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We continue the study of the area requirement of convex straight-line grid drawings of 3-connected plane graphs, which has been intensively investigated in the last decades. Motivated by applications, such as graph editors, we additionally…

Data Structures and Algorithms · Computer Science 2022-05-10 Michael A. Bekos , Martin Gronemann , Fabrizio Montecchiani , Antonios Symvonis

We study planar straight-line drawings of graphs that minimize the ratio between the length of the longest and the shortest edge. We answer a question of Lazard et al. [Theor. Comput. Sci. 770 (2019), 88--94] and, for any given constant…

Computational Geometry · Computer Science 2020-08-21 Václav Blažej , Jiří Fiala , Giuseppe Liotta

An adjacency-crossing graph is a graph that can be drawn such that every two edges that cross the same edge share a common endpoint. We show that the number of edges in an $n$-vertex adjacency-crossing graph is at most $5n-10$. If we…

Combinatorics · Mathematics 2023-09-14 Eyal Ackerman , Balázs Keszegh

The visualization of any graph plays important role in various aspects, such as graph drawing software. Complex systems (like large databases or networks) that have a graph structure should be properly visualized in order to avoid…

Data Structures and Algorithms · Computer Science 2010-12-14 Nicolaos Matsakis

We study the algorithmic problem of computing drawings of graphs in which $(i)$ each vertex is a disk with fixed radius $\rho$, $(ii)$ each edge is a straight-line segment connecting the centers of the two disks representing its…

Data Structures and Algorithms · Computer Science 2021-05-06 Michael A. Bekos , Martin Gronemann , Fabrizio Montecchiani , Dömötör Pálvölgyi , Antonios Symvonis , Leonidas Theocharous

The geometric thickness of a graph G is the minimum integer k such that there is a straight line drawing of G with its edge set partitioned into k plane subgraphs. Eppstein [Separating thickness from geometric thickness. In: Towards a…

Combinatorics · Mathematics 2007-05-23 Janos Barat , Jiri Matousek , David R. Wood

A bisection of a graph is a bipartition of its vertex set in which the number of vertices in the two parts differ by at most 1, and its size is the number of edges which go across the two parts. In this paper, motivated by several questions…

Combinatorics · Mathematics 2013-05-29 Choongbum Lee , Po-Shen Loh , Benny Sudakov

We show that the 1-planar slope number of 3-connected cubic 1-planar graphs is at most 4 when edges are drawn as polygonal curves with at most 1 bend each. This bound is obtained by drawings whose vertex and crossing resolution is at least…

Computational Geometry · Computer Science 2018-08-28 Philipp Kindermann , Fabrizio Montecchiani , Lena Schlipf , André Schulz

Recent cognitive experiments have shown that the negative impact of an edge crossing on the human understanding of a graph drawing, tends to be eliminated in the case where the crossing angles are greater than 70 degrees. This motivated the…

Data Structures and Algorithms · Computer Science 2015-05-20 Evmorfia N. Argyriou , Michael A. Bekos , Antonios Symvonis

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

A drawing of a graph is $k$-plane if every edge contains at most $k$ crossings. A $k$-plane drawing is saturated if we cannot add any edge so that the drawing remains $k$-plane. It is well-known that saturated $0$-plane drawings, that is,…

Combinatorics · Mathematics 2023-08-30 János Barát , Géza Tóth

We show that any outerplanar graph admits a planar straightline drawing such that the length ratio of the longest to the shortest edges is strictly less than 2. This result is tight in the sense that for any $\epsilon > 0$ there are…

Computational Geometry · Computer Science 2017-09-04 Sylvain Lazard , William Lenhart , Giuseppe Liotta

We investigate straight-line drawings of topological graphs that consist of a planar graph plus one edge, also called almost-planar graphs. We present a characterization of such graphs that admit a straight-line drawing. The…

Computational Geometry · Computer Science 2015-07-01 Peter Eades , Seok-Hee Hong , Giuseppe Liotta , Naoki Katoh , Sheung-Hung Poon

The inverse degree of a graph is the sum of the reciprocals of the degrees of its vertices. We prove that in any connected planar graph, the diameter is at most 5/2 times the inverse degree, and that this ratio is tight. To develop a…

Combinatorics · Mathematics 2010-06-15 Radoslav Fulek , Filip Morić , David Pritchard

We consider upward-planar layered drawings of directed graphs, i.e., crossing-free drawings in which each edge is drawn as a y-monotone curve going upward from its tail to its head, and the y-coordinates of the vertices are integers. The…

Computational Geometry · Computer Science 2026-05-04 Patrizio Angelini , Sabine Cornelsen , Giordano Da Lozzo , Fabrizio Frati , Philipp Kindermann , Ignaz Rutter , Johannes Zink

A straight-line drawing of a graph $G$ is a mapping which assigns to each vertex a point in the plane and to each edge a straight-line segment connecting the corresponding two points. The rectilinear crossing number of a graph $G$,…

Computational Geometry · Computer Science 2016-09-08 Jacob Fox , Janos Pach , Andrew Suk

A rectangular drawing of a planar graph $G$ is a planar drawing of $G$ in which vertices are mapped to grid points, edges are mapped to horizontal and vertical straight-line segments, and faces are drawn as rectangles. Sometimes this latter…

Computational Geometry · Computer Science 2024-07-25 Carlos Alegria , Giordano Da Lozzo , Giuseppe Di Battista , Fabrizio Frati , Fabrizio Grosso , Maurizio Patrignani

In a RAC drawing of a graph, vertices are represented by points in the plane, adjacent vertices are connected by line segments, and crossings must form right angles. Graphs that admit such drawings are RAC graphs. RAC graphs are…

Computational Geometry · Computer Science 2020-07-10 Steven Chaplick , Henry Förster , Myroslav Kryven , Alexander Wolff

An almost self-centered graph is a connected graph of order $n$ with exactly $n-2$ central vertices, and an almost peripheral graph is a connected graph of order $n$ with exactly $n-1$ peripheral vertices. We determine (1) the maximum girth…

Combinatorics · Mathematics 2021-06-24 Yanan Hu , Xingzhi Zhan

A drawing of a graph in the plane is a thrackle if every pair of edges intersects exactly once, either at a common vertex or at a proper crossing. Conway's conjecture states that a thrackle has at most as many edges as vertices. In this…

Discrete Mathematics · Computer Science 2019-09-18 Oswin Aichholzer , Linda Kleist , Boris Klemz , Felix Schröder , Birgit Vogtenhuber