中文摘要：

Chong Long received his B.E. degree from Tsinghua University, China in 2005. He is a Ph.D. candi- date in Department of Computer Sci- ence and Technology, Tsinghua Uni- versity, China. His research interests include Kolmogorov complexity and its applications, text mining and nat- ural language processing. Min-Lie Huang now is a faculty member of Dept. Computer Science and Technology, Tsinghua University. He received his Ph.D. degree from Tsinghua University in 2006. His research interests include machine learning, natural language processing, graph-based text mining, opinion and review mining, and complex question answering. Xiao-Yan Zhu is a professor and the Deputy Head of State Key Lab of Intelligent Technology and Systems, Tsinghua University. She obtained the Bachelor＇s degree from Univer- sity of Science and Technology Bei- jing in 1982, the Master＇s degree from Kobe University in 1987, and the Ph.D. degree from Nagoya Institute of Technology, Japan in 1990.She has been teaching at Tsinghua University since 1993. Her research interests include pattern recognition, neural network, machine learning, natural language processing and bioinformatics. She is a member of CCF. Ming Li is a Canada Research Chair in Bioinformatics and a Uni- versity Professor of the University of Waterloo. He is a fellow of Royal So- ciety of Canada, ACM, and IEEE. He is a recipient of E.W.R. Steacie Fel- lowship Award in 1996, and the 2001 Killam Fellowship. Together with Paul Vitanyi they have pioneered the applications of Kolmogorov complexity and co-authored the book ＂An Introduction to Kol- mogorov Complexity and Its Applications＂. His research interests recently include protein structure determination and next generation Internet search engine.