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For vertex and edge connectivity we construct infinitely many pairs of regular graphs with the same spectrum, but with different connectivity.

Combinatorics · Mathematics 2019-09-12 Willem H. Haemers

We prove spectral localization for infinite metric graphs with a self-adjoint Laplace operator and a random potential. To do so we adapt the multiscale analysis (MSA) from the R^d-case to metric graphs. In the MSA a covering of the graph is…

Spectral Theory · Mathematics 2012-08-31 Carsten Schubert

Measuring the topological overlap of two graphs becomes important when assessing the changes between temporally adjacent graphs in a time-evolving network. Current methods depend on the fraction of nodes that have persisting edges. This…

Physics and Society · Physics 2014-03-06 Fiona Pigott , Mauricio Rene Herrera Marin

A graph is trivial if it contains one vertex and no edges. The essential connectivity $\kappa^{\prime}$ of $G$ is defined to be the minimum number of vertices of $G$ whose removal produces a disconnected graph with at least two non-trivial…

Combinatorics · Mathematics 2024-06-26 Wenxiu Ding , Dan Li , Yu Wang , Jixiang Meng

Spectral graph convolutional networks are generalizations of standard convolutional networks for graph-structured data using the Laplacian operator. A common misconception is the instability of spectral filters, i.e. the impossibility to…

Machine Learning · Computer Science 2020-12-21 Axel Nilsson , Xavier Bresson

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

We introduce a new notion of graph sparsificaiton based on spectral similarity of graph Laplacians: spectral sparsification requires that the Laplacian quadratic form of the sparsifier approximate that of the original. This is equivalent to…

Data Structures and Algorithms · Computer Science 2010-07-22 Daniel A. Spielman , Shang-Hua Teng

We derive exact equations that determine the spectra of undirected and directed sparsely connected regular graphs containing loops of arbitrary length. The implications of our results to the structural and dynamical properties of networks…

Statistical Mechanics · Physics 2011-12-07 F. L. Metz , I. Neri , D. Bollé

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

The spectrum of a graph is closely related to many graph parameters. In particular, the spectral gap of a regular graph which is the difference between its valency and second eigenvalue, is widely seen an algebraic measure of connectivity…

Combinatorics · Mathematics 2022-04-06 Sebastian M. Cioabă , Jack H. Koolen , Masato Mimura , Hiroshi Nozaki , Takayuki Okuda

We establish convergence of spectra of Neumann Laplacian in a thin neighborhood of a branching 2D structure in 3D to the spectrum of an appropriately defined operator on the structure itself. This operator is a 2D analog of the well known…

Mathematical Physics · Physics 2019-08-20 James E. Corbin , Peter Kuchment

The spectral dimension is an indicator of geometry and topology of spacetime and a tool to compare the description of quantum geometry in various approaches to quantum gravity. This is possible because it can be defined not only on smooth…

High Energy Physics - Theory · Physics 2014-06-19 Gianluca Calcagni , Daniele Oriti , Johannes Thürigen

We examine the band-gap structure of the spectrum of the Neumann problem for the Laplace operator in a strip with periodic dense transversal perforation by identical holes of a small diameter $\varepsilon>0$. The periodicity cell itself…

Analysis of PDEs · Mathematics 2023-02-14 Delfina Gómez , Sergei A. Nazarov , Rafael Orive-Illera , Maria-Eugenia Pérez-Martínez

The term interlacing refers to systematic inequalities between the sequences of eigenvalues of two operators defined on objects related by a specific oper- ation. In particular, knowledge of the spectrum of one of the objects then implies…

Spectral Theory · Mathematics 2011-12-12 Danijela Horak , Jürgen Jost

We present a number of relations involving the number of cliques in a graph and its spectral radius.

Combinatorics · Mathematics 2007-05-23 Bela Bollobas , Vladimir Nikiforov

For the almost Mathieu operator with a small coupling constant, for a series of spectral gaps, we describe the asymptotic locations of the gaps and get lower bounds for their lengths. The results are obtained by analysing a monodromy…

Spectral Theory · Mathematics 2021-02-22 Alexander Fedotov

We compute spectra of symmetric random matrices defined on graphs exhibiting a modular structure. Modules are initially introduced as fully connected sub-units of a graph. By contrast, inter-module connectivity is taken to be incomplete.…

Disordered Systems and Neural Networks · Physics 2009-08-24 G. Ergun , R. Kuehn

For a connected graph, the distance spectral radius is the largest eigenvalue of its distance matrix, and the distance energy is defined as the sum of the absolute values of the eigenvalues of its distance matrix. We establish lower and…

Combinatorics · Mathematics 2011-01-25 Bo Zhou , Aleksandar Ilic

We consider discrete Schr\"odinger operators with periodic potentials on periodic graphs. Their spectra consist of a finite number of bands. We perturb a periodic graph by adding edges in a periodic way (without changing the vertex set) and…

Spectral Theory · Mathematics 2024-07-02 Natalia Saburova

Aldous and Fill conjectured that the maximum relaxation time for the random walk on a connected regular graph with $n$ vertices is $(1+o(1)) \frac{3n^2}{2\pi^2}$. This conjecture can be rephrased in terms of the spectral gap as follows: the…

Combinatorics · Mathematics 2022-07-22 Maryam Abdi , Ebrahim Ghorbani