中文摘要：

Lei Jia received his B.E. and M.B. degrees in computer science from Tianjin University of China in 2004 and 2007 respectively. Cur- rently he is a Ph.D. candidate at School of Computer Science and Technology, Tianjin University. His research interests include machine learning, model selection and kernel methods. Shi-Zhong Liao is a professor and Ph.D. supervisor at School of Computer Science and Technology, Tianjin University. He is a member of CCF. He received the Ph.D. degree in computer science from Tsinghua University in 1997. His research interests include artificial intelligence and theoretical computer science. Li-Zhong Ding received his B.E. degree in computer science from Tianjin University of China in 2009. Currently he is a Ph.D. candidate at School of Computer Science and Technology, Tianjin University. His research interests include computa- tional learning theory, model selection and kernel methods.