Graph spectrum;
Energy (of graph);
Laplacian energy (of graph);
Singular value of matrix;
Ky Fan theorem;
Adjacency matrix;
Laplacian matrix;
Bethe trees;
MATRIX;
EIGENVALUES;
D O I:
10.1016/j.laa.2009.03.047
中图分类号:
O29 [应用数学];
学科分类号:
070104 ;
摘要:
For k, d >= 2, a Bethe tree is a rooted tree with k levels which the root vertex has degree d, the vertices from level 2 to k - 1 have degree d + 1 and the vertices at the level k are pendent vertices. So et al., using a theorem by Ky Fan have obtained both upper and lower bounds for the Laplacian energy of bipartite graphs. We shall employ the above mentioned theorem to obtain new and improved bounds for the Laplacian energy in the case of Bethe trees. (C) 2009 Elsevier Inc. All rights reserved.