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One of the fundamental results in graph minor theory is that for every planar graph $H$, there is a minimum integer $f(H)$ such that graphs with no minor isomorphic to $H$ have treewidth at most $f(H)$. A lower bound for ${f(H)}$ can be…

Combinatorics · Mathematics 2026-01-16 J. Pascal Gollin , Kevin Hendrey , Sang-il Oum , Bruce Reed

We introduce the notion of \emph{bounded diameter arboricity}. Specifically, the \emph{diameter-$d$ arboricity} of a graph is the minimum number $k$ such that the edges of the graph can be partitioned into $k$ forests each of whose…

Combinatorics · Mathematics 2016-08-19 Martin Merker , Luke Postle

Let $n$, $k$ and $t$ be integers with $1\leq t< k \leq n$. The \emph{generalized Kneser graph} $K(n,k,t)$ is a graph whose vertices are the $k$-subsets of a fixed $n$-set, where two $k$-subsets $A$ and $B$ are adjacent if $|A\cap B|<t$. The…

Combinatorics · Mathematics 2021-08-10 Ke Liu , Mengyu Cao , Mei Lu

We consider straight-line outerplanar drawings of outerplanar graphs in which a small number of distinct edge slopes are used, that is, the segments representing edges are parallel to a small number of directions. We prove that $\Delta-1$…

Computational Geometry · Computer Science 2014-04-11 Kolja Knauer , Piotr Micek , Bartosz Walczak

We prove that the (divisorial) gonality of a finite connected graph is lower bounded by its treewidth. We show that equality holds for grid graphs and complete multipartite graphs. We prove that the treewidth lower bound also holds for…

Combinatorics · Mathematics 2022-01-04 Josse van Dobben de Bruyn , Dion Gijswijt

Tree-decompositions of graphs are of fundamental importance in structural and algorithmic graph theory. The main property of tree-decompositions is the width (the maximum size of a bag minus 1). We show that every graph has a…

Combinatorics · Mathematics 2026-05-08 David R. Wood

We study embeddings of graphs with bounded treewidth or bounded simple treewidth into the undirected graph underlying the directed product of two directed graphs. If the factors have bounded maximum indegrees, then the product graph has…

Combinatorics · Mathematics 2025-08-18 Kevin Hendrey , David R. Wood , Jung Hon Yip

A graph is called a $k$-planar unit distance graph if it can be drawn in the plane such that every edge is a unit line segment and is involved in at most $k$ crossings. We investigate $u_k(n)$, the maximum number of edges of such graphs on…

Combinatorics · Mathematics 2026-03-23 Panna Gehér , Dömötör Pálvölgyi , Dániel G. Simon , Géza Tóth

The $2$-layer drawing model is a well-established paradigm to visualize bipartite graphs. Several beyond-planar graph classes have been studied under this model. Surprisingly, however, the fundamental class of $k$-planar graphs has been…

Discrete Mathematics · Computer Science 2020-08-24 Patrizio Angelini , Giordano Da Lozzo , Henry Förster , Thomas Schneck

In this paper, we study some spanning trees with bounded degree and leaf degree from eigenvalues. For any integer $k\geq2$, a $k$-tree is a spanning tree in which every vertex has degree no more than $k$. Let $T$ be a spanning tree of a…

Combinatorics · Mathematics 2024-07-29 Chang Liu , Jianping Li

We establish relations between the bandwidth and the treewidth of bounded degree graphs G, and relate these parameters to the size of a separator of G as well as the size of an expanding subgraph of G. Our results imply that if one of these…

Combinatorics · Mathematics 2009-10-19 Julia Böttcher , Klaas P. Pruessmann , Anusch Taraz , Andreas Würfl

The proper thinness of a graph is an invariant that generalizes the concept of a proper interval graph. Every graph has a numerical value of proper thinness and the graphs with proper thinness~1 are exactly the proper interval graphs. A…

Combinatorics · Mathematics 2025-05-19 Flavia Bonomo-Braberman , Ignacio Maqueda , Nina Pardal

Let $V$ be an $n$-dimensional vector space over a finite field $\mathbb{F}_q$, where $q$ is a prime power. Define the \emph{generalized $q$-Kneser graph} $K_q(n,k,t)$ to be the graph whose vertices are the $k$-dimensional subspaces of $V$…

Combinatorics · Mathematics 2021-01-29 Mengyu Cao , Ke Liu , Mei Lu , Zequn Lv

The product dimension of a graph G is defined as the minimum natural number l such that G is an induced subgraph of a direct product of l complete graphs. In this paper we study the product dimension of forests, bounded treewidth graphs and…

Combinatorics · Mathematics 2012-09-12 L. Sunil Chandran , Rogers Mathew , Deepak Rajendraprasad , Roohani Sharma

Treewidth and Hadwiger number are two of the most important parameters in structural graph theory. This paper studies graph classes in which large treewidth implies the existence of a large complete graph minor. To formalise this, we say…

In this paper, we study the outerplanarity of planar graphs, i.e., the number of times that we must (in a planar embedding that we can initially freely choose) remove the outerface vertices until the graph is empty. It is well-known that…

Data Structures and Algorithms · Computer Science 2024-07-08 Therese Biedl , Debajyoti Mondal

Treewidth is an important graph invariant, relevant for both structural and algorithmic reasons. A necessary condition for a graph class to have bounded treewidth is the absence of large cliques. We study graph classes closed under taking…

Combinatorics · Mathematics 2021-11-09 Clément Dallard , Martin Milanič , Kenny Štorgel

We show that many graphs with bounded treewidth can be described as subgraphs of the strong product of a graph with smaller treewidth and a bounded-size complete graph. To this end, define the "underlying treewidth" of a graph class…

We study the notion of local treewidth in sparse random graphs: the maximum treewidth over all $k$-vertex subgraphs of an $n$-vertex graph. When $k$ is not too large, we give nearly tight bounds for this local treewidth parameter; we also…

Data Structures and Algorithms · Computer Science 2022-07-18 Hermish Mehta , Daniel Reichman

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