Christian Bidard is Professor of Economics at the University of Paris X-Nanterre. He is the editor or the author of several books on Sraffa's theory: Prix, Reproduction, Rarete (1991, La Rente (1987), La Production Jointe (1984), and its relationship with Keynesian theory. He is the author of over seventy papers in economic journals and books largely devoted to the theory of long-term competitive prices.