First Author:   Igor Evstigneev School of Economic Studies, University of Manchester igor.evstigneev@man.ac.uk   School of Economic Studies, University of Manchester, Oxford Road Manchester, M13 9PL, UK   44-161-2754275(Phone) 44-161-2754275(Fax) http://les1.man.ac.uk/ses/staff/evstigneev/ Second Author: Guillaume Carlier Department of Applied Mathematics, University of Bordeaux 1 Guillaume.Carlier@math.u-bordeaux.fr   MAB, Universite Bordeaux I, 351, cours de la liberation Bordeaux, F-33405, France   05 56 84 66 41(Phone) 05 56 84 69 55(Fax)