[1] Ecole Polytech Fed Lausanne, Coll Management Technol, CEMI, CH-1015 Lausanne, Switzerland
[2] Minist Educ Natl, DEPP C2, F-75732 Paris 15, France
[3] Univ Nancy, BETA, Nancy, France
[4] CNRS, F-75700 Paris, France
[5] Conseil Concurrence, Paris, France