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We study the problem of generating graphs with prescribed degree sequences for bipartite, directed, and undirected networks. We first propose a sequential method for bipartite graph generation and establish a necessary and sufficient…

Methodology · Statistics 2026-03-13 Tong Sun , Jianshu Hao , Michael C. Fu , Guangxin Jiang

Let $Q(G)=D(G)+A(G)$ be the signless Laplacian matrix of a simple graph of order $n$, where $D(G)$ and $A(G)$ are the degree diagonal matrix and the adjacency matrix of $G$, respectively. In this paper, we present a sharp upper bound for…

Combinatorics · Mathematics 2022-09-08 Ming-Zhu Chen , Zhao-Ming Li , Xiao-Dong Zhang

A signed graph is said to be sign-symmetric if it is switching isomorphic to its negation. Bipartite signed graphs are trivially sign-symmetric. We give new constructions of non-bipartite sign-symmetric signed graphs. Sign-symmetric signed…

Combinatorics · Mathematics 2020-03-24 Ebrahim Ghorbani , Willem H. Haemers , Hamid Reza Maimani , Leila Parsaei Majd

We consider a non self-adjoint Laplacian on a directed graph with non symmetric edge weights. We analyse spectral properties of this Laplacian under a Kirchhoff assumption. Moreover we establish isoperimet-ric inequalities in terms of the…

Spectral Theory · Mathematics 2018-01-15 Marwa Balti

We consider the class of simple graphs with large algebraic connectivity (the second-smallest eigenvalue of the Laplacian matrix). For this class of graphs we determine the asymptotic behavior of the number of Eulerian orientations. In…

Combinatorics · Mathematics 2013-06-10 Mikhail Isaev

A signed graph product is defined for a new product, and initially the unsigned graph product's Laplacian spectrum and signless Laplacian spectrum are found. Next, for the signed graph product, the adjacency spectrum, Laplacian spectrum,…

Combinatorics · Mathematics 2024-05-16 Bishal Sonar , Ravi Srivastava

In this paper, we present GGSD, a novel graph generative model based on 1) the spectral decomposition of the graph Laplacian matrix and 2) a diffusion process. Specifically, we propose to use a denoising model to sample eigenvectors and…

Machine Learning · Computer Science 2025-03-05 Giorgia Minello , Alessandro Bicciato , Luca Rossi , Andrea Torsello , Luca Cosmo

In this paper, first, we establish a sufficient condition for a bipartite graph to be Hamilton-connected. Furthermore, we also give two sufficient conditions on distance signless Laplacian spectral radius for a graph to be…

Combinatorics · Mathematics 2016-10-25 Qiannan Zhou , Ligong Wang

The $\mathcal{Q}$-graph of a graph $G$, denoted by $\mathcal{Q}(G)$, is the graph derived from $G$ by plugging a new vertex to each edge of $G$ and adding a new edge between two new vertices which lie on adjacent edges of $G$. In this…

Combinatorics · Mathematics 2021-08-04 Xiao-Qin Zhang , Shu-Yu Cui , Gui-Xian Tian

M. Aouchiche and P. Hansen proposed the distance Laplacian and the distance signless Laplacian of a connected graph [Two Laplacians for the distance matrix of a graph, LAA 439 (2013) 21{33]. In this paper, we obtain three theorems on the…

Combinatorics · Mathematics 2013-08-16 Wenxi Hong , Lihua You

In this paper we deal with a subclass of chordal graphs, which are simultaneously strictly chordal and interval, the strictly interval graphs. We present a new characterization of the class that leads to a simple linear recognition…

Discrete Mathematics · Computer Science 2026-05-19 Claudia Justel , Lilian Markenzon

In this paper, we investigate (signless) Laplacian spectral characterization of graphs with star components. Also, we prove that the join graph ${\small K_{n-\alpha}-e\vee \alpha K_{1}}$ is $DQS$ for $n-\alpha >3$ and $\alpha\neq3$, and for…

Combinatorics · Mathematics 2019-12-10 Rakshith B. R

The concept of the integrated adjacency matrix for mixed graphs was first introduced in [9], where its spectral properties were analyzed in relation to the structural characteristics of the mixed graph. Building upon this foundation, this…

Combinatorics · Mathematics 2025-07-08 G. Kalaivani , R. Rajkumar

We argue that the standard graph Laplacian is preferable for spectral partitioning of signed graphs compared to the signed Laplacian. Simple examples demonstrate that partitioning based on signs of components of the leading eigenvectors of…

Data Structures and Algorithms · Computer Science 2018-04-02 Andrew V. Knyazev

We show that, with very high probability, the random graph Laplacian has simple spectrum. Our method provides a quantitatively effective estimate of the spectral gaps. Along the way, we establish results on affine no-gaps delocalization,…

Probability · Mathematics 2025-03-18 Nicholas Christoffersen , Kyle Luh , Hoi H. Nguyen , Jingheng Wang

It is shown that there are infinitely many connected vertex-transitive graphs that have no Hamilton decomposition, including infinitely many Cayley graphs of valency 6, and including Cayley graphs of arbitrarily large valency.

Combinatorics · Mathematics 2014-11-13 Darryn Bryant , Matthew Dean

Multiscale transforms designed to process analog and discrete-time signals and images cannot be directly applied to analyze high-dimensional data residing on the vertices of a weighted graph, as they do not capture the intrinsic geometric…

Information Theory · Computer Science 2016-03-16 David I Shuman , Mohammad Javad Faraji , Pierre Vandergheynst

We show several sharp upper and lower bounds for the sum of the largest eigenvalues of the signless Laplacian matrix. These bounds improve and extend previously known bounds.

Combinatorics · Mathematics 2022-10-10 Aida Abiad , Leonardo de Lima , Sina Kalantarzadeh , Mona Mohammadi , Carla Oliveira

The work in this thesis concerns the investigation of eigenvalues of the Laplacian matrix, normalized Laplacian matrix, signless Laplacian matrix and distance signless Laplacian matrix of graphs. In Chapter 1, we present a brief…

Combinatorics · Mathematics 2021-07-21 Bilal A. Rather

We consider the problem of finding universal bounds of "isoperimetric" or "isodiametric" type on the spectral gap of the Laplacian on a metric graph with natural boundary conditions at the vertices, in terms of various analytical and…

Spectral Theory · Mathematics 2016-08-24 James B. Kennedy , Pavel Kurasov , Gabriela Malenova , Delio Mugnolo