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We introduce the class of interval $H$-graphs, which is the generalization of interval graphs, particularly interval bigraphs. For a fixed graph $H$ with vertices $a_1,a_2,\dots,a_k$, we say that an input graph $G$ with given partition…

Discrete Mathematics · Computer Science 2025-03-04 Haiko Müller , Arash Rafiey

We initiate the study of a new parameterization of graph problems. In a multiple interval representation of a graph, each vertex is associated to at least one interval of the real line, with an edge between two vertices if and only if an…

Data Structures and Algorithms · Computer Science 2011-12-19 Fedor V. Fomin , Serge Gaspers , Petr Golovach , Karol Suchan , Stefan Szeider , Erik Jan van Leeuwen , Martin Vatshelle , Yngve Villanger

We study a variant of intersection representations with unit balls, that is, unit disks in the plane and unit intervals on the line. Given a planar graph and a bipartition of the edges of the graph into near and far sets, the goal is to…

Discrete Mathematics · Computer Science 2014-09-01 Md. Jawaherul Alam , Stephen G. Kobourov , Sergey Pupyrev , Jackson Toeniskoetter

Over all graphs (or unicyclic graphs) of a given order, we characterise those graphs that minimise or maximise the number of connected induced subgraphs. For each of these classes, we find that the graphs that minimise the number of…

Combinatorics · Mathematics 2019-09-18 Audace A. V. Dossou-Olory

The interval graph for a set of intervals on a line consists of one vertex for each interval, and an edge for each intersecting pair of intervals. A probe interval graph is a variant that is motivated by an application to genomics, where…

Data Structures and Algorithms · Computer Science 2013-07-23 Ross M. McConnell , Yahav Nussbaum

The recently introduced problem of extending partial interval representations asks, for an interval graph with some intervals pre-drawn by the input, whether the partial representation can be extended to a representation of the entire…

Discrete Mathematics · Computer Science 2014-08-26 Pavel Klavík , Jan Kratochvíl , Yota Otachi , Ignaz Rutter , Toshiki Saitoh , Maria Saumell , Tomáš Vyskočil

This paper considers the problem of defining distributions over graphical structures. We propose an extension of the hyper Markov properties of Dawid and Lauritzen [Ann. Statist. 21 (1993) 1272-1317], which we term structural Markov…

Statistics Theory · Mathematics 2020-04-28 Simon Byrne , A. Philip Dawid

We collect some general results on graph limits associated to hereditary classes of graphs. As examples, we consider some classes defined by forbidden subgraphs and some classes of intersection graphs, including triangle-free graphs,…

Combinatorics · Mathematics 2013-03-29 Svante Janson

In the past decades for more and more graph classes the Graph Isomorphism Problem was shown to be solvable in polynomial time. An interesting family of graph classes arises from intersection graphs of geometric objects. In this work we show…

Data Structures and Algorithms · Computer Science 2016-06-23 Daniel Neuen

Interval graphs are intersection graphs of closed intervals of the real-line. The well-known computational problem, called recognition, asks whether an input graph $G$ can be represented by closed intervals, i.e., whether $G$ is an interval…

Discrete Mathematics · Computer Science 2014-05-20 Pavel Klavík , Jan Kratochvíl , Yota Otachi , Toshiki Saitoh , Tomáš Vyskočil

We obtain the scaling limits of random graphs drawn uniformly in three families of intersection graphs: permutation graphs, circle graphs, and unit interval graphs. The two first families typically generate dense graphs, in these cases we…

Probability · Mathematics 2024-02-12 Frédérique Bassino , Mathilde Bouvel , Valentin Féray , Lucas Gerin , Adeline Pierrot

An r-partite graph is an interval r-graph if corresponding to each vertex we can assign an interval of the real line such that two vertices u and v of different partite sets are adjacent if and only if their corresponding intervals…

Discrete Mathematics · Computer Science 2026-01-30 Indrajit Paul , Ashok Kumar Das

A mixed graph can be seen as a type of digraph containing some edges (two opposite arcs). Here we introduce the concept of sequence mixed graphs, which is a generalization of both sequence graphs and iterated line digraphs. These structures…

Combinatorics · Mathematics 2016-10-13 C. Dalfó , M. A. Fiol , N. López

This paper develops a structural theory of unique shortest paths in real-weighted graphs. Our main goal is to characterize exactly which sets of node sequences, which we call path systems, can be realized as unique shortest paths in a graph…

Data Structures and Algorithms · Computer Science 2018-10-18 Greg Bodwin

Corneil, Olariu, and Stewart [SODA 1998; SIAM Journal on Discrete Mathematics 2009] presented a recognition algorithm for interval graphs by six graph searches. Li and Wu [Discrete Mathematics \& Theoretical Computer Science 2014]…

Data Structures and Algorithms · Computer Science 2020-10-08 Yixin Cao

In a confluence of combinatorics and geometry, simultaneous representations provide a way to realize combinatorial objects that share common structure. A standard case in the study of simultaneous representations is the sunflower case where…

Data Structures and Algorithms · Computer Science 2019-08-26 Ignaz Rutter , Darren Strash , Peter Stumpf , Michael Vollmer

In this paper, we define and characterize signed interval graphs and bigraphs introducing the concept of negative interval. Also we have shown that these classes of graphs are respectively a generalization of well known classes of interval…

Discrete Mathematics · Computer Science 2022-06-14 Ashok Kumar Das , Indrajit Paul

In this paper, we define the quotinet graphs. In particular, we introduce the boundary quotient graphs, admissible boundary quotient graphs and subgraph boundary qoutient graphs. By the property of the quotient spaces, the boundary…

Combinatorics · Mathematics 2007-05-23 Ilwoo Cho

Interval graphs are intersection graphs of closed intervals. A generalization of recognition called partial representation extension was introduced recently. The input gives an interval graph with a partial representation specifying some…

Combinatorics · Mathematics 2016-02-22 Pavel Klavík , Maria Saumell

It has been known since 1991 that the problem of recognizing grid intersection graphs is NP-complete. Here we use a modified argument of the above result to show that even if we restrict to the class of unit grid intersection graphs…

Combinatorics · Mathematics 2013-06-11 Irina Mustaţă , Martin Pergel