First Author:   Samuel Maveyraud GREThA samuel.maveyraud@u-bordeaux4.fr   Avenue Léon Duguit, Avenue Léon Duguit PESSAC, 33608, FRANCE   + 33 5 56 84 85 87(Phone) + 33 5 56 84 85 87(Fax) http://beagle.u-bordeaux4.fr/gretha-new/-Samuel-MAVEYRAUD-English-Version-.html Second Author: Yves Jegourel LAREFI, BEM Bordeaux Management School yves.jegourel@u-bordeaux4.fr   University of Montesquieu-Bordeaux IV, Avenue Léon Duguit PESSAC, 33608, FRANCE   +33 5 56 84 29 81(Phone) +33 5 56 84 85 34(Fax) http://lare-efi.u-bordeaux4.fr/Homepage/Jegourel/jegourel.htm