设G为n阶简单连通单圈图,λn-1(G)为G的次小特征值,给出了同构于Sn^3的G的次小特征值及λn-1(G)的一个上界.
Let G be a simple connected unicyclic graph. λn-1 (G) denotes the second smallest eigenvalue of the unicyclic graph G. In this paper, the authors obtain a second smallest eigenvalue of graph G ( isomorphic graph Sn^3. ), and a sharp upper bounds of λn-1 ( G ).