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In recent work, the authors developed a simple method of constructing topological spaces from certain well-behaved partially ordered sets -- those coming from sequences of relations between finite sets. This method associates a given poset…

General Topology · Mathematics 2025-09-11 Adam Bartoš , Tristan Bice , Alessandro Vignati

Graphs are widely used as a popular representation of the network structure of connected data. Graph data can be found in a broad spectrum of application domains such as social systems, ecosystems, biological networks, knowledge graphs, and…

Machine Learning · Computer Science 2021-05-04 Feng Xia , Ke Sun , Shuo Yu , Abdul Aziz , Liangtian Wan , Shirui Pan , Huan Liu

We give a construction of strongly regular Cayley graphs on finite fields $\F_q$ by using union of cyclotomic classes and index 4 Gauss sums. In particular, we obtain two infinite families of strongly regular graphs with new parameters.

Combinatorics · Mathematics 2012-04-03 Gennian Ge , Qing Xiang , Tao Yuan

In this paper, we aim to address the open questions raised in various recent papers regarding characterization of circulant graphs with three or four distinct eigenvalues in their spectra. Our focus is on providing characterizations and…

Combinatorics · Mathematics 2023-10-11 Milan Bašić

An edge subset $S$ of a connected graph $G$ is called an anti-Kekul\'{e} set if $G-S$ is connected and has no perfect matching. We can see that a connected graph $G$ has no anti-Kekul\'{e} set if and only if each spanning tree of $G$ has a…

Combinatorics · Mathematics 2016-02-02 Baoyindureng Wu , Heping Zhang

This article provides structural characterization of simple graphs whose edge-set can be partitioned into maximum matchings. We use Vizing's classification of simple graphs based on edge chromatic index.

Combinatorics · Mathematics 2012-10-19 Niraj Khare

Petersen's seminal work in 1891 asserts that the edge-set of a cubic graph can be covered by distinct perfect matchings if and only if it is bridgeless. Actually, it is known that for a very large fraction of bridgeless cubic graphs, every…

Combinatorics · Mathematics 2024-10-16 Jan Goedgebeur , Davide Mattiolo , Giuseppe Mazzuoccolo , Jarne Renders , Isaak H. Wolf

This article introduces a new approach to discrete curvature based on the concept of effective resistances. We propose a curvature on the nodes and links of a graph and present the evidence for their interpretation as a curvature. Notably,…

Differential Geometry · Mathematics 2022-09-26 Karel Devriendt , Renaud Lambiotte

A signed bipartite (simple) graph $(G, \sigma)$ is said to be $C_{-4}$-critical if it admits no homomorphism to $C_{-4}$ (a negative 4-cycle) but every proper subgraph of it does. In this work, first of all we show that the notion of…

Combinatorics · Mathematics 2021-11-23 Reza Naserasr , Lan Anh Pham , Zhouningxin Wang

A unit disk graph is the intersection graph of disks of equal radii in the plane. The class of unit disk graphs is hereditary, and therefore admits a characterization in terms of minimal forbidden induced subgraphs. In spite of quite active…

Combinatorics · Mathematics 2016-02-29 Aistis Atminas , Viktor Zamaraev

We obtain a bound on the girth g of a quaternion unit gain graph in terms of the rank r of its adjacency matrix. In particular, we show that g <= r + 2 and characterize all quaternion unit gain graphs for which g = r+2. This extends…

Combinatorics · Mathematics 2024-12-02 Suliman Khan , Edwin R. van Dam

We characterise the quintic (i.e. 5-regular) multigraphs with the property that every edge lies in a triangle. Such a graph is either from a set of small graphs or is formed by adding a perfect matching to a line graph of a cubic graph as…

Combinatorics · Mathematics 2021-07-09 James Preen

A graph {\it has cutwidth at most 2} if one can number its vertices by $1,\ldots n$ so that for every $i=1,\ldots,n-1$ there are at most 2 edges $(u,v)$ such that $u\le i<v$. A characterization of graphs having cutwidth at most 2 in terms…

Combinatorics · Mathematics 2019-12-13 Nadya Khoroshavkina

This work introduces a novel algorithm for finding the connected components of a graph where the vertices and edges are grouped into sets defining a Set--Based Graph. The algorithm, under certain restrictions on those sets, has the…

Data Structures and Algorithms · Computer Science 2020-11-30 Ernesto Kofman , Denise Marzorati , Joaquín Fernández

On the basis of recent results on hamiltonicity and hamiltonian connectedness in the square of a 2-block, we determine the most general block-cutvertex structure a graph $G$ may have in order to guarantee that $G^2$ is hamiltonian,…

Combinatorics · Mathematics 2023-09-28 J. Ekstein , H. Fleischner

In this paper, we classify all the finite groups $G$ such that the commuting graph $\Gamma_C(G)$, order-sum graph $\Gamma_{OS}(G)$ and non-inverse graph $\Gamma_{NI}(G)$ are minimally edge connected graphs. We also classify all the finite…

Combinatorics · Mathematics 2024-12-02 Siddharth Malviy , Vipul Kakkar

Graph connectivity serves as a fundamental metric for evaluating the reliability and fault tolerance of interconnection networks. To more precisely characterize network robustness, the concept of cyclic connectivity has been introduced,…

Combinatorics · Mathematics 2025-11-04 Ting Tian , Shumin Zhang , Bo Zhu

We present results from numerical studies of supervised learning operations in recurrent networks considered as graphs, leading from a given set of input conditions to predetermined outputs. Graphs that have optimized their output for…

Adaptation and Self-Organizing Systems · Physics 2007-05-23 H. Atmanspacher , T. Filk

We present the first linear-time algorithm that computes the $4$-edge-connected components of an undirected graph. Hence, we also obtain the first linear-time algorithm for testing $4$-edge connectivity. Our results are based on a…

Data Structures and Algorithms · Computer Science 2021-05-10 Loukas Georgiadis , Giuseppe F. Italiano , Evangelos Kosinas

Let $G$ be a connected undirected graph on $n$ vertices with no loops but possibly multiedges. Given an arithmetical structure $(\textbf{r}, \textbf{d})$ on $G$, we describe a construction which associates to it a graph $G'$ on $n-1$…

Combinatorics · Mathematics 2021-06-10 Christopher Keyes , Tomer Reiter