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There is a graph reduction system so that every optimal 1-planar graph can be reduced to an irreducible extended wheel graph, provided the reductions are applied such that the given graph class is preserved. A graph is optimal 1-planar if…

Computational Geometry · Computer Science 2016-10-28 Franz J. Brandenburg

We provide a simple new randomized contraction approach to the global minimum cut problem for simple undirected graphs. The contractions exploit 2-out edge sampling from each vertex rather than the standard uniform edge sampling. We…

Data Structures and Algorithms · Computer Science 2019-09-04 Mohsen Ghaffari , Krzysztof Nowicki , Mikkel Thorup

By a poly-line drawing of a graph G on n vertices we understand a drawing of G in the plane such that each edge is represented by a polygonal arc joining its two respective vertices. We call a turning point of a polygonal arc the bend. We…

Combinatorics · Mathematics 2010-02-15 Radoslav Fulek , Balázs Keszegh , Filip Morić

This paper studies optimal-area visibility representations of $n$-vertex outer-1-plane graphs, i.e. graphs with a given embedding where all vertices are on the boundary of the outer face and each edge is crossed at most once. We show that…

Computational Geometry · Computer Science 2021-08-27 Therese Biedl , Giuseppe Liotta , Jayson Lynch , Fabrizio Montecchiani

In any attempt at designing an efficient algorithm for the minimum vertex cover problem, obtaining good upper and lower bounds for the vertex cover number could be crucial. In this article we present a modified greedy algorithm of…

Combinatorics · Mathematics 2019-01-04 R. Dharmarajan , D. Ramachandran

The algorithm of Gutwenger et al. to insert an edge $e$ in linear time into a planar graph $G$ with a minimal number of crossings on $e$, is a helpful tool for designing heuristics that minimize edge crossings in drawings of general graphs.…

Data Structures and Algorithms · Computer Science 2018-08-01 Marcel Radermacher , Ignaz Rutter

A \emph{book-embedding} of a graph $G$ is an embedding of vertices of $G$ along the spine of a book, and edges of $G$ on the pages so that no two edges on the same page intersect. the minimum number of pages in which a graph can be embedded…

Combinatorics · Mathematics 2018-01-23 Xiaxia Guan , Weihua Yang

We significantly improve known time bounds for solving the minimum cut problem on undirected graphs. We use a ``semi-duality'' between minimum cuts and maximum spanning tree packings combined with our previously developed random sampling…

Data Structures and Algorithms · Computer Science 2007-05-23 David R. Karger

The minimum cut problem for an undirected edge-weighted graph asks us to divide its set of nodes into two blocks while minimizing the weight sum of the cut edges. Here, we introduce a linear-time algorithm to compute near-minimum cuts. Our…

Data Structures and Algorithms · Computer Science 2019-06-05 Monika Henzinger , Alexander Noe , Christian Schulz , Darren Strash

We study the problem of computing the minimum area triangle that circumscribes a given $n$-sided convex polygon touching edge-to-edge. In other words, we compute the minimum area triangle that is the intersection of 3 half-planes out of $n$…

Computational Geometry · Computer Science 2022-08-15 Kai Jin , Zhiyi Huang

We give the first almost-linear time algorithm for computing the \emph{maximal $k$-edge-connected subgraphs} of an undirected unweighted graph for any constant $k$. More specifically, given an $n$-vertex $m$-edge graph $G=(V,E)$ and a…

Data Structures and Algorithms · Computer Science 2023-07-04 Thatchaphol Saranurak , Wuwei Yuan

We describe a polynomial time algorithm that takes as input a polygon with axis-parallel sides but irrational vertex coordinates, and outputs a set of as few rectangles as possible into which it can be dissected by axis-parallel cuts and…

Computational Geometry · Computer Science 2025-01-08 David Eppstein

In the minimum planarization problem, given some $n$-vertex graph, the goal is to find a set of vertices of minimum cardinality whose removal leaves a planar graph. This is a fundamental problem in topological graph theory. We present a…

Data Structures and Algorithms · Computer Science 2017-08-17 Ken-ichi Kawarabayashi , Anastasios Sidiropoulos

We investigate the problem of partitioning a rectilinear polygon $P$ with $n$ vertices and no holes % with no holes into rectangles using disjoint line segments drawn inside $P$ under two optimality criteria. In the minimum ink partition,…

Computational Geometry · Computer Science 2021-11-04 Hwi Kim , Jaegun Lee , Hee-Kap Ahn

We establish that a simple polynomial-time algorithm that we call reweighted spectral partitioning obtains small 2/3-balanced vertex-separators for a number of graph classes, including $O(\sqrt{n})$-sized separators for planar graphs,…

Data Structures and Algorithms · Computer Science 2025-11-18 Jack Spalding-Jamieson

We consider the embeddability problem of a graph G into a two-dimensional simplicial complex C: Given G and C, decide whether G admits a topological embedding into C. The problem is NP-hard, even in the restricted case where C is…

Computational Geometry · Computer Science 2025-11-13 Éric Colin de Verdière , Thomas Magnard

Given an undirected edge-weighted graph $G=(V,E)$ with $m$ edges and $n$ vertices, the minimum cut problem asks to find a subset of vertices $S$ such that the total weight of all edges between $S$ and $V \setminus S$ is minimized. Karger's…

Data Structures and Algorithms · Computer Science 2020-08-07 Paweł Gawrychowski , Shay Mozes , Oren Weimann

We show how to preprocess a weighted undirected $n$-vertex planar graph in $\tilde O(n^{4/3})$ time, such that the distance between any pair of vertices can then be reported in $\tilde O(1)$ time. This improves the previous $\tilde…

Data Structures and Algorithms · Computer Science 2025-03-25 Itai Boneh , Shay Golan , Shay Mozes , Daniel Prigan , Oren Weimann

On sparse graphs, Roditty and Williams [2013] proved that no $O(n^{2-\varepsilon})$-time algorithm achieves an approximation factor smaller than $\frac{3}{2}$ for the diameter problem unless SETH fails. In this article, we solve an open…

Data Structures and Algorithms · Computer Science 2023-01-24 Pierre Bergé , Guillaume Ducoffe , Michel Habib

Let G=(V,E) be a graph with f:V\to Z_+ a function assigning degree bounds to vertices. We present the first efficient algebraic algorithm to find an f-factor. The time is \tilde{O}(f(V)^{\omega}). More generally for graphs with integral…

Data Structures and Algorithms · Computer Science 2013-04-26 Harold N. Gabow , Piotr Sankowski