Affiliation: | (1) Department of Economics, The University of Western Ontario, London, Ontario, Canada, N6A 5C2; E-mail;(2) School of Economics and Management, Tsinghua University, Beijing, 100084, P.R. China; E-mail;(3) Institute of Systems Science, The Chinese Academy of Sciences, Beijing, 100080, P.R. China; E-mail;(4) Department of Computer Science, City University of Hong Kong Kowloon, Hong Kong SAR, China; E-mail |