Tien der Han Economics Division, SinoAsia Economic and Management Foundation, University of York   3F. No. 3 Alley 433 ZhongZheng R.D., New Taipei City, Hsintien District, Taiwan 23148 R.O.C.   tender38@ms45.hinet.net             JEL Areas: L1 : Market Structure, Firm Strategy, and Market Performance: General D0 : Microeconomics: General