Damien GAUMONT - Professor (université Paris 2 Panthéon-Assas)
Julian REVALSKI - Professor (Académie des Sciences de Sofia)
Bertrand WIGNIOLLE - Professor (université Paris I)
Joël BLOT - Professor (université Paris 1)
Bertrand CRETTEZ - Professor (université Paris 2 Panthéon-Assas)
This thesis constructs a theoretical model that renews the traditional approach of the market equilibrium. By introducing into the neoclassical paradigm the principle of preference for quantity, it optimally generates inventories within a competitive market. The results are very important since they explain both the emergence of unsold goods and the existence of economic cycles. In addition, it studies the optimal behavior of a monopolist whose the market power depends not only on the quantity of displayed goods but also that of goods that the main consumer is willing to buy. Contrary to the traditional assumption that the monopolist chooses price or quantity that maximizes its profit, through a generalized Lerner index (GLI) it attracts customers' demand by both the price and the quantity of displayed goods. Whatever the market structure, the phenomenon of inventory accumulation appears in the economy. Furthermore, it has the advantage of explicitly explaining impulse purchases untreated by economics. To check the robustness of the results, the theoretical model is fitted to U.S. data. Due to its nonlinearity, the Gauss-Newton method is appropriate to highlight the impact of consumers' preference for quantity on production and accumulation of goods and consequently GDP forecast. Finally, this thesis builds a two-country overlapping generations (OLG) model which extends the dynamic OLG equilibrium to a frictionless dynamic OLG gamma-equilibrium. Based on the cash-in-advance constraint, it highlights the conditions of over-accumulation of capital and welfare implications of capital mobility in a context of accumulation of stock of unsold goods.