José Manuel Jiménez-Gómez Universitat Rovira i Virgili   Av. Universitat, 1 Universitat Rovira i Virgili Reus, Tarragona 43204 Spain   josemanuel.jimenez@urv.cat             JEL Areas: C7 : Game Theory and Bargaining Theory:General D7 : Analysis of Collective Decision-Making: General