Welfare losses under cournot competition

We find that in a market for a homogeneous good where firms are identical, compete in quantities and produce with constant returns, the percentage of wel-fare losses (PWL) is small with as few as five competitors for a class of demand functions which includes linear and isoelastic cases. However with fixed costs and asymmetric firms PWL can be large. We provide exact formulae of PWL and robust constructions of markets were PWL is close to one in these two cases. We show that the market structure that maximizes PWL is either monopoly or dominant firm, depending on demand. Finally we prove that PWL is minimized when all firms are identical, a clear indication that the assumption of identical firms biases the estimation of PWL downwards.

TRADE AND GROWTH: A SIMPLE MODEL WITH NOT-SO-SIMPLE IMPLICATIONS

We present a simple dynamic model of international trade and growth. Our equations linking exogenous and endogenous variables do not resemble those estimated by the empirical literature: Ours are not linear, despite the fact that our model is linear, they do not include variables used in this literature and include variables that have never been used in this literature.

FORMS OF GOVERNANCE AND THE SIZE OF RENT-SEEKING

In this paper we present a model of an organization where agents can choose between productive and rent-seeking activities. We consider two governance institutions, single ownership and corporate governance or parliament rule. Applications include models of internal organization of a firm, of a kingdom ruled either by an absolute monarch or by the parliament, and location where agents can locate either in the court and become rent-seekers, or in an industrial city and become entrepreneurs. Our main goal is to study the size of rent-seeking activities under the two governance regimes. Under single ownership, rent-seeking reflects the taste of the owner for such activities and the possibilities of extracting rents from productive agents (who finance rent-seeking). The main conclusion of the paper is that, under corporate governance, the size of the rent-seeking sector may be larger than under single ownership despite the fact that in the former nobody has an intrinsic taste for rent-seeking activities.

Computing welfare losses from data under imperfect competition with heterogeneous goods

We study the percentage of welfare losses (PWL) yielded by imperfect competition under product differentiation. When demand is linear, if prices, outputs, costs and the number of firms can be observed, PWL is arbitrary in both Cournot and Bertrand equilibria. If in addition, the elasticity of demand (resp. cross elasticity of demand) is known, we can calculate PWL in Cournot (resp. Bertrand) equilibrium. When demand is isoelastic and there are many firms, PWL can be computed from prices, outputs, costs and the number of .rms. In all these cases we find that price-marginal cost margins and demand elasticities may influence PWL in a counterintuitive way. We also provide conditions under which PWL increases or decreases with concentration.Welfare losses, Product differentiation, Cournot equilibrium, Bertrand equilibrium

IMPLEMENTATION WITH STATE DEPENDENT FEASIBLE SETS AND PREFERENCES: A RENEGOTIATION APPROACH

In this paper we present a model of implementation based on the idea that agents renegotiate unfeasible allocations. We characterize the maximal set of Social Choice Correspondences that can be implemented in Nash Equilibrium with a class of renegotiation functions that do not reward agents for unfeasibilities. This result is used to study the possibility of implementing the Walrasian Correspondence in exchange economies and several axiomatic solutions to problems of bargaining and bankruptcy.

Peace agreements without commitment

In this paper we present a model of war between two rational and completely informed players. We show that in the absence of binding agreements war can be avoided in many cases by one player transferring money to the other player. In most cases, the "rich" country transfers part of her money to the "poor" country. Only when the military proficiency of the "rich" country is sufficiently great, it could be that the "poor" country can stop the war by transfering part of its resources to the "rich" country.

Cooperative production and efficiency

We characterize the sharing rule for which a contribution mechanism achieves efficiency in a cooperative production setting when agents are heterogeneous. The sharing rule bears no resemblance to those considered by the previous literature. We also show for a large class of sharing rules that if Nash equilibrium yields efficient allocations, the production function displays constant returns to scale, a case in which cooperation in production is useless.

TECHNOLOGY TRANSFER IN OLIGOPOLISTIC MARKETS WITH HETEROGENEOUS GOODS

In this paper we study technology transfer (TT) in a duopoly model with heterogeneous goods under quantity and price competition. We prove that some but not all the properties of TT under homogeneous goods are preserved in our framework.