Fixed point theorems via Nash Equilibria

In this note we show that the fixed points of a continuous function (or of an upper semi-continuous correspondence, with non-empty and convex values) can be attained as Nash Equilibria of a game with finitely many players.

General equilibrium existence with asset-backed securitization

We propose a specification of a general equilibrium model with securitization of collateral-backed promises and discuss the role of physical collateral to avoid, in equilibrium, pessimistic beliefs about the future rates of default. Promises are pooled in either pass-through securities or collateralized loans obligations (CLO), allowing the existence of different seniority lev- els among tranches in the same CLO. In case of default, borrowers may also suffer extra-economic penalties, which are internalized into a structure of non-ordered preferences. In this context, we prove the existence of an equilibrium in that investors are not over-pessimistic about the payments of derivatives. JEL Codes: D52, D91Asset Backed-Securitization, Extra-economic Default Penalties, Collateral, Non- ordered Preferences

On equilibrium existence with endogenous restricted financial participation

Allowing for durable commodities, we prove equilibrium existence in an abstract incomplete market economy with endogenous restricted financial participation without requiring financial survival assumptions. We apply our results to general financial structures including nominal, real and collateralized asset markets.Equilibrium, Incomplete markets, Endogenous restricted nancial participation

On equilibrium existence in infinite horizon economies

In sequential economies with finite or infinite-lived real assets in positive net supply, we introduce constraints on the amount of borrowing in terms of the market value of physical endowments. We show that, when utility functions are either unbounded and separable in states of nature or separable in commodities, these borrowing constraints not only preclude Ponzi schemes but also induce endogenous Radner bounds on short-sales. Therefore, we obtain existence of equilibrium. Moreover, equilibrium also exists when both assets are numerarie and utility functions are quasilinear in the commodity used as numerarie.Equilibrium, Infinite horizon incomplete markets, Infinite-lived real assets.

Equilibrium with limited-recourse collateralized loans

We address a general equilibrium model with limited-recourse collateralized loans. Borrowers are burden to constitute physical collateral guarantees, which are repossessed in case of default and delivered to the associated lenders. In addition, lenders may receive payments over collateral values, since debtor's wealth (physical and financial) can be garnished when commitments are not fully honored. The reimbursement of resources is proportional to the size of claims.Collateralized assets; Bankruptcy, Limited-recourse loans; Equilibrium existence.

On the existence of pure strategy equilibria in large generalized games with atomic players

We consider a game with a continuum of players where only a finite number of them are atomic. Objective functions and admissible strategies may depend on the actions chosen by atomic players and on aggregate information about the actions chosen by non-atomic players. Only atomic players are required to have convex sets of admissible strategies and quasi-concave objective functions. We prove the existence of a pure strategy Nash equilibria. Thus, we extend to large generalized games with atomic players the results of equilibrium existence for non-atomic games of Schemeidler (1973) and Rath (1992). We do not obtain a pure strategy equilibrium by purification of mixed strategy equilibria. Thus, we have a direct proof of both Balder (1999, Theorem 2.1) and Balder (2002, Theorem 2.2.1), for the case where non-atomic players have a common non-empty set of strategies and integrable bounded codification of action profiles. Our main result is readily applicable to many interesting problems in general equilibrium. As an application, we extend Aumann (1966) result on the existence of equilibrium with a continuum of traders to a standard general equilibrium model with incomplete asset markets.Generalized games; Non-convexities; Pure-strategy Nash equilibrium

Endogenous differential information in financial markets

We develop a two period general equilibrium model with incomplete financial markets and differential information. Making endogenous the traditional informational restriction on consumption, we allow agents to obtain information from physical and financial markets. Thus, the investment in financial promises and the trade of commodities in spot markets appear as natural channels to improve the information that an agent has about the realization of future states of nature.Incomplete Markets, Differential information, Enlightening equilibrium.

El problema de la interferencia ferro-vial : el peligro viaja en tren

Fil: Martínez, Juan Pablo. Grupo Ferrourbanística; Argentina.En el Área Metropolitana Buenos Aires, un millón y medio de pasajeros utilizan el ferrocarril todos los días\nhábiles. Hay 650 pasos a nivel para vehículos (y peatones) y 340 pasos habilitados sólo para peatones.\nOcurren en los cruces unos 700 siniestros cada año, con alrededor de 350 muertos. Los accidentes\ncausan además severas alteraciones del servicio, originando airadas protestas de los usuarios. De esto\nse desprende la importancia de dar solución al problema de la interferencia entre los trenes y el tránsito.\nAquí se analizan las diferentes propuestas para lograrlo