Some graft transformations and its applications on the distance spectral radius of a graph |
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Authors: | Guanglong Yu Huicai Jia Jinlong Shu |
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Affiliation: | a Department of Mathematics, Yancheng Teachers University, Yancheng, 224002, Jiangsu, Chinab Department of Mathematics, East China Normal University, Shanghai, 200241, Chinac Department of Mathematics, Taizhou University, Taizhou, 317000, Zhejiang, Chinad Department of Mathematical and Physical Sciences, Henan Institute of Engineering, Zhengzhou, Henan, 451191, China |
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Abstract: | Let D(G)=(di,j)n×n denote the distance matrix of a connected graph G with order n, where dij is equal to the distance between vi and vj in G. The largest eigenvalue of D(G) is called the distance spectral radius of graph G, denoted by ?(G). In this paper, some graft transformations that decrease or increase ?(G) are given. With them, for the graphs with both order n and k pendant vertices, the extremal graphs with the minimum distance spectral radius are completely characterized; the extremal graph with the maximum distance spectral radius is shown to be a dumbbell graph (obtained by attaching some pendant edges to each pendant vertex of a path respectively) when 2≤k≤n−2; for k=1,2,3,n−1, the extremal graphs with the maximum distance spectral radius are completely characterized. |
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Keywords: | Graft transformation Distance spectral radius Pendant number |
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