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The $g$-component edge connectivity $c\lambda_g(G)$ of a non-complete graph $G$ is the minimum number of edges whose deletion results in a graph with at least $g$ components. In this paper, we determine the component edge connectivity of…

Combinatorics · Mathematics 2018-03-06 Shuli Zhao , Weihua Yang

The independence complex of a graph $G=(V,E)$ is the simplicial complex $I(G)$ on vertex set $V$ whose simplices are the independent sets in $G$. We present new lower bounds on the eigenvalues of the $k$-dimensional Laplacian $L_k(I(G))$ in…

Combinatorics · Mathematics 2024-12-19 Alan Lew

Let $G$ be a graph with adjacency matrix $A(G)$ and Laplacian matrix $L(G)$. In 2024, Samanta \textit{et} \textit{al.} defined the convex linear combination of $A(G)$ and $L(G)$ as $B_\alpha(G) = \alpha A(G) + (1-\alpha)L(G)$, for $\alpha…

Discrete Mathematics · Computer Science 2025-10-21 Germain Pastén , Carla Silva Oliveira , João Domingos G. da Silva Junior , Claudia M. Justel

For a connected graph $G$, we denote by $L(G)$, $m_{G}(\lambda)$, $c(G)$ and $p(G)$ the line graph of $G$, the eigenvalue multiplicity of $\lambda$ in $G$, the cyclomatic number and the number of pendant vertices in $G$, respectively. In…

Spectral Theory · Mathematics 2024-12-24 Wenhao Zhen , Dein Wong , Songnian Xu

A non-zero component graph $G(\mathbb{V})$ associated to a finite vector space $\mathbb{V}$ is a graph whose vertices are non-zero vectors of $\mathbb{V}$ and two vertices are adjacent, if their corresponding vectors have at least one…

Combinatorics · Mathematics 2019-08-06 I. Javaid , M. Murtaza , H. Benish

Let $k$ be a positive integer and let $G$ be a simple graph of order $n$ with minimum degree $\delta$. A graph $G$ is said to have property $P(k, d)$ if it contains $k$ edge-disjoint spanning trees and an additional forest $F$ with edge…

Combinatorics · Mathematics 2026-01-14 Yongbin Gao , Ligong Wang

We study the operator theory associated with such infinite graphs $G$ as occur in electrical networks, in fractals, in statistical mechanics, and even in internet search engines. Our emphasis is on the determination of spectral data for a…

Mathematical Physics · Physics 2009-11-13 Palle E. T. Jorgensen

In this paper, we show that a uniform hypergraph $\mathcal{G}$ is connected if and only if one of its inverse Perron values is larger than $0$. We give some bounds on the bipartition width, isoperimetric number and eccentricities of…

Combinatorics · Mathematics 2017-11-28 Changjiang Bu , Haifeng Li , Jiang Zhou

For a graph $G$, let $\lambda_2(G)$ denote its second smallest Laplacian eigenvalue. It was conjectured that $\lambda_2(G) + \lambda_2(\overline{G}) \geq 1$, where $\bar{G}$ is the complement of $G$. Here, we prove this conjecture in the…

Combinatorics · Mathematics 2021-06-25 Mostafa Einollahzadeh , Mohammad Mahdi Karkhaneei

In this paper we show that the $d$-dimensional algebraic connectivity of an arbitrary graph $G$ is bounded above by its $1$-dimensional algebraic connectivity, i.e., $a_d(G) \leq a_1(G)$, where $a_1(G)$ corresponds the well-studied second…

Combinatorics · Mathematics 2022-09-30 Juan F. Presenza , Ignacio Mas , Juan I. Giribet , J. Ignacio Alvarez-Hamelin

The edge-connectivity of a graph is the minimum number of edges whose deletion disconnects the graph. Let $\Delta(G)$ the maximum degree of a graph $G$ and let $\rho(G)$ be the spectral radius of $G$. In this article we present a lower…

Combinatorics · Mathematics 2019-11-20 Cristian Conde , Ezequiel Dratman , Luciano N. Grippo

Let $G$ be a connected non-odd-bipartite hypergraph with even uniformity. The least H-eigenvalue of the signless Laplacian tensor of $G$ is simply called the least eigenvalue of $G$ and the corresponding H-eigenvectors are called the first…

Combinatorics · Mathematics 2021-08-31 Yi-Zheng Fan , Jiang-Chao Wan , Yi Wang

Let $G$ be a connected graph. The edge-connectivity of $G$, denoted by $\lambda(G)$, is the minimum number of edges whose removal renders $G$ disconnected. Let $\delta(G)$ be the minimum degree of $G$. It is well-known that $\lambda(G) \leq…

Combinatorics · Mathematics 2024-08-20 Camino Balbuena , Peter Dankelmann

Let $\mathbb{Q}_{k,n}$ be the set of the connected $k$-uniform weighted hypergraphs with $n$ vertices, where $k,n\geq 3$. For a hypergraph $G\in \mathbb{Q}_{k,n}$, let $\mathcal{A}(G)$, $\mathcal{L} (G)$ and $\mathcal{Q} (G)$ be its…

Combinatorics · Mathematics 2022-03-01 Rui Sun , Wen-Huan Wang

It is well known that the algebraic multiplicity of an eigenvalue of a graph (or real symmetric matrix) is equal to the dimension of its corresponding linear eigen-subspace, also known as the geometric multiplicity. However, for…

Combinatorics · Mathematics 2025-03-28 Changjiang Bu , Lixiang Chen , Yongtang Shi

A signless Laplacian eigenvalue of a graph $G$ is called a main signless Laplacian eigenvalue if it has an eigenvector the sum of whose entries is not equal to zero. In this paper, all connected bicyclic graphs with exactly two main…

Combinatorics · Mathematics 2013-10-10 He Huang , Hanyuan Deng

As a generalization of the traditional connectivity, the g-component edge connectivity c{\lambda}g(G) of a non-complete graph G is the minimum number of edges to be deleted from the graph G such that the resulting graph has at least g…

Combinatorics · Mathematics 2021-05-12 Dong Liu , Pingshan Li , Bicheng Zhang

Let $G$ be a simple graph with adjacency matrix $A(G)$, signless Laplacian matrix $Q(G)$, degree diagonal matrix $D(G)$ and let $l(G)$ be the line graph of $G$. In 2017, Nikiforov defined the $A_\alpha$-matrix of $G$, $A_\alpha(G)$, as a…

Discrete Mathematics · Computer Science 2024-02-26 Joao Domingos Gomes da Silva Junior , Carla Silva Oliveira , Liliana Manuela Gaspar C. da Costa

For each uniformity $k \geq 3$, we construct $k$-uniform linear hypergraphs $G$ with arbitrarily large maximum degree $\Delta$ whose independence polynomial $Z_G$ has a root $\lambda$ with $\lvert\lambda\rvert = O\left(\frac{\log…

Combinatorics · Mathematics 2025-07-02 Shengtong Zhang

In this study, we explore the interrelation between hypergraph symmetries represented by equivalence relations on the vertex set and the spectra of operators associated with the hypergraph. We introduce the idea of equivalence relation…

Combinatorics · Mathematics 2024-10-25 Anirban Banerjee , Samiron Parui