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We study random graphs with arbitrary distributions of expected degree and derive expressions for the spectra of their adjacency and modularity matrices. We give a complete prescription for calculating the spectra that is exact in the limit…

Social and Information Networks · Computer Science 2013-02-04 Raj Rao Nadakuditi , M. E. J. Newman

Graph-based methods have been quite successful in solving unsupervised and semi-supervised learning problems, as they provide a means to capture the underlying geometry of the dataset. It is often desirable for the constructed graph to…

Machine Learning · Computer Science 2019-04-16 Aamir Anis , Aly El Gamal , Salman Avestimehr , Antonio Ortega

For a graph $G$ and a non-zero real number $\alpha$, the graph invariant $S_{\alpha}(G)$ is the sum of the $\alpha^{th}$ power of the non-zero signless Laplacian eigenvalues of $G$. In this paper, we obtain the sharp bounds of…

Combinatorics · Mathematics 2013-06-07 Lihua You , Jieshan Yang

According to a recent conjecture, isospectral objects have different nodal count sequences. We study generalized Laplacians on discrete graphs, and use them to construct the first non-trivial counter-examples to this conjecture. In…

Mathematical Physics · Physics 2016-11-25 Idan Oren , Ram Band

We show that for threshold graphs, the eigenvalues of the signless Laplacian matrix interlace with the degrees of the vertices. As an application, we show that the signless Brouwer conjecture holds for threshold graphs, i.e., for threshold…

Combinatorics · Mathematics 2023-08-25 Christoph Helmberg , Guilherme Porto , Guilherme Torres , Vilmar Trevisan

Nonlinear spectral graph theory is an extension of the traditional (linear) spectral graph theory and studies relationships between spectral properties of nonlinear operators defined on a graph and topological properties of the graph…

Spectral Theory · Mathematics 2025-04-07 Piero Deidda , Francesco Tudisco , Dong Zhang

In this paper, we give a linear algorithm for obtaining the Laplacian eigenvalues of a cograph. This approach is more efficient as there is no need to directly compute the eigenvalues of Laplacian matrix related to this class of graph. As…

Combinatorics · Mathematics 2024-09-16 Guantao Chen , Fernando C. Tura

In a paper by Nishikawa and Motter, a quantity called the normalized spread of the Laplacian eigenvalues is used to measure the synchronizability of certain network dynamics. Through simulations, and without theoretical validation, it is…

Optimization and Control · Mathematics 2026-01-09 Susie Lu , John Urschel , Ji Liu

We offer a new method for proving that the maximal eigenvalue of the normalized graph Laplacian of a graph with $n$ vertices is at least $\frac{n+1}{n-1}$ provided the graph is not complete and that equality is attained if and only if the…

Spectral Theory · Mathematics 2021-04-07 Jürgen Jost , Raffaella Mulas , Florentin Münch

We conjecture that the sum of the square roots of the Laplacian eigenvalues of a graph does not exceed the sum of the square roots of its signless Laplacian eigenvalues.

Combinatorics · Mathematics 2009-09-07 S. Akbari , E. Ghorbani , M. R. Oboudi

We describe the spectrum of a non-self-adjoint elliptic system on a finite interval. Under certain conditions we find that the eigenvalues form a discrete set and converge asymptotically at infinity to one of several straight lines. The…

Spectral Theory · Mathematics 2007-05-23 E. B. Davies

In this paper, we compute the Laplacian spectrum of non-commuting graphs of some classes of finite non-abelian groups. Our computations reveal that the non-commuting graphs of all the groups considered in this paper are L-integral. We also…

Group Theory · Mathematics 2017-05-04 Parama Dutta , Jutirekha Dutta , Rajat Kanti Nath

We propose a Laplacian based on general inner product spaces, which we call the inner product Laplacian. We show the combinatorial and normalized graph Laplacians, as well as other Laplacians for hypergraphs and directed graphs, are special…

Combinatorics · Mathematics 2025-04-16 Sinan G. Aksoy , Stephen J. Young

Spectral graph theory is a captivating area of graph theory that employs the eigenvalues and eigenvectors of matrices associated with graphs to study them. In this paper, we present a collection of $20$ topics in spectral graph theory,…

Combinatorics · Mathematics 2025-10-16 Lele Liu , Bo Ning

We consider the problem of offline, pool-based active semi-supervised learning on graphs. This problem is important when the labeled data is scarce and expensive whereas unlabeled data is easily available. The data points are represented by…

Machine Learning · Computer Science 2014-05-20 Akshay Gadde , Aamir Anis , Antonio Ortega

On a finite connected metric graph, we establish upper bounds for the eigenvalues of the Laplacian. These bounds depend on the length, the Betti number, and the number of pendant vertices. For trees, these estimates are sharp. We also…

Spectral Theory · Mathematics 2016-09-26 Sinan Ariturk

Let G be a simple undirected connected graph. In this paper, new upper bounds on the distance Laplacian spectral radius of G are obtained. Moreover, new lower and upper bounds for the distance signless Laplacian spectral radius of G are…

Combinatorics · Mathematics 2019-06-14 Roberto C. Díaz , Ana I. Julio , Oscar Rojo

Graphs with few distinct eigenvalues have been investigated extensively. In this paper, we focus on another relevant topic: characterizing graphs with some eigenvalue of large multiplicity. Specifically, the normalized Laplacian matrix of a…

Combinatorics · Mathematics 2020-01-01 Fenglei Tian , Dein Wong

Large graphs commonly appear in social networks, knowledge graphs, recommender systems, life sciences, and decision making problems. Summarizing large graphs by their high level properties is helpful in solving problems in these settings.…

Machine Learning · Statistics 2022-08-01 Elise van der Pol , Ian Gemp , Yoram Bachrach , Richard Everett

We give an upper bound on the maximal eigenvalue of the adjacency matrix of a connected graph in terms of its maximum degree, diameter and order. This bound is best possible up to a constant factor and improves prevoius results of…

Combinatorics · Mathematics 2007-05-23 Vladimir Nikiforov