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A planar Tangle is a smooth simple closed curve piecewise defined by quadrants of circles with constant curvature. We can enumerate Tangles by counting their dual graphs, which consist of a certain family of polysticks. The number of…

Combinatorics · Mathematics 2021-03-09 Douglas A. Torrance

A drawing of a graph is 1-planar if each edge participates in at most one crossing and adjacent edges do not cross. Up to symmetry, each crossing in a 1-planar drawing belongs to one out of six possible crossing types, where a type…

Data Structures and Algorithms · Computer Science 2025-11-20 Sergio Cabello , Alexander Dobler , Gašper Fijavž , Thekla Hamm , Mirko H. Wagner

It is shown that every $n$-vertex graph that admits a 2-bend RAC drawing in the plane, where the edges are polylines with two bends per edge and any pair of edges can only cross at a right angle, has at most $20n-24$ edges for $n\geq 3$.…

Discrete Mathematics · Computer Science 2024-11-05 Csaba D. Tóth

A 1-planar graph is a graph which has a drawing on the plane such that each edge is crossed at most once. If a 1-planar graph is drawn in that way, the drawing is called a {\it 1-plane graph}. A graph is maximal 1-plane (or 1-planar) if no…

Combinatorics · Mathematics 2025-05-01 Zhangdong Ouyang , Yuanqiu Huang , Licheng Zhang , Fengming Dong

A graph is $k$-planar $(k \geq 1)$ if it can be drawn in the plane such that no edge is crossed more than $k$ times. A graph is $k$-quasi planar $(k \geq 2)$ if it can be drawn in the plane with no $k$ pairwise crossing edges. The families…

In this paper, we introduce a new approach for drawing diagrams that have applications in software visualization. Our approach is to use a technique we call confluent drawing for visualizing non-planar diagrams in a planar way. This…

Computational Geometry · Computer Science 2007-05-23 Matthew Dickerson , David Eppstein , Michael T. Goodrich , Jeremy Meng

The k-planar graphs, which are (usually with small values of k such as 1, 2, 3) subject to recent intense research, admit a drawing in which edges are allowed to cross, but each one edge is allowed to carry at most k crossings. In recently…

Combinatorics · Mathematics 2024-10-02 Petr Hliněný , Lili Ködmön

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

A straight-line drawing of a graph is a monotone drawing if for each pair of vertices there is a path which is monotonically increasing in some direction, and it is called a strongly monotone drawing if the direction of monotonicity is…

Computational Geometry · Computer Science 2016-01-08 Stefan Felsner , Alexander Igamberdiev , Philipp Kindermann , Boris Klemz , Tamara Mchedlidze , Manfred Scheucher

A tangled-diagram over $[n]=\{1,...,n\}$ is a graph of degree less than two whose vertices $1,...,n$ are arranged in a horizontal line and whose arcs are drawn in the upper halfplane with a particular notion of crossings and nestings.…

Combinatorics · Mathematics 2011-11-10 William Y. C. Chen , Jing Qin , Christian M. Reidys

The well-known 1-2-3 Conjecture asserts that the edges of every graph without isolated edges can be weighted with $1$, $2$ and $3$ so that adjacent vertices receive distinct weighted degrees. This is open in general, while it is known to be…

Combinatorics · Mathematics 2019-12-19 Jakub Przybyło

We study the problem of embedding graphs in the plane as good geometric spanners. That is, for a graph $G$, the goal is to construct a straight-line drawing $\Gamma$ of $G$ in the plane such that, for any two vertices $u$ and $v$ of $G$,…

Data Structures and Algorithms · Computer Science 2020-02-14 Oswin Aichholzer , Manuel Borrazzo , Prosenjit Bose , Jean Cardinal , Fabrizio Frati , Pat Morin , Birgit Vogtenhuber

A geometric graph is a graph drawn in the plane so that its vertices and edges are represented by points in general position and straight line segments, respectively. A vertex of a geometric graph is called pointed if it lies outside of the…

Combinatorics · Mathematics 2022-08-31 Nikita Chernega , Alexandr Polyanskii , Rinat Sadykov

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

Given a planar graph $G$, we consider drawings of $G$ in the plane where edges are represented by straight line segments (which possibly intersect). Such a drawing is specified by an injective embedding $\pi$ of the vertex set of $G$ into…

Discrete Mathematics · Computer Science 2011-05-20 Mihyun Kang , Oleg Pikhurko , Alexander Ravsky , Mathias Schacht , Oleg Verbitsky

Consider a graph drawn on a surface (for example, the plane minus a finite set of obstacle points), possibly with crossings. We provide an algorithm to decide whether such a drawing can be untangled, namely, if one can slide the vertices…

Computational Geometry · Computer Science 2025-07-18 Éric Colin de Verdière , Vincent Despré , Loïc Dubois

A drawing of a graph is $k$-plane if no edge is crossed more than $k$ times. In this paper we study saturated $k$-plane drawings with few edges. This are $k$-plane drawings in which no edge can be added without violating $k$-planarity. For…

Computational Geometry · Computer Science 2021-08-31 Fabian Klute , Irene Parada

A graph on $n \ge 3$ vertices drawn in the plane such that each edge is crossed at most four times has at most $6(n-2)$ edges -- this result proven by Ackerman is outstanding in the literature of beyond-planar graphs with regard to its…

Combinatorics · Mathematics 2025-10-03 Aaron Büngener

A graph is 1-planar if it can be drawn on the plane so that each edge is crossed by at most one other edge. In this paper, we confirm the total-coloring conjecture for 1-planar graphs with maximum degree at least 13.

Combinatorics · Mathematics 2013-04-24 Xin Zhang , Jianfeng Hou , Guizhen Liu

By the theorem of Mantel $[5]$ it is known that a graph with $n$ vertices and $\lfloor \frac{n^{2}}{4} \rfloor+1$ edges must contain a triangle. A theorem of Erd\H{o}s gives a strengthening: there are not only one, but at least…

Combinatorics · Mathematics 2020-03-11 Chuanqi Xiao , Gyula O. H. Katona