Comparative Statics in Cournot Free Entry Equilibrium

In this paper we study the effects of a change in an exogenous variable (the fixed cost or a parameter in the demand function) on the output and the number of active firms in a Symmetric Cournot Equilibrium with Free Entry (SCEFE). The results obtained here are different from those obtained in the Cournot model with a given number of firms. In particular, an increase in demand might yield a decrease in the output of the industry.We also show that any observation on prices, profits and number of firms is compatible with the assumption that the market is in a SCEFE. If fixed costs can be observed, there is a loose relationship between the profit rate and the number of active firms. This result is used as a warning against the use of the profit rate as a measure of an anticompetitive position and against the Structure–Conduct– Performance paradigm.Publicad

Zeeman-type dragging in the Kerr--Newman and NUT spacetimes

In this communication we discuss two distinct Zeeman-type gravitomagnetic effects deserving attention since they can be easily characterized in their exact form, not via approximation procedures. Some observations are also made on gravitoelectric effects.Comment: 5 pages, a talk delivered at the 11th Marcel Grossmann Meeting (2006

A correction on Shiloach's algorithm for minimum linear arrangement of trees

More than 30 years ago, Shiloach published an algorithm to solve the minimum linear arrangement problem for undirected trees. Here we fix a small error in the original version of the algorithm and discuss its effect on subsequent literature. We also improve some aspects of the notation.Comment: A new introductory paragraph has been added; error solutions and notation improvements are discussed with more dept

Credible Equilibria in Games with Utility Changing during the Play

Publicado por Tilburg Center Economic Research 1992Whenever one deals with an interactive decision situation of long duration, one has to take into account that priorities of the participants may change during the conflicto In this paper we propose an extensiveform game model to handle such situations and suggest and study a solution concept, called credible equilibrium, which generalizes the concept of Nash equilibrium. We also discuss possible variants to this concept and applications of the model to other types of games

Platform Pricing Structure and Moral Hazard

We study pricing by a monopoly platform that matches buyers and sellers in an environment with cross-market externalities. Said platform has no private information, does not set the commodity's price and can only charge trading parties for the transaction. Our innovation consists in introducing moral hazard on the sellers' side and an equilibrium notion of platform reputation in an infinite horizon model. With linear fees the platform can mitigate, but not eliminate, the loss of reputation induced by moral hazard. If lump-sum fees (registration fees) can be levied, moral hazard can be overcome. The upfront payment determines the participation threshold of sellers and extracts them, while (lower) transactions fees provide incentives for good behavior. This breaks the equivalence of lump-sum payments and linear fees (Rochet and Tirole (2006)). We draw implications for the role of subsidies (Caillaud and Jullien (2003)).Platforms; Two-Sided Markets; Reputation; Moral Hazard