A note on sum of powers of the Laplacian eigenvalues of bipartite graphs

Abstract For a graph G and a real number α ≠ 0 , the graph invariant s α ( G ) is the sum of the α th power of the non-zero Laplacian eigenvalues of G . In this note, we obtain some bounds of s α ( G ) for a connected bipartite graph G , which improve some known results of Zhou [B. Zhou, On sum of powers of the Laplacian eigenvalues of graphs, Linear Algebra Appl. 429 (2008) 2239-2246].