研究了删点集对图的无符号拉普拉斯谱(Q-谱)的影响,给出了删点集插值定理.进一步,得到了一个下界q_i(G)≥d_i-i+1(i=1,2,…,n),其中q_i(G)为n阶图G的第i大Q-特征值,d_i为第i大顶点度.另外,给出了q_i(G)≥d_i-1(i=2,…,k)成立的一个充分条件,以及等号成立的必要条件等.
The authors study the signless Laplacian spectra(Q-spectra) of graphs,and show an interlacing relation between a graph and its subgraph which is obtained by vertices deleting.Moreover, bounds that qi(G)≥d_i-i+1(i = 1,2,...,n) are given,where qi(G) denotes the i-th largest Qeigenvalue of the graph G of order n,and d_i denotes the i-th largest degree.Also,the sufficient condition for qi(G)≥d_i-1(i = 2,...,k) and the necessary conditions for the equalities are given.