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{Signless Laplacian determinations of some graphs with independent edges}% {Let $G$ be a simple undirected graph. Then the signless Laplacian matrix of $G$ is defined as $D_G + A_G$ in which $D_G$ and $A_G$ denote the degree matrix and the…

组合数学 · 数学 2018-03-19 R. Sharafdini , A. Z. Abdian

Let $G$ be a graph and $T$ be a spanning tree of $G$. We use $Q(G)=D(G)+A(G)$ to denote the signless Laplacian matrix of $G$, where $D(G)$ is the diagonal degree matrix of $G$ and $A(G)$ is the adjacency matrix of $G$. The signless…

组合数学 · 数学 2026-03-24 Jiancheng Wu , Sizhong Zhou , Hongxia Liu

A graph is said to be determined by its signless Laplacian spectrum (abbreviated as DQS) if no other non-isomorphic graph shares the same signless Laplacian spectrum. In this paper, we establish the following results: (1). Every graph of…

组合数学 · 数学 2025-08-24 Jiachang Ye , Zoran Stanić , Jianguo Qian

For two simple graphs $G_1$ and $G_2$, we denote the subdivision-vertex join and subdivision-edge join of $G_1$ and $G_2$ by $G_1\dot{\vee}G_2$ and $G_1\veebar G_2$, respectively. This paper determines the normalized Laplacian spectra of…

组合数学 · 数学 2017-03-21 Gui-xian Tian , Shu-Yu Cui

Due to the limited resources and the scale of the graphs in modern datasets, we often get to observe a sampled subgraph of a larger original graph of interest, whether it is the worldwide web that has been crawled or social connections that…

机器学习 · 计算机科学 2018-12-04 Ashish Khetan , Harshay Shah , Sewoong Oh

Exact eigendecomposition of large matrices is very expensive, and it is practically impossible to compute exact eigenvalues. Instead, one may set a more modest goal of approaching the empirical distribution of the eigenvalues, recovering…

A spanning tree of a graph is a connected subgraph on all vertices with the minimum number of edges. The number of spanning trees in a graph $G$ is given by Matrix Tree Theorem in terms of principal minors of Laplacian matrix of $G$. We…

组合数学 · 数学 2018-05-15 Keivan Hassani Monfared , Sudipta Mallik

In this paper, we determine the maximal Laplacian and signless Laplacian spectral radii for graphs with fixed number of vertices and domination number, and characterize the extremal graphs respectively.

组合数学 · 数学 2013-10-29 Rundan Xing , Bo Zhou

For a simple graph $G$, the generalized adjacency matrix $A_{\alpha}(G)$ is defined as $A_{\alpha}(G)=\alpha D(G)+(1-\alpha)A(G), \alpha\in [0,1]$, where $A(G)$ is the adjacency matrix and $D(G)$ is the diagonal matrix of vertex degrees of…

组合数学 · 数学 2021-10-26 Bilal A. Rather , Hilal A. Ganie , S. Pirzada

Graph neural networks have developed by leaps and bounds in recent years due to the restriction of traditional convolutional filters on non-Euclidean structured data. Spectral graph theory mainly studies fundamental graph properties using…

谱理论 · 数学 2023-09-08 Xinye Chen

In finite group theory, studying the prime graph of a group has been an important topic for almost the past half-century. Recently, prime graphs of solvable groups have been characterized in graph theoretical terms only. This now allows the…

组合数学 · 数学 2020-11-19 Chris Florez , Jonathan Higgins , Kyle Huang , Thomas Michael Keller , Dawei Shen

The eccentricity matrix of a simple connected graph is derived from its distance matrix by preserving the largest non-zero distance in each row and column, while the other entries are set to zero. This article examines the…

组合数学 · 数学 2024-11-20 Anjitha Ashokan , Chithra A

A vertex of degree one in a tree is called an end vertex and a vertex of degree at least three is called a branch vertex. For a graph $G$, let $\sigma_2$ be the minimum degree sum of two nonadjacent vertices in $G$. We consider tree…

组合数学 · 数学 2015-05-19 Zhora Nikoghosyan

In this paper we explore some results concerning the spread of the line and the total graph of a given graph. In particular, it is proved that for an $(n,m)$ connected graph $G$ with $m > n \geq 4$ the spread of $G$ is less than or equal to…

谱理论 · 数学 2018-07-10 E. Andrade , E. Lenes , E. Mallea , M. Robbiano , Jonnathan Rodríguez

A matching M is a dominating induced matching of a graph, if every edge of the graph is either in $M$ or has a common end-vertex with exactly one edge in $M$. The concept of complete dominating induced matching is introduced as graphs where…

组合数学 · 数学 2013-11-13 Domingos M. Cardoso , Enide A. Martins , Luís Medina , Oscar Rojo

A new measure to assess the centrality of vertices in an undirected and connected graph is proposed. The proposed measure, L1 centrality, can adequately handle graphs with weights assigned to vertices and edges. The study provides tools for…

统计方法学 · 统计学 2024-04-23 Seungwoo Kang , Hee-Seok Oh

In this paper, we present a sharp upper and lower bounds for the signless Laplacian spectral radius of graphs in terms of clique number. Moreover, the extremal graphs which attain the upper and lower bounds are characterized. In addition,…

组合数学 · 数学 2012-09-17 Bian He , Ya-Lei Jin , Xiao-Dong Zhang

In this paper, we present several upper bounds for the adjacency and signless Laplacian spectral radii of uniform hypergraphs in terms of degree sequences.

组合数学 · 数学 2017-02-22 Dongmei Chen , Zhibing Chen , Xiao-Dong Zhang

Let $G$ be a connected graph and let $k$ be a positive integer. Let $T$ be a spanning tree of $G$. The leaf degree of a vertex $v\in V(T)$ is defined as the number of leaves adjacent to $v$ in $T$. The leaf degree of $T$ is the maximum leaf…

组合数学 · 数学 2024-06-12 Sufang Wang , Wei Zhang

We generalize the concept of token graphs to obtain supertoken graphs. In the latter case, there can be more than one token in a vertex. We formally define supertoken graphs and establish their basic properties. Moreover, we provide some…

组合数学 · 数学 2026-04-08 Mónica A. Reyes , Cristina Dalfó , Miquel Àngel Fiol