Existence of financial equilibria with restricted participation

We consider a two-date model of a financial exchange economy with finitely many agents having nonordered preferences and portfolio constraints. There is a market for physical commodities at any state today or tomorrow and financial transfers across time and across states are allowed by means of finitely many nominal assets or numéraire assets. We prove a general existence result of equilibria for such a financial exchange economy in which portfolios are defined by linear constraints, extending the framework of linear equality constraints by Balasko et al. (1990), and the existence results in the unconstrained case by Cass (1984, 2006), Werner (1985), Duffie (1987), and Geanakoplos and Polemarchakis (1986). Our main result is a consequence of an auxiliary result, also of interest for itself, in which agents’ portfolio constraints are defined by general closed convex sets and the financial structure is assumed to satisfy a “nonredundancy-type” assumption, weaker than the ones in Radner (1972) and Siconolfi (1989).     

Self-enforcing international environmental agreements with a stock pollutant

In this paper the stability of an International Environmental Agreement (IEA) among N identical countries that emit a pollutant are studied using a two-stage game. In the first stage each country decides noncooperatively whether or not to join an IEA, and in the second stage signatories jointly against nonsignatories determine their emissions in a dynamic setting defined in continuous time. A numerical simulation shows that a bilateral coalition is the unique self-enforcing IEA independently of the gains coming from cooperation and the kind of strategies played by the agents (open-loop or feedback strategies). We have also studied the effects of a minimum participation clause finding that for this case a self-enforcing IEA just consists of the number of countries established in the clause.JEL Classification: C73, D62, Q28 Corresponding author : Santiago J. RubioThis paper is based on chapter four of Begoña Casinos Ph. Dissertation. Financial support from the Instituto Valenciano de Investigaciones Económicas, the Ministerio de Ciencia y Tecnología under grant BEC2000-1432 and Fundación BBVAis gratefully acknowledged. We also appreciate the helpful comments of three anonymous referees, whose suggestions improved the paper. Regarding any remaining inadequacies, the usual caveat applies.     

Selection dynamics and adaptive behavior without much information

This paper uses the experimental method to investigate behavior in a coordination game when the information available to subjects is limited to their feasible choices and their experienced payoffs. In the experiment subjects converge to an absorbing state at rates that are orders of magnitude faster than reinforcement learning algorithms, but slower than under complete information. This state is very close to a mutual best response outcome. All cohorts converged to the market statistic predicted by the interior equilibrium regardless of the information conditions or the stability conditions. Eric Battalio programmed the graphical user interface. The National Science Foundation and Texas Advanced Research Program provided financial support. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation or the Texas Advanced Research Program.     

Strategic behavior in financial markets

We describe a financial market as a noncooperative game in strategic form. Agents may borrow or deposit money at a central bank and use the cash available to them in order to purchase a commodity for immediate consumption. They derive positive utility from consumption and from having cash reserves at the end of the day, whereas being bankrupt entails negative utility. The bank fixes interest rates. The existence of Nash equilibria (both mixed and pure) of the ensuing game is proved under various assumptions. In particular, no agent is bankrupt at equilibrium. Asymptotic behavior of replica markets is discussed, and it is shown that given appropriate assumptions, the difference between a strategic player and a price taker is negligible in a large economy.     

非政府投资建设项目参与人行为的博弈分析

在非政府投资建设项目中,涉及四方参与人——业主、承包商、监理方和政府,他们的行为必然对工程质量产生影响。本文以寻租理论和委托代理理论为基础,建立了四方博弈模型,并求解了博弈过程的混合策略纳什均衡。通过对博弈结果的分析,提出在项目质量管理过程中应当建立的制度安排。