Some graft transformations and its application on a distance spectrum |
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Authors: | Guanglong Yu Yarong Wu Yajie Zhang Jinlong Shu |
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Institution: | aDepartment of Mathematics, Yancheng Teachers University, Yancheng, 224002, Jiangsu, PR China;bDepartment of Mathematics, East China Normal University, Shanghai, 200241, China;cSMU College of Art and Science, Shanghai Maritime University, Shanghai, 200135, 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, we give some graft transformations that decrease and increase ?(G) and prove that the graph (obtained from the star Sn on n (n is not equal to 4, 5) vertices by adding an edge connecting two pendent vertices) has minimal distance spectral radius among unicyclic graphs on n vertices; while (obtained from a triangle K3 by attaching pendent path Pn−3 to one of its vertices) has maximal distance spectral radius among unicyclic graphs on n vertices. |
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Keywords: | Graft transformation Distance spectral radius Unicyclic graph |
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