Jean-francois Laslier Ecole Polytechnique   Ecole Polytechnique Departement d'Economie Palaiseau, 91128 France   Jean-Francois.Laslier@polytechnique.edu   https://sites.google.com/site/jflaslierhomepage/           JEL Areas: D7 : Analysis of Collective Decision-Making: General C7 : Game Theory and Bargaining Theory:General