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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

IC-planar graphs are those graphs that admit a drawing where no two crossed edges share an end-vertex and each edge is crossed at most once. They are a proper subfamily of the 1-planar graphs. Given an embedded IC-planar graph $G$ with $n$…

Computational Geometry · Computer Science 2016-07-19 Franz J. Brandenburg , Walter Didimo , William S. Evans , Philipp Kindermann , Giuseppe Liotta , Fabrizio Montecchiani

Graph pattern matching is often defined in terms of subgraph isomorphism, an NP-complete problem. To lower its complexity, various extensions of graph simulation have been considered instead. These extensions allow pattern matching to be…

Databases · Computer Science 2012-01-04 Shuai Ma , Yang Cao , Wenfei Fan , Jinpeng Huai , Tianyu Wo

A graph is geometric 1-planar if it admits a straight-line drawing where each edge is crossed at most once. We provide the first systematic study of the parameterized complexity of recognizing geometric 1-planar graphs. By substantially…

Computational Complexity · Computer Science 2026-02-11 Alexander Firbas

We investigate the problem of constructing planar drawings with few bends for two related problems, the partially embedded graph problem---to extend a straight-line planar drawing of a subgraph to a planar drawing of the whole graph---and…

Computational Geometry · Computer Science 2014-10-31 Timothy M. Chan , Fabrizio Frati , Carsten Gutwenger , Anna Lubiw , Petra Mutzel , Marcus Schaefer

A drawing of a graph is fan-planar if the edges intersecting a common edge $a$ share a vertex $A$ on the same side of $a$. More precisely, orienting $e$ arbitrarily and the other edges towards $A$ results in a consistent orientation of the…

Computational Geometry · Computer Science 2021-08-31 Boris Klemz , Kristin Knorr , Meghana M. Reddy , Felix Schröder

The topological symmetry group $\mathrm{TSG}(\Gamma)$ of an embedding $\Gamma$ of a graph in $S^3$ is the subgroup of the automorphism group of the graph which is induced by homeomorphisms of $(S^3,\Gamma)$. If we restrict to orientation…

Geometric Topology · Mathematics 2026-01-21 A. Álvarez , E. Flapan , M. Hunnell , J. Hutchens , E. Lawrence , P. Lewis , C. Price , R. Vanderpool

A drawing of a graph in the plane is called 1-planar if each edge is crossed at most once. A graph together with a 1-planar drawing is a 1-plane graph. A 1-plane graph $G$ with exactly $4|V (G)|-8$ edges is called optimal. The crossing…

Combinatorics · Mathematics 2025-08-15 Zhangdong Ouyang , Yuanqiu Huang , Licheng Zhang

In extension problems of partial graph drawings one is given an incomplete drawing of an input graph $G$ and is asked to complete the drawing while maintaining certain properties. A prominent area where such problems arise is that of…

Computational Geometry · Computer Science 2020-12-15 Robert Ganian , Thekla Hamm , Fabian Klute , Irene Parada , Birgit Vogtenhuber

It is well known that any graph admits a crossing-free straight-line drawing in $\mathbb{R}^3$ and that any planar graph admits the same even in $\mathbb{R}^2$. For a graph $G$ and $d \in \{2,3\}$, let $\rho^1_d(G)$ denote the smallest…

Computational Complexity · Computer Science 2024-03-04 Steven Chaplick , Krzysztof Fleszar , Fabian Lipp , Alexander Ravsky , Oleg Verbitsky , Alexander Wolff

The crossing angle of a straight-line drawing $\Gamma$ of a graph $G=(V, E)$ is the smallest angle between two crossing edges in $\Gamma$. Deciding whether a graph $G$ has a straight-line drawing with a crossing angle of $90^\circ$ is…

Computational Geometry · Computer Science 2018-08-01 Almut Demel , Dominik Dürrschnabel , Tamara Mchedlidze , Marcel Radermacher , Lasse Wulf

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

The thickness $\theta(G)$ of a graph $G$ is the minimum number of planar spanning subgraphs into which the graph $G$ can be decomposed. As a topological invariant of a graph, it is a measurement of the closeness to planarity of a graph, and…

Combinatorics · Mathematics 2012-02-01 Yan Yang , Xiangheng Kong

A drawing of a graph is said to be a {\em straight-line drawing} if the vertices of $G$ are represented by distinct points in the plane and every edge is represented by a straight-line segment connecting the corresponding pair of vertices…

Combinatorics · Mathematics 2012-03-08 V S Padmini Mukkamala

If $\Gamma$ is a graph for which every edge is in exactly one clique of order $\omega$, then one can form a new graph with vertex set equal to these cliques. This is a generalization of the line graph of $\Gamma$. We discover many general…

Combinatorics · Mathematics 2026-05-25 Connor Phillips

We study the following classes of beyond-planar graphs: 1-planar, IC-planar, and NIC-planar graphs. These are the graphs that admit a 1-planar, IC-planar, and NIC-planar drawing, respectively. A drawing of a graph is 1-planar if every edge…

Computational Geometry · Computer Science 2019-08-12 Steven Chaplick , Fabian Lipp , Alexander Wolff , Johannes Zink

Computing the crossing number of a graph is one of the most classical problems in computational geometry. Both it and numerous variations of the problem have been studied, and overcoming their frequent computational difficulty is an active…

Computational Geometry · Computer Science 2024-12-18 Thekla Hamm , Fabian Klute , Irene Parada

We consider the problem of untangling a given (non-planar) straight-line circular drawing $\delta_G$ of an outerplanar graph $G=(V, E)$ into a planar straight-line circular drawing by shifting a minimum number of vertices to a new position…

Computational Geometry · Computer Science 2021-12-21 Sujoy Bhore , Guangping Li , Martin Nöllenburg , Ignaz Rutter , Hsiang-Yun Wu

A graph is NIC-planar if it admits a drawing in the plane with at most one crossing per edge and such that two pairs of crossing edges share at most one common end vertex. NIC-planarity generalizes IC-planarity, which allows a vertex to be…

Discrete Mathematics · Computer Science 2017-11-06 Christian Bachmaier , Franz J. Brandenburg , Kathrin Hanauer , Daniel Neuwirth , Josef Reislhuber

We discuss the problem of embedding graphs in the plane with restrictions on the vertex mapping. In particular, we introduce a technique for drawing planar graphs with a fixed vertex mapping that bounds the number of times edges bend. An…

Computational Geometry · Computer Science 2012-06-05 Taylor Gordon