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Extremal t‐apex trees with respect to matching energy
Authors:Kexiang Xu  Zhiqing Zheng  Kinkar Ch Das
Institution:1. Department of Mathematics, College of Science, Nanjing University of Aeronautics & Astronautics, Nanjing, Jiangsu, People's Republic of China;2. Department of Mathematics, Sungkyunkwan University, Suwon, Republic of Korea
Abstract:The matching energy of a graph is defined as the sum of the absolute values of the zeros of its matching polynomial. For any integer t≥1, a graph G is called t‐apex tree if there exists a t‐set urn:x-wiley::media:cplx21651:cplx21651-math-0001 such that G ? X is a tree, while for any urn:x-wiley::media:cplx21651:cplx21651-math-0002 with urn:x-wiley::media:cplx21651:cplx21651-math-0003, G ? Y is not a tree. Let urn:x-wiley::media:cplx21651:cplx21651-math-0004 be the set of t‐apex trees of order n. In this article, we determine the extremal graphs from urn:x-wiley::media:cplx21651:cplx21651-math-0005 with minimal and maximal matching energies, respectively. Moreover, as an application, the extremal cacti of order n and with s cycles have been completely characterized at which the minimal matching energy are attained. © 2015 Wiley Periodicals, Inc. Complexity 21: 238–247, 2016
Keywords:t‐apex tree  matching energy  quasi‐order  cactus
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