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The partial representation extension problem is a recently introduced generalization of the recognition problem. A circle graph is an intersection graph of chords of a circle. We study the partial representation extension problem for circle…

Discrete Mathematics · Computer Science 2017-10-03 Steven Chaplick , Radoslav Fulek , Pavel Klavík

Let A_1,...,A_k be a collection of families of subsets of an n-element set. We say that this collection is cross-intersecting if for any i,j in [k] with i not equal to j, A in A_i and B in A_j implies that the intersection of A and B is…

Combinatorics · Mathematics 2010-10-06 Vikram Kamat

The chordal ring (CR) graphs are a well-known family of graphs used to model some interconnection networks for computer systems in which all nodes are in a cycle. Generalizing the CR graphs, in this paper, we introduce the families of…

Combinatorics · Mathematics 2024-09-04 M. A. Reyes , C. Dalfó , M. A. Fiol

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

We study graph classes modeled by families of non-crossing (NC) connected sets. Two classic graph classes in this context are disk graphs and proper interval graphs. We focus on the cases when the sets are paths and the host is a tree…

Discrete Mathematics · Computer Science 2020-08-18 Steven Chaplick

In the Segment Intersection Graph Representation Problem, we want to represent the vertices of a graph as straight line segments in the plane such that two segments cross if and only if there is an edge between the corresponding vertices.…

Computational Geometry · Computer Science 2025-02-25 Simon D. Fink , Matthias Pfretzschner , Peter Stumpf

An \emph{outer-string representation} of a graph $G$ is an intersection representation of $G$ where vertices are represented by curves (strings) inside the unit disk and each curve has exactly one endpoint on the boundary of the unit disk…

Combinatorics · Mathematics 2026-05-18 Todor Antić , Vít Jelínek , Jan Kratochvíl , Peter Stumpf

Strongly chordal graphs are a subclass of chordal graphs. Farber also established a number of different characterisations for this class of graphs. These include an intersection graph characterisation that is analogous to a similar…

Data Structures and Algorithms · Computer Science 2019-09-06 Md. Zamilur Rahman , Asish Mukhopadhyay

A graph $G$ with vertex set $\{v_1,v_2,\ldots,v_n\}$ is an intersection graph of segments if there are segments $s_1,\ldots,s_n$ in the plane such that $s_i$ and $s_j$ have a common point if and only if $\{v_i,v_j\}$ is an edge of~$G$. In…

Computational Geometry · Computer Science 2014-06-11 Jiri Matousek

Let $G=(V,E)$ be an undirected graph without loops and multiple edges. A subset $C\subseteq V$ is called \emph{identifying} if for every vertex $x\in V$ the intersection of $C$ and the closed neighbourhood of $x$ is nonempty, and these…

Combinatorics · Mathematics 2009-02-04 Sylvain Gravier , Svante Janson , Tero Laihonen , Sanna Ranto

In this article we introduce and study the intersection graph of graded ideals of graded rings. The intersection graph of $G-$graded ideals of a graded ring $(R,G)$ is a simple graph, denoted by $Gr_G(R)$, whose vertices are the nontrivial…

Rings and Algebras · Mathematics 2020-08-11 T. Alraqad , H. Saber , R. Abu-Dawwas

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

A pseudoline is a homeomorphic image of the real line in the plane so that its complement is disconnected. An arrangement of pseudolines is a set of pseudolines in which every two cross exactly once. A drawing of a graph is pseudolinear if…

Combinatorics · Mathematics 2018-04-26 Alan Arroyo , Julien Bensmail , R. Bruce Richter

We analyse properties of geometric intersection graphs to show the strict containment between some natural classes of geometric intersection graphs. In particular, we show the following properties: - A graph $G$ is outerplanar if and only…

Combinatorics · Mathematics 2017-02-02 Sergio Cabello , Miha Jejčič

Let H, K be subgroups of G. We investigate the intersection properties of left and right cosets of these subgroups.

Group Theory · Mathematics 2016-10-21 Jack Button , Maurice Chiodo , Mariano Zeron-Medina Laris

In his Ph.D. thesis, Farber proved that every strongly chordal graph can be represented as intersection graph of subtrees of a weighted tree, and these subtrees are ``compatible''. Moreover, this is an equivalent characterization of…

Combinatorics · Mathematics 2025-03-13 Therese Biedl

We study limits of convergent sequences of string graphs, that is, graphs with an intersection representation consisting of curves in the plane. We use these results to study the limiting behavior of a sequence of random string graphs. We…

Combinatorics · Mathematics 2014-03-13 Svante Janson , Andrew J. Uzzell

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

Deciding whether a collection of unrooted trees is compatible is a fundamental problem in phylogenetics. Two different graph-theoretic characterizations of tree compatibility have recently been proposed. In one of these, tree compatibility…

Discrete Mathematics · Computer Science 2012-10-16 Sudheer Vakati , David Fernández-Baca

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