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A string graph is an intersection graph of curves in the plane. A $k$-string graph is a graph with a string representation in which every pair of curves intersects in at most $k$ points. We introduce the class of $(=k)$-string graphs as a…

Combinatorics · Mathematics 2023-08-31 Petr Chmel , Vít Jelínek

Consider two horizontal lines in the plane. A pair of a point on the top line and an interval on the bottom line defines a triangle between two lines. The intersection graph of such triangles is called a simple-triangle graph. This paper…

Discrete Mathematics · Computer Science 2016-11-29 Asahi Takaoka

A graph $G$ is a non-separating planar graph if there is a drawing $D$ of $G$ on the plane such that (1) no two edges cross each other in $D$ and (2) for any cycle $C$ in $D$, any two vertices not in $C$ are on the same side of $C$ in $D$.…

Combinatorics · Mathematics 2019-07-24 Hooman R. Dehkordi , Graham Farr

The Burling sequence is a sequence of triangle-free graphs of increasing chromatic number. Each of them is isomorphic to the intersection graph of a set of axis-parallel boxes in $R^3$. These graphs were also proved to have other…

Combinatorics · Mathematics 2023-09-08 Pegah Pournajafi , Nicolas Trotignon

We consider drawings of graphs that contain dense subgraphs. We introduce intersection-link representations for such graphs, in which each vertex $u$ is represented by a geometric object $R(u)$ and in which each edge $(u,v)$ is represented…

Data Structures and Algorithms · Computer Science 2015-09-01 Patrizio Angelini , Giordano Da Lozzo , Giuseppe Di Battista , Fabrizio Frati , Maurizio Patrignani , Ignaz Rutter

If we parameterize the positions of all vertices of a given graph in the plane such that distances between adjacent vertices are fixed, we obtain a moving graph. An L-linkage is a realization of a moving graph in 3D-space, by representing…

Combinatorics · Mathematics 2021-05-06 Jiayue Qi

In this paper we continue the study of the edge intersection graphs of one (or zero) bend paths on a rectangular grid. That is, the edge intersection graphs where each vertex is represented by one of the following shapes:…

Discrete Mathematics · Computer Science 2015-10-06 Kathie Cameron , Steven Chaplick , Chính T. Hoàng

Median graphs are connected graphs in which for all three vertices there is a unique vertex that belongs to shortest paths between each pair of these three vertices. In this paper we provide several novel characterizations of planar median…

Combinatorics · Mathematics 2021-10-19 Carsten R. Seemann , Vincent Moulton , Peter F. Stadler , Marc Hellmuth

A square-contact representation of a planar graph $G=(V,E)$ maps vertices in $V$ to interior-disjoint axis-aligned squares in the plane and edges in $E$ to adjacencies between the sides of the corresponding squares. In this paper, we study…

Computational Geometry · Computer Science 2017-10-03 Giordano Da Lozzo , William E. Devanny , David Eppstein , Timothy Johnson

A segment representation of a graph is an assignment of line segments in 2D to the vertices in such a way that two segments intersect if and only if the corresponding vertices are adjacent. Not all graphs have such segment representations,…

Computational Geometry · Computer Science 2018-10-17 Therese Biedl

We consider arrangements of axis-aligned rectangles in the plane. A geometric arrangement specifies the coordinates of all rectangles, while a combinatorial arrangement specifies only the respective intersection type in which each pair of…

Computational Geometry · Computer Science 2015-09-03 Jonathan Klawitter , Martin Nöllenburg , Torsten Ueckerdt

For a set of non-negative integers $L$, the $L$-intersection number of a graph is the smallest number $l$ for which there is an assignment on the vertices to subsets $A_v \subseteq \{1,\dots, l\}$, such that every two vertices $u,v$ are…

Combinatorics · Mathematics 2013-08-22 Zeinab Maleki , Behnaz Omoomi

We consider several classes of intersection graphs of line segments in the plane and prove new equality and separation results between those classes. In particular, we show that: (1) intersection graphs of grounded segments and intersection…

Discrete Mathematics · Computer Science 2016-12-13 Jean Cardinal , Stefan Felsner , Tillmann Miltzow , Casey Tompkins , Birgit Vogtenhuber

In an $\mathsf{L}$-embedding of a graph, each vertex is represented by an $\mathsf{L}$-segment, and two segments intersect each other if and only if the corresponding vertices are adjacent in the graph. If the corner of each…

Computational Geometry · Computer Science 2017-03-07 Abu Reyan Ahmed , Felice De Luca , Sabin Devkota , Alon Efrat , Md Iqbal Hossain , Stephen Kobourov , Jixian Li , Sammi Abida Salma , Eric Welch

Intersection graphs are very important in both theoretical as well as application point of view. Depending on the geometrical representation, different type of intersection graphs are defined. Among them interval, circular-arc, permutation,…

Discrete Mathematics · Computer Science 2014-04-23 Madhumangal Pal

Let $m, n > 1$ be two integers, and $\mathbb{Z}_n$ be a $\mathbb{Z}_m$-module. Let $I(\mathbb{Z}_m)^*$ be the set of all non- zero proper ideals of $\mathbb{Z}_m$. The $\mathbb{Z}_n$-intersection graph of $\mathbb{Z}_m$, denoted by…

Commutative Algebra · Mathematics 2017-12-20 S. Khojasteh

Ray intersection graphs are intersection graphs of rays, or halflines, in the plane. We show that any planar graph has an even subdivision whose complement is a ray intersection graph. The construction can be done in polynomial time and…

Computational Geometry · Computer Science 2011-11-28 Sergio Cabello , Jean Cardinal , Stefan Langerman

Let $G$ be a group. The intersection graph of subgroups of $G$, denoted by $\mathscr{I}(G)$, is a graph with all the proper subgroups of $G$ as its vertices and two distinct vertices in $\mathscr{I}(G)$ are adjacent if and only if the…

Group Theory · Mathematics 2015-06-03 R. Rajkumar , P. Devi

Planar graphs can be represented as intersection graphs of different types of geometric objects in the plane, e.g., circles (Koebe, 1936), line segments (Chalopin \& Gon{\c{c}}alves, 2009), \textsc{L}-shapes (Gon{\c{c}}alves et al, 2018).…

Computational Geometry · Computer Science 2021-06-03 Dibyayan Chakraborty , Kshitij Gajjar

Laman graphs naturally arise in structural mechanics and rigidity theory. Specifically, they characterize minimally rigid planar bar-and-joint systems which are frequently needed in robotics, as well as in molecular chemistry and polymer…

Combinatorics · Mathematics 2012-10-01 Stephen Kobourov , Torsten Ueckerdt , Kevin Verbeek