Journal of East China Normal University(Natural Sc ›› 2015, Vol. 2015 ›› Issue (1): 126-130.doi: 10.3969/j.issn.1000-5641.2015.01.015

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On limit points of the third largest Laplacian eigenvalues of graphs

 WU  Ya-Rong   

  1. College of Arts and Sciences, Shanghai Maritime University, Shanghai 201306, China
  • Received:2014-04-01 Online:2015-01-25 Published:2015-03-29

Abstract: For a different parameter $b$, let $l_G(b)$ denote the second largest root of $b\mu(\mu-2)\!-\!(\mu-1)^2(\mu-3)\!=\!0$ $(b\!=\!0,1,\cdots)$ and $l_T(b)$ denote the second largest root of $b\mu(\mu-2)\!-\!(\mu-1)^2(\mu-3)\!-\!(\mu-1)(\mu-2)\!=\!0$$(b\!=\!0,1,\cdots)$. Firstly, we will prove that there exist sequences of graphs  $\{G_{n,b}\}(b\!=\!0,1,\cdots)$ and $\{T_{n,b}\}(b\!=\!0,1,\cdots)$ such that their limit points of the third largest Laplacian eigenvalues are $l_G(b)$ and $l_T(b)$, respectively. Secondly, we will prove that $l_G(b)$, $l_T(b)$ and $2$ are all of the limit points of the third largest Laplacian eigenvalues which are no more than 2

Key words: Laplacian eigenvalue, characteristic polynomial, limit point

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