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We define a natural class of graphs by generalizing prior notions of visibility, allowing the representing regions and sightlines to be arbitrary. We consider mainly the case of compact connected representing regions, proving two results…

Combinatorics · Mathematics 2007-05-23 Mike Develin , Stephen Hartke , David Petrie Moulton

We extend the concept of the law of a finite graph to graphings, which are, in general, infinite graphs whose vertices are equipped with the structure of a probability space. By doing this, we obtain a vast array of new unimodular measures.…

Combinatorics · Mathematics 2012-03-13 Igor Artemenko

A new complete invariant for acyclic graphs is presented

Computational Complexity · Computer Science 2010-08-10 A. Prolubnikov

Fractional (hyper-)graph theory is concerned with the specific problems that arise when fractional analogues of otherwise integer-valued (hyper-)graph invariants are considered. The focus of this paper is on fractional edge covers of…

Discrete Mathematics · Computer Science 2023-09-25 Georg Gottlob , Matthias Lanzinger , Reinhard Pichler , Igor Razgon

Building on existing algorithms and results, we offer new insights and algorithms for various problems related to detecting maximal and maximum bicliques. Most of these results focus on graphs with small maximum degree, providing improved…

Data Structures and Algorithms · Computer Science 2024-12-17 George Manoussakis

The boxicity of a graph $G$ is the minimum non-negative integer $k$ such that $G$ can be isomorphic to the intersection graph of a family of boxes in Euclidean $k$-space, where a box in Euclidean $k$-space is the Cartesian product of $k$…

Combinatorics · Mathematics 2020-04-16 Akira Kamibeppu

Computer or communication networks are so designed that they do not easily get disrupted under external attack and, moreover, these are easily reconstructible if they do get disrupted. These desirable properties of networks can be measured…

Combinatorics · Mathematics 2011-09-23 T. C. E. Cheng , Yinkui Li , Chuandong Xu , Shenggui Zhang

A Berge cycle of length $\ell$ in a hypergraph is an alternating sequence of $\ell$ distinct vertices and $\ell$ distinct edges $v_1,e_1,v_2, \ldots, v_\ell, e_{\ell}$ such that $\{v_i, v_{i+1}\} \subseteq e_i$ for all $i$, with indices…

Combinatorics · Mathematics 2024-10-30 Teegan Bailey , Yupei Li , Ruth Luo

Let $ \Phi=(G, \varphi) $ be a connected complex unit gain graph ($ \mathbb{T} $-gain graph) on a simple graph $ G $ with $ n $ vertices and maximum vertex degree $ \Delta $. The associated adjacency matrix and degree matrix are denoted by…

Combinatorics · Mathematics 2021-01-12 Aniruddha Samanta , M. Rajesh Kannan

A vertex colouring of a graph is called asymmetric if the only automorphism which preserves it is the identity. Tucker conjectured that if every automorphism of a connected, locally finite graph moves infinitely many vertices, then there is…

Combinatorics · Mathematics 2020-07-21 Florian Lehner , Monika Pilśniak , Marcin Stawiski

We demonstrate that graph-based models are fully capable of representing higher-order interactions, and have a long history of being used for precisely this purpose. This stands in contrast to a common claim in the recent literature on…

Physics and Society · Physics 2026-02-20 Tiago P. Peixoto , Leto Peel , Thilo Gross , Manlio De Domenico

A biased graph is a graph $G$, together with a distinguished subset $\mathcal{B}$ of its cycles so that no Theta-subgraph of $G$ contains precisely two cycles in $\mathcal{B}$. A large number of biased graphs can be constructed by choosing…

Combinatorics · Mathematics 2020-12-14 Peter Nelson , Jorn van der Pol

A connected $k$-uniform hypergraph with $n$ vertices and $m$ edges is called $r$-cyclic if $n=m(k-1)-r+1$. For $r=1$ or $2$, the hypergraph is simply called unicyclic or bicyclic. In this paper we investigate hypergraphs that attain larger…

Combinatorics · Mathematics 2016-07-29 Chen Ouyang , Liqun Qi , Xiying Yuan

In this paper, a new concept in graphs namely well-f-coveredness is introduced. We characterize all graphs with such property, whose maximum induced forests are of boundary order. Also we prove several propositions concerning with obtaining…

Combinatorics · Mathematics 2021-06-01 Reza Jafarpour-Golzari

We introduce the notion of recurrence and transience for graphs over non-Archimedean ordered field. To do so we relate these graphs to random walks of directed graphs over the reals. In particular, we give a characterization of the real…

Combinatorics · Mathematics 2024-06-26 Matthias Keller , Anna Muranova

A graph $H$ is said to be positive if the homomorphism density $t_H(G)$ is non-negative for all weighted graphs $G$. The positive graph conjecture proposes a characterisation of such graphs, saying that a graph is positive if and only if it…

Combinatorics · Mathematics 2024-04-29 David Conlon , Joonkyung Lee , Leo Versteegen

We study various acyclicity conditions on higher-categorical pasting diagrams in the combinatorial framework of regular directed complexes. We present an apparently weakest acyclicity condition under which the $\omega$-category presented by…

Category Theory · Mathematics 2024-09-02 Amar Hadzihasanovic , Diana Kessler

There has been a great deal of research on graphs defined on algebraic structures in the last two decades. In this paper we begin an exploration of hypergraphs defined on algebraic structures, especially groups, to investigate whether this…

Combinatorics · Mathematics 2023-03-02 Peter J. Cameron , Aparna Lakshmanan S. , Midhuna V. Ajith

Here we have investigated a few properties of the eigenvalues of normalized (geometric) graph Laplacian in different graphs. Preservation of eigenvalue 1 from a particular subgraph to the entire graph, the spectrum of the graph constructed…

Combinatorics · Mathematics 2014-03-07 Anirban Banerjee

In this paper, we relate the seemingly unrelated concepts of treewidth and boxicity. Our main result is that, for any graph G, boxicity(G) <= treewidth(G) + 2. We also show that this upper bound is (almost) tight. Our result leads to…

Combinatorics · Mathematics 2007-05-23 L. Sunil Chandran , Naveen Sivadasan
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