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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

Plotkin, Rao, and Smith (SODA'97) showed that any graph with $m$ edges and $n$ vertices that excludes $K_h$ as a depth $O(\ell\log n)$-minor has a separator of size $O(n/\ell + \ell h^2\log n)$ and that such a separator can be found in…

Data Structures and Algorithms · Computer Science 2014-07-28 Christian Wulff-Nilsen

The hyperbolicity of a graph, informally, measures how close a graph is (metrically) to a tree. Hence, it is intuitively similar to treewidth, but the measures are formally incomparable. Motivated by the broad study of algorithms and…

Data Structures and Algorithms · Computer Science 2023-10-18 Sándor Kisfaludi-Bak , Jana Masaříková , Erik Jan van Leeuwen , Bartosz Walczak , Karol Węgrzycki

Partitioning a graph using graph separators, and particularly clique separators, are well-known techniques to decompose a graph into smaller units which can be treated independently. It was previously known that the treewidth was bounded…

Discrete Mathematics · Computer Science 2019-09-09 Boi Faltings , Martin Charles Golumbic

We show how to test whether a graph with n vertices and m edges is a partial cube, and if so how to find a distance-preserving embedding of the graph into a hypercube, in the near-optimal time bound O(n^2), improving previous O(nm)-time…

Data Structures and Algorithms · Computer Science 2011-07-21 David Eppstein

The visual complexity of a graph drawing can be measured by the number of geometric objects used for the representation of its elements. In this paper, we study planar graph drawings where edges are represented by few segments. In such a…

Computational Geometry · Computer Science 2019-08-06 Philipp Kindermann , Tamara Mchedlidze , Thomas Schneck , Antonios Symvonis

In the k-Apex problem the task is to find at most k vertices whose deletion makes the given graph planar. The graphs for which there exists a solution form a minor closed class of graphs, hence by the deep results of Robertson and Seymour,…

Data Structures and Algorithms · Computer Science 2008-12-31 Dániel Marx , Ildikó Schlotter

We show that there exists an adjacency labelling scheme for planar graphs where each vertex of an $n$-vertex planar graph $G$ is assigned a $(1+o(1))\log_2 n$-bit label and the labels of two vertices $u$ and $v$ are sufficient to determine…

Data Structures and Algorithms · Computer Science 2021-12-03 Vida Dujmović , Louis Esperet , Gwenaël Joret , Cyril Gavoille , Piotr Micek , Pat Morin

Temporal graphs are graphs with time-stamped edges. We study the problem of finding a small vertex set (the separator) with respect to two designated terminal vertices such that the removal of the set eliminates all temporal paths…

Data Structures and Algorithms · Computer Science 2018-07-26 Philipp Zschoche , Till Fluschnik , Hendrik Molter , Rolf Niedermeier

We consider the largest number of minimal separators a graph on n vertices can have at most. We give a new proof that this number is in $O( ((1+\sqrt{5})/2)^n n )$. We prove that this number is in $\omega( 1.4521^n )$, improving on the…

Data Structures and Algorithms · Computer Science 2015-04-03 Serge Gaspers , Simon Mackenzie

We show that the edges of any planar graph of maximum degree at most $9$ can be partitioned into $4$ linear forests and a matching. Combined with known results, this implies that the edges of any planar graph $G$ of odd maximum degree…

Combinatorics · Mathematics 2023-02-28 Marthe Bonamy , Jadwiga Czyżewska , Łukasz Kowalik , Michał Pilipczuk

We show that for every integer $n\geq 1$ there exists a graph $G_n$ with $(1+o(1))n$ vertices and $n^{1 + o(1)}$ edges such that every $n$-vertex planar graph is isomorphic to a subgraph of $G_n$. The best previous bound on the number of…

Combinatorics · Mathematics 2023-10-09 Louis Esperet , Gwenaël Joret , Pat Morin

The Planar Graph Metric Compression Problem is to compactly encode the distances among $k$ nodes in a planar graph of size $n$. Two na\"ive solutions are to store the graph using $O(n)$ bits, or to explicitly store the distance matrix with…

Data Structures and Algorithms · Computer Science 2017-03-16 Amir Abboud , Pawel Gawrychowski , Shay Mozes , Oren Weimann

Tensor networks have been an important concept and technique in many research areas, such as quantum computation and machine learning. We study the exponential complexity of contracting tensor networks on two special graph structures:…

Computational Complexity · Computer Science 2023-07-06 Liu Ying

It is known that every proper minor-closed class of graphs has bounded stack-number (a.k.a. book thickness and page number). While this includes notable graph families such as planar graphs and graphs of bounded genus, many other graph…

Computational Geometry · Computer Science 2016-08-24 Vida Dujmović , Fabrizio Frati

A classical result of Robertson and Seymour (1986) states that the treewidth of a graph is linearly tied to its separation number: the smallest integer $k$ such that, for every weighting of the vertices, the graph admits a balanced…

Combinatorics · Mathematics 2025-07-23 Maria Chudnovsky , Robert Hickingbotham

We study algorithms for drawing planar graphs and 1-planar graphs using cubic B\'ezier curves with bounded curvature. We show that any n-vertex 1-planar graph has a 1-planar RAC drawing using a single cubic B\'ezier curve per edge, and this…

Computational Geometry · Computer Science 2024-10-17 David Eppstein , Michael T. Goodrich , Abraham M. Illickan

We present $k^{O(k^2)} m$ time algorithms for various problems about decomposing a given undirected graph by edge cuts or vertex separators of size $<k$ into parts that are ``well-connected'' with respect to cuts or separators of size $<k$;…

Data Structures and Algorithms · Computer Science 2024-11-06 Tuukka Korhonen

A graph with n vertices is 1-planar if it can be drawn in the plane such that each edge is crossed at most once, and is optimal if it has the maximum of 4n-8 edges. We show that optimal 1-planar graphs can be recognized in linear time. Our…

Discrete Mathematics · Computer Science 2018-01-25 Franz J. Brandenburg

We prove the existence of optimal separators for intersection graphs of balls and spheres in any dimension $d$. One of our results is that if an intersection graph of $n$ spheres in $\mathbb{R}^d$ has $m$ edges, then it contains a balanced…

Computational Geometry · Computer Science 2026-03-24 Jacob Fox , Jonathan Tidor