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In this work, we present a theoretical study of signals with sparse representations in the vertex domain of a graph, which is primarily motivated by the discrepancy arising from respectively adopting a synthesis and analysis view of the…

Signal Processing · Electrical Eng. & Systems 2018-11-16 Madeleine S. Kotzagiannidis , Mike E. Davies

The Laplacian spread of a graph is the difference between the largest eigenvalue and the second-smallest eigenvalue of the Laplacian matrix of the graph. We find that the class of strongly regular graphs attains the maximum of largest…

Combinatorics · Mathematics 2014-11-25 Fan-Hsuan Lin , Chih-wen Weng

We consider the problem of characterizing the `duality gap' between sparse synthesis- and cosparse analysis-driven signal models through the lens of spectral graph theory, in an effort to comprehend their precise equivalencies and…

Discrete Mathematics · Computer Science 2022-04-06 Madeleine S. Kotzagiannidis , Mike E. Davies

There is a profound connection between copositive matrices and graph theory. Copositive matrices provide a powerful tool for formulating and solving various challenging graph-related problems. Conversely, graph theory provides a rich set of…

Optimization and Control · Mathematics 2024-10-11 O. I. Kostyukova , T. V. Tchemisova

A graph is near-planar if it can be obtained from a planar graph by adding an edge. We show the surprising fact that it is NP-hard to compute the crossing number of near-planar graphs. A graph is 1-planar if it has a drawing where every…

Computational Geometry · Computer Science 2012-03-28 Sergio Cabello , Bojan Mohar

We examine the capacity of the complementarity spectrum to distinguish non-isomorphic digraphs. We focus on the seven families with exactly three complementarity eigenvalues. Our findings reveal that in some, but not all families, any two…

Combinatorics · Mathematics 2024-03-19 Diego Bravo , Florencia Cubría , Marcelo Fiori , Gustavo Rama

Generative models for graphs have been typically committed to strong prior assumptions concerning the form of the modeled distributions. Moreover, the vast majority of currently available models are either only suitable for characterizing…

Social and Information Networks · Computer Science 2012-10-19 Antonino Freno , Mikaela Keller , Gemma C. Garriga , Marc Tommasi

For random graphs distributed according to a stochastic block model, we consider the inferential task of partioning vertices into blocks using spectral techniques. Spectral partioning using the normalized Laplacian and the adjacency matrix…

A metrized graph is a compact singular 1-manifold endowed with a metric. A given metrized graph can be modelled by a family of weighted combinatorial graphs. If one chooses a sequence of models from this family such that the vertices become…

Classical Analysis and ODEs · Mathematics 2007-05-23 X. W. C. Faber

The main goal of the paper is to characterize new classes of multicone graphs which are determined by both adjacency and Laplacian spectra. A multicone graph is defined to be the join of a clique and a regular graph. A wheel graph obtained…

Combinatorics · Mathematics 2018-03-02 Ali Zeydi Abdian

The eigenvalues of the normalized Laplacian of a graph provide information on its topological and structural characteristics and also on some relevant dynamical aspects, specifically in relation to random walks. In this paper we determine…

Spectral Theory · Mathematics 2016-04-05 Pinchen Xie , Zhongzhi Zhang , Francesc Comellas

The graphs with all equal negative or positive eigenvalues are special kind in the spectral graph theory. In this article, several iterated line graphs $\mathcal{L}^k(G)$ with all equal negative eigenvalues $-2$ are characterized for $k\ge…

Combinatorics · Mathematics 2025-11-25 Harishchandra S. Ramane , B. Parvathalu , Daneshwari Patil , K. Ashoka

Graph neural networks process information on graphs represented at a given resolution scale. We analyze the effect of using different coarse-grained graph resolutions, obtained through the Laplacian renormalization group theory, on node…

Machine Learning · Computer Science 2025-04-15 Francesco Caso , Giovanni Trappolini , Andrea Bacciu , Pietro Liò , Fabrizio Silvestri

We provide a criterion to distinguish two graphs which are indistinguishable by $2$-dimensional Weisfeiler-Lehman algorithm for almost all graphs. Haemers conjectured that almost all graphs are identified by their spectrum. Our approach…

Combinatorics · Mathematics 2025-11-21 Wei Wang , Da Zhao

Graph learning methods have recently been receiving increasing interest as means to infer structure in datasets. Most of the recent approaches focus on different relationships between a graph and data sample distributions, mostly in…

Machine Learning · Computer Science 2020-03-23 Hermina Petric Maretic , Pascal Frossard

We show that the degree distributions of graphs do not suffice to characterize the synchronization of systems evolving on them. We prove that, for any given degree sequence satisfying certain conditions, there exists a connected graph…

Adaptation and Self-Organizing Systems · Physics 2007-08-30 Fatihcan M. Atay , Tuerker Biyikoglu , Juergen Jost

Graph signal processing analyzes signals supported on the nodes of a graph by defining the shift operator in terms of a matrix, such as the graph adjacency matrix or Laplacian matrix, related to the structure of the graph. With respect to…

Signal Processing · Electrical Eng. & Systems 2018-03-01 Stephen Kruzick , José M. F. Moura

Graphs arising in statistical problems, signal processing, large networks, combinatorial optimization, and data analysis are often dense, which causes both computational and storage bottlenecks. One way of \textit{sparsifying} a…

Numerical Analysis · Mathematics 2023-04-27 Neophytos Charalambides , Alfred O. Hero

We prove that for a pair of cospectral graphs G and H, there exist their non trivial lifts G0 and H0 which are cospectral. More over for a pair of cospectral graphs on 6 vertices, we find some cospectral lifts of them.

Combinatorics · Mathematics 2016-01-12 F. Ramezani

Bipartite graphs are a fundamental concept in graph theory with diverse applications. A graph is bipartite iff it contains no odd cycles, a characteristic that has many implications in diverse fields ranging from matching problems to the…

Combinatorics · Mathematics 2024-12-10 Marzieh Eidi , Sayan Mukherjee