First Author:   Terence T. L. Chong Dept of Economics, Chinese Univ of Hong Kong and Dept of Int''l Economics and Trade, Nanjing Univ chong2064@cuhk.edu.hk   Department of Economics, The Chinese University of Hong Kong, Shatin, N.T., , Hong Kong   852-39438193(Phone) 852-39438193(Fax) http://www.cuhk.edu.hk/eco/staff/tlchong/tlchong3.htm Second Author: Kim man Lui Department of Computing, The Hong Kong Polytechnic University cskmlui@comp.polyu.edu.hk