Let $ G $ be a simple connected graph of order $ n $ with $ m $ edges. The energy $ \varepsilon(G) $ of $ G $ is the sum of the absolute values of all eigenvalues of the adjacency matrix $ A $. The Laplacian energy is defined as $ LE(G) = \sum_{i = 1}^{n}|\mu_{i}-\frac{2m}{n}| $, where $ \mu_{1}, \mu_{2}, \dots, \mu_{n} $ are the Laplacian eigenvalues of a graph $ G $. In this article, we obtain some upper and lower bounds on the energy and Laplacian energy of chain graph. Finally, we attain the maximal Laplacian energy among all connected bicyclic chain graphs by comparing algebraic connectivity.
Citation: Yinzhen Mei, Chengxiao Guo, Mengtian Liu. The bounds of the energy and Laplacian energy of chain graphs[J]. AIMS Mathematics, 2021, 6(5): 4847-4859. doi: 10.3934/math.2021284
Let $ G $ be a simple connected graph of order $ n $ with $ m $ edges. The energy $ \varepsilon(G) $ of $ G $ is the sum of the absolute values of all eigenvalues of the adjacency matrix $ A $. The Laplacian energy is defined as $ LE(G) = \sum_{i = 1}^{n}|\mu_{i}-\frac{2m}{n}| $, where $ \mu_{1}, \mu_{2}, \dots, \mu_{n} $ are the Laplacian eigenvalues of a graph $ G $. In this article, we obtain some upper and lower bounds on the energy and Laplacian energy of chain graph. Finally, we attain the maximal Laplacian energy among all connected bicyclic chain graphs by comparing algebraic connectivity.
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