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Keywords

Graph, Spectral radius, Energy, Laplacian energy, First Zagreb index, Determinant.

Abstract

Let $G=(V,E)$ be a simple graph of order $n$ with $m$ edges. The energy of a graph $G$, denoted by $\mathcal{E}(G)$, is defined as the sum of the absolute values of all eigenvalues of $G$. The Laplacian energy of the graph $G$ is defined as $LE = LE(G)=\sum^n_{i=1}\left|\mu_i-\frac{2m}{n}\right|$ where $\mu_1,\,\mu_2,\,\ldots,\,\mu_{n-1},\,\mu_n=0$ are the Laplacian eigenvalues of graph $G$. In this paper, some lower and upper bounds for $\mathcal{E}(G)$ are presented in terms of number of vertices, number of edges, maximum degree and the first Zagreb index, etc. Moreover, a relation between energy and Laplacian energy of graphs is given.

abs_vol31_pp167-186.pdf (30 kB)
Abstract

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