Wang Xiaofeng, born in 1978, a Ph.D candidate in Institute of Computing Technology, Chinese Academy of Sciences. He also received his B.S. and M.S. degrees from Yunnan University in 2001 and 2004 respectively. His current research interests include logic based reasoning, data mining, machine learning, semantic web, multi-agent systems, and action planning, cognitive science. To whom correspondence should be acldressed. E-mail:shizz@ics.ict.ac.cn Received on Apr. 13, 2010