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We investigate the asymptotic number of induced subgraphs in power-law uniform random graphs. We show that these induced subgraphs appear typically on vertices with specific degrees, which are found by solving an optimization problem.…

Combinatorics · Mathematics 2022-02-23 Clara Stegehuis

Threshold tolerance graphs and their complement graphs, known as co-TT graphs, were introduced by Monma, Reed, and Trotter[24]. Building on this, Hell et al.[19] introduced the concept of negative interval. Then they proceeded to define…

Discrete Mathematics · Computer Science 2024-11-15 Ashok Kumar Das , Indrajit Paul

Here in particular, we give a characterization of Quasi-line Graphs in terms of forbidden induced subgraphs. In general, we prove a necessary and sufficient condition for a graph to be a union of two cliques.

Combinatorics · Mathematics 2015-10-26 Medha Dhurandhar

Path graphs are intersection graphs of paths in a tree.~In this paper we give a "6\ good characterization" of path graphs, namely, we prove that path graph membership is in $NP\cap CoNP$ without resorting to existing polynomial time…

Discrete Mathematics · Computer Science 2021-09-20 Nicola Apollonio , Lorenzo Balzotti

A rigidity theory is developed for frameworks in a metric space with two types of distance constraints. Mixed sparsity graph characterisations are obtained for the infinitesimal and continuous rigidity of completely regular bar-joint…

Metric Geometry · Mathematics 2019-08-26 Anthony Nixon , Stephen Power

An interval $k$-graph is the intersection graph of a family $\mathcal{I}$ of intervals of the real line partitioned into at most $k$ classes with vertices adjacent if and only if their corresponding intervals intersect and belong to…

Combinatorics · Mathematics 2016-03-01 David E. Brown , Breeann M. Flesch , Larry J. Langley

A matching $M$ in a graph $G$ is said to be uniquely restricted if there is no other matching in $G$ that matches the same set of vertices as $M$. We describe a polynomial-time algorithm to compute a maximum cardinality uniquely restricted…

Discrete Mathematics · Computer Science 2016-05-11 Mathew C. Francis , Dalu Jacob , Satyabrata Jana

An interval graph is proper iff it has a representation in which no interval contains another. Fred Roberts characterized the proper interval graphs as those containing no induced star $K_{1,3}$. Proskurowski and Telle have studied…

Combinatorics · Mathematics 2011-10-03 Jeffrey Beyerl , Robert E. Jamison

This note attempts to understand graph limits as defined by Lovasz and Szegedy (2006)} in terms of harmonic analysis on semigroups. This is done by representing probability distributions of random exchangeable graphs as mixtures of…

Statistics Theory · Mathematics 2020-08-11 Steffen Lauritzen

A matching $M$ in a graph $G$ is uniquely restricted if there is no matching $M'$ in $G$ that is distinct from $M$ but covers the same vertices as $M$. Solving a problem posed by Golumbic, Hirst, and Lewenstein, we characterize the graphs…

Combinatorics · Mathematics 2015-04-10 Lucia Draque Penso , Dieter Rautenbach , Ueverton dos Santos Souza

The present article is an exposition of a theory of discrete convex functions on certain graph structures, developed by the author in recent years. This theory is a spin-off of discrete convex analysis by Murota, and is motivated by…

Optimization and Control · Mathematics 2017-09-08 Hiroshi Hirai

Path graphs are intersection graphs of paths in a tree. We start from the characterization of path graphs by Monma and Wei [C.L.~Monma,~and~V.K.~Wei, Intersection Graphs of Paths in a Tree, J. Combin. Theory Ser. B, 41:2 (1986) 141--181]…

Combinatorics · Mathematics 2022-08-02 Nicola Apollonio , Lorenzo Balzotti

A mixed graph is, informally, an object obtained from a simple undirected graph by choosing an orientation for a subset of its edges. A mixed graph is $(m, n)$-coloured if each edge is assigned one of $m \geq 0$ colours, and each arc is…

Combinatorics · Mathematics 2025-01-15 Gary MacGillivray , Shahla Nasserasr , Feiran Yang

Motivated by circle graphs, and the enumeration of Euler circuits, we define a one-variable ``interlace polynomial'' for any graph. The polynomial satisfies a beautiful and unexpected reduction relation, quite different from the cut and…

Combinatorics · Mathematics 2007-05-23 Richard Arratia , Bela Bollobas , Gregory B. Sorkin

In this monography, it is proposed to consider the concepts of spectra of edge cuts and edge cycles of a graph as a basic mathematical structure for solving the problem of graph isomorphism. An edge cut is defined by an edge and the…

Combinatorics · Mathematics 2024-06-13 Sergey Kurapov , Maxim Davidovsky

We prove several criteria for quasi-isometry between non-locally-finite graphs and their structure trees. Results of M\"oller in \cite{moeller92ends2} for locally finite and transitive graphs are generalized. We also give a criterion which…

Combinatorics · Mathematics 2007-05-23 Bernhard Krön

In this paper we present a characterisation, by an infinite family of minimal forbidden induced subgraphs, of proper circular arc graphs which are intersection graphs of paths on a grid, where each path has at most one bend (turn).

Computational Geometry · Computer Science 2018-08-29 Esther Galby , Maria Pia Mazzoleni , Bernard Ries

Metric graphs are often introduced based on combinatorics, upon "associating" each edge of a graph with an interval; or else, casually "gluing" a collection of intervals at their endpoints in a network-like fashion. Here we propose an…

Combinatorics · Mathematics 2021-03-17 Delio Mugnolo

The most elusive problem around the class of circular-arc graphs is identifying all minimal graphs that are not in this class. The main obstacle is the lack of a systematic way of enumerating these minimal graphs. McConnell [FOCS 2001]…

Combinatorics · Mathematics 2025-03-18 Yixin Cao , Jan Derbisz , Tomasz Krawczyk

A key feature of neural network architectures is their ability to support the simultaneous interaction among large numbers of units in the learning and processing of representations. However, how the richness of such interactions trades off…

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