similarity, it has been studied for a long time, whether one of them is bounded…

Discrete Mathematics · Computer Science 2023-05-18 Adam Straka

We establish a list of characterizations of bounded twin-width for hereditary, totally ordered binary structures. This has several consequences. First, it allows us to show that a (hereditary) class of matrices over a finite alphabet either…

The \emph{thinness} of a graph is a width parameter that generalizes some properties of interval graphs, which are exactly the graphs of thinness one. Graphs with thinness at most two include, for example, bipartite convex graphs. Many…

Discrete Mathematics · Computer Science 2023-10-06 Flavia Bonomo-Braberman , Gastón Abel Brito

We consider a bi-criteria generalization of the pathwidth problem, where, for given integers $k,l$ and a graph $G$, we ask whether there exists a path decomposition $\cP$ of $G$ such that the width of $\cP$ is at most $k$ and the number of…

Data Structures and Algorithms · Computer Science 2021-03-05 Dariusz Dereniowski , Wieslaw Kubiak , Yori Zwols

A graph G is {\xi}-nearly planar if it can be embedded in the sphere so that each of its edges is crossed at most {\xi} times. The family of {\xi}-nearly planar graphs is widely extending the notion of planarity. We introduce an alternative…

Combinatorics · Mathematics 2013-11-04 Alexander Grigoriev , Athanassios Koutsonas , Dimitrios M. Thilikos

We construct a family of planar graphs $\{G_n\}_{n\geq 4}$, where $G_n$ has $n$ vertices including a source vertex $s$ and a sink vertex $t$, and edge weights that change linearly with a parameter $\lambda$ such that, as $\lambda$ varies in…

Computational Complexity · Computer Science 2019-06-20 Kshitij Gajjar , Jaikumar Radhakrishnan

The twin-width of a graph measures its distance to co-graphs and generalizes classical width concepts such as tree-width or rank-width. Since its introduction in 2020 (Bonnet et. al. 2020), a mass of new results has appeared relating twin…

Combinatorics · Mathematics 2024-11-21 Irene Heinrich , Simon Raßmann

We propose a new exact approach to the generalized graph layering problem that is based on a particular quadratic assignment formulation. It expresses, in a natural way, the associated layout restrictions and several possible objectives,…

Data Structures and Algorithms · Computer Science 2019-08-13 Sven Mallach

Birmele [J. Graph Theory, 2003] proved that every graph with circumference t has treewidth at most t-1. Under the additional assumption of 2-connectivity, such graphs have bounded pathwidth, which is a qualitatively stronger result.…

Combinatorics · Mathematics 2015-06-08 Emily A. Marshall , David R. Wood

We say that a graph $G$ is $(2,m)$-linked if, for any distinct vertices $a_1,\ldots, a_m, b_1,b_2$ in $G$, there exist vertex disjoint connected subgraphs $A,B$ of $G$ such that $\{a_1, \ldots, a_m\}$ is contained in $A$ and $\{b_1,b_2\}$…

Combinatorics · Mathematics 2023-03-23 Xiying Du , Yanjia Li , Shijie Xie , Xingxing Yu

Xiong and Liu [L. Xiong and Z. Liu, Hamiltonian iterated line graphs, Discrete Math. 256 (2002) 407-422] gave a characterization of the graphs $G$ for which the $n$-th iterated line graph $L^n(G)$ is hamiltonian, for $n\ge2$. In this paper,…

Combinatorics · Mathematics 2021-01-01 Zhaohong Nou , Liming Xiong , Weihua Yang

We investigate relations between different width parameters of graphs, in particular balanced separator number, treewidth, and cycle rank. Our main result states that a graph with balanced separator number k has treewidth at least k but…

Discrete Mathematics · Computer Science 2015-03-17 Hermann Gruber

Motivated by recent extensive studies on Wenger graphs, we introduce a new infinite class of bipartite graphs of the similar type, called linearized Wenger graphs. The spectrum, diameter and girth of these linearized Wenger graphs are…

Combinatorics · Mathematics 2014-12-02 Xiwang Cao , Mei Lu , Daqing Wan , Li-Ping Wang , Qiang Wang

The study of the graph diameter of polytopes is a classical open problem in polyhedral geometry and the theory of linear optimization. In this paper we continue the investigation initiated in [4] by introducing a vast hierarchy of…

Combinatorics · Mathematics 2014-11-27 Steffen Borgwardt , Jesús A. De Loera , Elisabeth Finhold

The {\em circumference} of a graph $G$ with at least one cycle is the length of a longest cycle in $G$. A classic result of Birmel\'e (2003) states that the treewidth of $G$ is at most its circumference minus $1$. In case $G$ is…

Combinatorics · Mathematics 2024-03-05 Marcin Briański , Gwenaël Joret , Michał T. Seweryn