Toshikazu Ohsawa Hiroshima University   403,38,1,1-chome,Minami-machi, ,Minami-ku, Hiroshima-shi,, Hiroshima-ken Japan   oosawa@hiroshima-u.ac.jp             JEL Areas: H2 : Taxation, Subsidies, and Revenue: General D6 : Welfare Economics: General