Sebastián Cea Echenique Department of Economics, University of Chile   s/n Rue de la ferme d'arny C/o Ulmer Domaine d'Arny Bruyères-le-chatel, 91680 France   seba.cea.echenique@gmail.com             JEL Areas: D5 : General Equilibrium and Disequilibrium: General C6 : Mathematical Methods and Programming: General