Du Zhibin
School of Mathematics and Statistics, Zhaoqing University, Zhaoqing, 526061 China.
J Inequal Appl. 2017;2017(1):96. doi: 10.1186/s13660-017-1367-2. Epub 2017 May 3.
The eigenvalues of are denoted by [Formula: see text], where is the order of . In particular, [Formula: see text] is called the spectral radius of , [Formula: see text] is the least eigenvalue of , and the spread of is defined to be the difference between [Formula: see text] and [Formula: see text]. Let [Formula: see text] be the set of -vertex unicyclic graphs, each of whose vertices on the unique cycle is of degree at least three. We characterize the graphs with the th maximum spectral radius among graphs in [Formula: see text] for [Formula: see text] if [Formula: see text], [Formula: see text] if [Formula: see text], and [Formula: see text] if [Formula: see text], and the graph with minimum least eigenvalue (maximum spread, respectively) among graphs in [Formula: see text] for [Formula: see text].
的特征值记为[公式:见正文],其中 是 的阶数。特别地,[公式:见正文]称为 的谱半径,[公式:见正文]是 的最小特征值,并且 的展布定义为[公式:见正文]与[公式:见正文]的差。设[公式:见正文]是 -顶点单圈图的集合,其唯一圈上的每个顶点的度数至少为三。对于[公式:见正文],我们刻画了在[公式:见正文]中的图中具有第 大谱半径的图(如果[公式:见正文]),[公式:见正文](如果[公式:见正文]),以及[公式:见正文](如果[公式:见正文]),并且对于[公式:见正文],刻画了在[公式:见正文]中的图中具有最小最小特征值(分别为最大展布)的图。