Lalaina Rakotonindrainy Paris School of Economics, Université Paris 1 Panthéon-Sorbonne   106 boulevard de l'Hopital Paris, 75013 France   Lalaina.Rakotonindrainy@malix.univ-paris1.fr             JEL Areas: D5 : General Equilibrium and Disequilibrium: General C6 : Mathematical Methods and Programming: General