The Signless Laplacian Spectral Radius of Tricyclic Graphs with a Given Girth
Received:May 25, 2013  Revised:November 13, 2013
Key Words: tricyclic graph   signless Laplacian spectral radius   girth.  
Fund Project:Supported by the National Natural Science Foundation of China (Grant No.11171273).
Author NameAffiliation
Lu QIAO Department of Applied Mathematics, School of Science, Northwestern Polytechnical University, Shaanxi 710072, P. R. China 
Ligong WANG Department of Applied Mathematics, School of Science, Northwestern Polytechnical University, Shaanxi 710072, P. R. China 
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Abstract:
      A tricyclic graph $G=(V(G),E(G))$ is a connected and simple graph such that $|E(G)|=|V(G)|+2$. Let $\mathscr{T}_n^g$ be the set of all tricyclic graphs on $n$ vertices with girth $g$. In this paper, we will show that there exists the unique graph which has the largest signless Laplacian spectral radius among all tricyclic graphs with girth $g$ containing exactly three (resp., four) cycles. And at the same time, we also give an upper bound of the signless Laplacian spectral radius and the extremal graph having the largest signless Laplacian spectral radius in $\mathscr{T}_n^g$, where $g$ is even.
Citation:
DOI:10.3770/j.issn:2095-2651.2014.04.001
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