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For a $hypergraph$ $\mathcal{G}=(V, E)$ consisting of a nonempty vertex set $V=V(\mathcal{G})$ and an edge set $E=E(\mathcal{G})$, its $adjacency$ $matrix$ $\mathcal {A}_{\mathcal{G}}=[(\mathcal {A}_{\mathcal{G}})_{ij}]$ is defined as…

Combinatorics · Mathematics 2023-07-14 Guanglong Yu , Lin Sun

Let $G$ be a $k$-uniform hypergraph with vertex set $V(G)$ and edge set $E(G)$. A connected and acyclic hypergraph is called a supertree. For $0\leq\alpha<1$, the $\alpha$-spectral radius of $G$ is the largest $H$-eigenvalue of $\alpha…

Combinatorics · Mathematics 2022-06-08 Chang Liu , Jianping Li

The transmission of a connected hypergraph is defined as the summation of distances between all unordered pairs of distinct vertices. We determine the unique uniform unicyclic hypergraphs of fixed size with minimum and maximum…

Combinatorics · Mathematics 2018-10-25 Hongying Lin , Bo Zhou

For real $\alpha\in [0,1)$ and a hypergraph $G$, the $\alpha$-spectral radius of $G$ is the largest eigenvalue of the matrix $A_{\alpha}(G)=\alpha D(G)+(1-\alpha)A(G)$, where $A(G)$ is the adjacency matrix of $G$, which is a symmetric…

Discrete Mathematics · Computer Science 2023-03-30 Haiyan Guo , Bo Zhou , Bizhu Lin

The spectral radius (or the signless Laplacian spectral radius) of a general hypergraph is the maximum modulus of the eigenvalues of its adjacency (or its signless Laplacian) tensor. In this paper, we firstly obtain a lower bound of the…

Combinatorics · Mathematics 2020-07-28 Cunxiang Duan , Ligong Wang

For a $hypergraph$ $\mathcal{G}=(V, E)$ with a nonempty vertex set $V=V(\mathcal{G})$ and an edge set $E=E(\mathcal{G})$, its $adjacency$ $matrix$ $\mathcal {A}_{\mathcal{G}}=[(\mathcal {A}_{\mathcal{G}})_{ij}]$ is defined as $(\mathcal…

Combinatorics · Mathematics 2023-07-19 Guanglong Yu

For $0\leq \alpha < 1$, the $\mathcal{A}_{\alpha}$-spectral radius of a $k$-uniform hypergraph $G$ is defined to be the spectral radius of the tensor $\mathcal{A}_{\alpha}(G):=\alpha \mathcal{D}(G)+(1-\alpha) \mathcal{A}(G)$, where…

Combinatorics · Mathematics 2021-09-09 Peng-Li Zhang , Xiao-Dong Zhang

It is well-known that the spectral radius of a connected uniform hypergraph is an eigenvalue of the hypergraph. However, its algebraic multiplicity remains unknown. In this paper, we use the Poisson Formula and matching polynomials to…

Combinatorics · Mathematics 2023-06-30 Lixiang Chen , Changjiang Bu

Let $G$ be a graph. We say that a hypergraph $H$ is a Berge-$G$ if there is a bijection $\phi: E(G)\to E(H)$ such that $e\subseteq \phi(e)$ for all $e\in E(G)$. For any $r$-uniform hypergraph $H$ and a real number $p\geq 1$, the…

Combinatorics · Mathematics 2018-12-19 Liying Kang , Lele Liu , Linyuan Lu , Zhiyu Wang

In this paper, we give some bounds for principal eigenvector and spectral radius of connected uniform hypergraphs in terms of vertex degrees, the diameter, and the number of vertices and edges.

Combinatorics · Mathematics 2016-05-30 Haifeng Li , Jiang Zhou , Changjiang Bu

Consider a group $\mathbb{G}$ and construct its power graph, whose vertex set consists of the elements of $\mathbb{G}$. Two distinct vertices (elements) are adjacent in the graph if and only if one element can be expressed as an integral…

Spectral Theory · Mathematics 2026-03-03 Priti Prasanna Mondal , Basit Auyoob Mir , Fouzul Atik

A signed graph is a graph in which every edge carries a $+$ or a $-$ sign. In this paper, we determine the signed graphs with maximum spectral radius among all unbalanced signed graphs with fixed order that contain neither negative…

Combinatorics · Mathematics 2024-07-24 Yiting Cai , Bo Zhou

The square of a connected graph $G$ is obtained from $G$ by adding an edge between every pair of vertices at distance $2$. In this paper we give some upper or lower bounds for the spectral radius of the square of connected graphs, trees and…

Combinatorics · Mathematics 2014-04-30 Yi-Zheng Fan , Long Wang

In this paper we show how the $\alpha$-spectral radius changes under the edge grafting operations on connected $k$-uniform hypergraphs. We characterize the extremal hypertree for $\alpha$-spectral radius among $k$-uniform non-caterpillar…

Combinatorics · Mathematics 2019-05-21 Feifei Wang , Haiying Shan , Zhiyi Wang

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

In this paper, we investigate spectral properties of the adjacency tensor, Laplacian tensor and signless Laplacian tensor of general hypergraphs (including uniform and non-uniform hypergraphs). We obtain some bounds for the spectral radius…

Combinatorics · Mathematics 2016-05-20 Changjiang Bu , Jiang Zhou , Lizhu Sun

A graph on $2k+1$ vertices consisting of $k$ triangles which intersect in exactly one common vertex is called a $k$-fan and denoted by $F_k$. This paper aims to determine the graphs of order $n$ that have the maximum (adjacency) spectral…

Combinatorics · Mathematics 2019-12-02 Sebastian Cioaba , Lihua Feng , Michael Tait , Xiao-Dong Zhang

We characterize the r-graph with maximal p-spectral radius among the k-partite r-graphs of order n, and the 3-graph with maximal p-spectral radius among the k-chromatic 3-graphs of order n.

Combinatorics · Mathematics 2014-02-11 L. Kang , V. Nikiforov , X Yuan

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

Combinatorics · Mathematics 2017-02-22 Dongmei Chen , Zhibing Chen , Xiao-Dong Zhang

In this paper, using the theory of matching polynomial of hypertrees and ordering of hypertrees, we determine the largest spectral radius of hypertrees with $m$ edges and given size of matching.

Combinatorics · Mathematics 2018-10-16 Li Su , Liying Kang , Honghai Li , Erfang Shan