[1] IDEI et GREMAQ,
[2] Université de Toulouse,undefined
[3] Allée de Brienne 21,undefined
[4] 31000 Toulouse,undefined
[5] France (Fax: +33-5-61128637; e-mail: helmut@cict.fr),undefined
[6] Department of Economics,undefined
[7] Cornell University,undefined
[8] Ithaca,undefined
[9] NY607255-2818,undefined
[10] USA (e-mail: ard23@cornell.edu),undefined
[11] CREPP,undefined
[12] Université de Liège,undefined
[13] CORE and Delta,undefined
[14] 7 Bvd du Rectorat,undefined
[15] 4000 Liège,undefined
[16] Belgium (+32-43663106,undefined
[17] e-mail: p.pestieau@ulg.ac.be),undefined