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Graph signal processing (GSP) is a prominent framework for analyzing signals on non-Euclidean domains. The graph Fourier transform (GFT) uses the combinatorial graph Laplacian matrix to reveal the spectral decomposition of signals in the…

Machine Learning · Computer Science 2024-06-13 Changhao Shi , Gal Mishne

For a graph $G$, the signless Laplacian Estrada index is defined as $SLEE(G)=\sum^{n}_{i=1}e^{q^{}_i}$,where $q_1, q_2, \dots, q_n$are the eigenvalues of the signless Laplacian matrix of $G$. In this paper, we first characterize the…

Combinatorics · Mathematics 2017-08-08 Hamid Reza Ellahi , Ramin Nasiri , Gholam Hossein Fath-Tabar , Ahmad Gholami

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

We give a combinatorial characterization of graphs whose normalized Laplacian has three distinct eigenvalues. Strongly regular graphs and complete bipartite graphs are examples of such graphs, but we also construct more exotic families of…

Combinatorics · Mathematics 2012-02-15 Edwin R. van Dam , Gholamreza Omidi

Many interesting graph families contain only 2-connected graphs, which have ear decompositions. We develop a technique to generate families of unlabeled 2-connected graphs using ear augmentations and apply this technique to two problems. In…

Combinatorics · Mathematics 2011-04-29 Derrick Stolee

This paper proposes a scalable algorithmic framework for spectral reduction of large undirected graphs. The proposed method allows computing much smaller graphs while preserving the key spectral (structural) properties of the original…

Data Structures and Algorithms · Computer Science 2018-12-24 Zhiqiang Zhao , Yongyu Wang , Zhuo Feng

This paper describes a general method for representing $k$-token graphs of Cayley graphs as lifts of voltage graphs. This allows us to construct line graphs of circulant graphs and Johnson graphs as lift graphs on cyclic groups. As an…

Combinatorics · Mathematics 2024-04-03 C. Dalfó , M. A. Fiol , S. Pavlíková , J. Širáň

This paper characterizes the graphical properties of an optimal topology with minimal Laplacian energy under the constraint of fixed numbers of vertices and edges, and devises an algorithm to construct such connected optimal graphs. These…

Optimization and Control · Mathematics 2024-03-26 Susie Lu , Ji Liu

A sign is introduced in the usual Laplacian on graphs and the corresponding analogue of the isoperimetric constant for this Laplacian is presented, i.e. a geometric quantity which enables to bound from above and below the first eigenvalue.…

Differential Geometry · Mathematics 2019-10-22 Antoine Gournay

In this work, we theoretically demonstrate that current graph positional encodings (PEs) are not beneficial and could potentially hurt performance in tasks involving heterophilous graphs, where nodes that are close tend to have different…

Machine Learning · Computer Science 2025-04-30 Michael Ito , Jiong Zhu , Dexiong Chen , Danai Koutra , Jenna Wiens

Separating multiple graph signals from a single observed mixture is an inherently ill-posed problem that traditionally relies on restrictive and handcrafted priors. This letter addresses this challenge by proposing an unsupervised learnable…

Signal Processing · Electrical Eng. & Systems 2026-04-28 Keivan Faghih Niresi , Dorina Thanou , Olga Fink

Recently, Laplacian matrices of graphs are studied as density matrices in quantum mechanics. We continue this study and give conditions for separability of generalized Laplacian matrices of weighted graphs with unit trace. In particular, we…

Quantum Physics · Physics 2007-05-23 Chai Wah Wu

This note presents a new spectral version of the graph Zarankiewicz problem: How large can be the maximum eigenvalue of the signless Laplacian of a graph of order $n$ that does not contain a specified complete bipartite subgraph. A…

Combinatorics · Mathematics 2015-07-03 Maria Aguieiras A. de Freitas , Vladimir Nikiforov , Laura Patuzzi

In this paper, we use a new and correct method to determine the $n$-vertex $k$-trees with the first three largest signless Laplacian indices.

Combinatorics · Mathematics 2015-07-23 Minjie Zhang , Shuchao Li

We give upper and lower bounds for the spectral radius of a nonnegative matrix by using its average 2-row sums, and characterize the equality cases if the matrix is irreducible. We also apply these bounds to various nonnegative matrices…

Combinatorics · Mathematics 2014-05-30 Rundan Xing , Bo Zhou

The Bridge graph is a special type of graph which are constructed by connecting identical connected graphs with path graphs. We discuss different types of bridge graphs $B_{n\times l}^{m\times k}$ in this paper. In particular, we discuss…

Combinatorics · Mathematics 2023-01-03 Yixin Li

We study here the graphs with seven vertices in an effort to classify which of them appear as the prime character degree graphs of finite solvable groups. This classification is complete for the disconnected graphs. Of the 853…

Group Theory · Mathematics 2023-08-03 Jacob Laubacher , Mark Medwid , Dylan Schuster

Laplace operators on finite compact metric graphs are considered under the assumption that matching conditions at graph vertices are of $\delta$ and $\delta'$ types. Assuming rational independence of edge lengths, necessary and sufficient…

Spectral Theory · Mathematics 2015-12-09 Yulia Ershova , Irina I. Karpenko , Alexander V. Kiselev

This paper surveys some recent results and progress on the extremal prob- lems in a given set consisting of all simple connected graphs with the same graphic degree sequence. In particular, we study and characterize the extremal graphs…

Combinatorics · Mathematics 2015-10-08 Xiao-Dong Zhang

Existing approaches to analyzing the asymptotics of graph Laplacians typically assume a well-behaved kernel function with smoothness assumptions. We remove the smoothness assumption and generalize the analysis of graph Laplacians to include…

Machine Learning · Statistics 2011-01-31 Daniel Ting , Ling Huang , Michael Jordan