题目： On the normalized Laplacian of graphs and related problems
摘要： In this talk, a close relation between the normalized Laplacians and some other graph invariants is displayed. Combining graph transformations and some other techniques, sharp upper and lower bounds on the cover cost (resp. reverse cover cost), the multiplicative degree-Kirchhoff index, the number of spanning trees of some graphs are, respectively, determined. All the corresponding extremal graphs are identified.