Financial support from the following institutions, in addition to the personal contributions of the 200 parti- cipants, made the conference an enjoyable event - Universite d' Aix-Narseille III - Centre National de la Recherche Scientifique - City of Aix-en-Provence - Faculte d'Economie Appliquee - G.R.A.S.C.E. Association Fran~aise de Science economique - Air France - Chambre de Commerce et d'Industrie de Marseille - Chambre Regionale de Commerce et d'Industrie (Provence - Alpes - Cote d'Azur - Corse) - Compagnie Fran~aise des Petroles - Conseil General des Bouches-du-Rhone - Conseil Regional (Provence - Alpes - Cote d'Azur) - Electricite de France - Societe Lyonnaise de Banque - Societe Nationale des Chemins de Fer Fran~ais - Union des Assurances de Paris. Both before and during the conference, Hs. Daniele Durieu, Martine Harciano, Magali Orillard and Catherine pivot managed to avoid an always imminent chaos. P. Batteau, C. Jameux, J.L. Le Hoigne and J. de Montgolfier helped intensively in the organizing committee. The preparation of the manuscript owes much to Daniele Durieu and Isabelle ~1ichelot. J .A. Bartoli was most helpful in com~uterizing the preparation of the general index. He also benefited in this last respect of the help of our students I. Bouchet, R. Bout, P. de Cibeins, S. Delaye, C. Mallie, C. Martin, J-F. Morhain, J-C. Picton, N. Vock, all at the Faculte d'Economie Appliquee in Aix-en-Provence.