中文摘要：

Peng Zhang is an associate professor of computer science at the School of Computer Science and Technology, Shandong University, China. He received his PhD in computer science from the Institute of Software, Chinese Academy of Sciences in 2007. His research interests include approximation algorithms, combinatorial optimization, and computational com- plexity. He has published more than twenty papers, mainly in ap- proximation algorithms, in journals such as Theory of Computing Systems, Discrete Applied Mathematics, Theoretical Computer Science, and in conferences such as ISAAC, LATIN, COCOA, and TAMC.E-mail： algzhang@sdu.edu.cn, zhangpeng@mail.sdu.edu.cn