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In the present paper, we introduce the concept of universal graph series. We then present four invariants of graphs and discuss some of their properties. In particular, one of these invariants is a generalization of the chromatic symmetric…

Combinatorics · Mathematics 2025-01-22 Tsuyoshi Miezaki , Akihiro Munemasa , Yusaku Nishimura , Tadashi Sakuma , Shuhei Tsujie

In this paper, we introduce a new method to compute magnitude homology of general graphs. To each direct sum component of magnitude chain complexes, we assign a pair of simplicial complexes whose simplicial chain complex is isomorphic to…

Algebraic Topology · Mathematics 2020-03-19 Yasuhiko Asao , Kengo Izumihara

In [Steve Butler. A note about cospectral graphs for the adjacency and normalized Laplacian matrices. Linear Multilinear Algebra, 58(3-4):387-390, 2010.], Butler constructed a family of bipartite graphs, which are cospectral for both the…

Combinatorics · Mathematics 2020-02-04 M. Rajesh Kannan , Shivaramakrishna Pragada

For every positive integer $n$, we find a complete classification for planar graphs according to the collection of numbers of common neighbours for every $n$-tuple of distinct vertices. Our results expand the literature on planar graphical…

Combinatorics · Mathematics 2025-11-25 Riccardo W. Maffucci

We investigate connections between the symmetries (automorphisms) of a graph and its spectral properties. Whenever a graph has a symmetry, i.e. a nontrivial automorphism $\phi$, it is possible to use $\phi$ to decompose any matrix…

Combinatorics · Mathematics 2016-10-07 Wayne Barrett , Amanda Francis , Ben Webb

In this review we establish various connections between complex networks and symmetry. While special types of symmetries (e.g., automorphisms) are studied in detail within discrete mathematics for particular classes of deterministic graphs,…

General Finance · Quantitative Finance 2010-11-04 Diego Garlaschelli , Franco Ruzzenenti , Riccardo Basosi

Graph invariants provide a powerful analytical tool for investigation of abstract structures of graphs. They, combined in convenient relations, carry global and general information about a graph and its various substructures such as cycle…

Combinatorics · Mathematics 2010-09-15 Zh. G. Nikoghosyan

We consider orbit partitions of groups of automorphisms for the symplectic graph and apply Godsil-McKay switching. As a result, we find four families of strongly regular graphs with the same parameters as the symplectic graphs, including…

Combinatorics · Mathematics 2016-06-13 Sho Kubota

This paper presents a concise tutorial on spectral clustering for broad spectrum graphs which include unipartite (undirected) graph, bipartite graph, and directed graph. We show how to transform bipartite graph and directed graph into…

Machine Learning · Computer Science 2010-07-13 Andri Mirzal , Masashi Furukawa

We characterise the form of all simple, finite graphs for which the girth of the graph is equal to the circumference of the graph. We apply this to prove a bound on the number of edges in such a graph.

Combinatorics · Mathematics 2022-10-11 Lewis Stanton , Jeffrey Thompson

Graph-level representations are crucial tools for characterising structural differences between graphs. However, comparing graphs with different cardinalities, even when sampled from the same underlying distribution, remains challenging.…

Machine Learning · Computer Science 2026-05-08 Katharina Limbeck , Nadja Häusermann , Martin Carrasco , Guy Wolf , Bastian Rieck

We introduce a new notation for representing labeled regular bipartite graphs of arbitrary degree. Several enumeration problems for labeled and unlabeled regular bipartite graphs have been introduced. A general algorithm for enumerating all…

Discrete Mathematics · Computer Science 2015-12-31 Vivek S. Nittoor

Computing the embedding distribution of a given graph is a fundamental question in topological graph theory. In this article, we extend our viewpoint to a sequence of graphs and consider their asymptotic embedding distributions, which are…

Combinatorics · Mathematics 2025-07-22 Yichao Chen , Wenjie Fang , Zhicheng Gao , Jinlian Zhang

Let $n$ be any positive integer and let $F_n$ be the friendship (or Dutch windmill) graph with $2n+1$ vertices and $3n$ edges. Here we study graphs with the same adjacency spectrum as the $F_n$. Two graphs are called cospectral if the…

Combinatorics · Mathematics 2013-07-23 Alireza Abdollahi , Shahrooz Janbaz , Mohammad Reza Oboudi

We investigate whether it is typical for a sparse graph to be uniquely characterized by its adjacency spectrum up to isomorphism. Our first result shows that the giant component of an Erd\H{o}s-R\'enyi graph is cospectral when the average…

Combinatorics · Mathematics 2026-02-27 Nils Van de Berg , Alexander Van Werde

Construction of non-isomorphic cospectral graphs is a nontrivial problem in spectral graph theory specially for large graphs. In this paper, we establish that graph theoretical partial transpose of a graph is a potential tool to create…

Combinatorics · Mathematics 2018-08-13 Supriyo Dutta , Bibhas Adhikari

We propose a new approach for defining and searching clusters in graphs that represent real technological or transaction networks. In contrast to the standard way of finding dense parts of a graph, we concentrate on the structure of edges…

Combinatorics · Mathematics 2021-03-16 András London , Ryan R. Martin , András Pluhár

We construct infinite families of graphs that are determined by their generalized spectrum. This construction is based on new formulae for the determinant of the walk matrix of a graph. The graphs constructed here all satisfy a lower…

Combinatorics · Mathematics 2018-09-05 Fenjin Liu , Johannes Siemons , Wei Wang

We investigate the relationship between the structure of a discrete graphical model and the support of the inverse of a generalized covariance matrix. We show that for certain graph structures, the support of the inverse covariance matrix…

Machine Learning · Statistics 2014-01-07 Po-Ling Loh , Martin J. Wainwright

Mutual visibility in graphs provides a framework for analysing how vertices can observe one another along shortest paths free of internal obstructions. The visibility polynomial, which enumerates mutual-visibility sets of all orders, has…

Combinatorics · Mathematics 2026-04-10 Tonny K B , Shikhi M