Genetic team composition and level of selection in the evolution of cooperation

In cooperative multiagent systems, agents interac to solve tasks. Global dynamics of multiagent teams result from local agent interactions, and are complex and difficult to predict. Evolutionary computation has proven a promising approach to the design of such teams. The majority of current studies use teams composed of agents with identical control rules ("geneti- cally homogeneous teams") and select behavior at the team level ("team-level selection"). Here we extend current approaches to include four combinations of genetic team composition and level of selection. We compare the performance of genetically homo- geneous teams evolved with individual-level selection, genetically homogeneous teams evolved with team-level selection, genetically heterogeneous teams evolved with individual-level selection, and genetically heterogeneous teams evolved with team-level selection. We use a simulated foraging task to show that the optimal combination depends on the amount of cooperation required by the task. Accordingly, we distinguish between three types of cooperative tasks and suggest guidelines for the optimal choice of genetic team composition and level of selection

After the Ban: The Japanese Market for U.S. Beef, April 2007

In the months following the reopening of the Japanese market to imports of U.S. beef on July 26, 2006, Japanese importers were unable to procure adequate supplies. This paper discusses reasons for early supply shortages and some of the policy and trade issues that will affect demand for U.S. beef in the short to medium term. The paper also discusses current marketing efforts for domestic and imported beef, new marketing technologies, and general consumer trends. The information presented in this paper includes on-site observations and data from meetings with Japanese importers and retailers and industry experts during market research in Tokyo and Osaka in November 2006.

Attribution and reciprocity in a simulated labor market: An experimental investigation

While papers such as Akerlof and Yellen (1990) and Rabin (1993) argue that psychological considerations such as fairness and reciprocity are important in individual decision-making, there is little explicit empirical evidence of reciprocal altruism in economic environments. This paper tests whether attribution of volition in choosing a wage has a significant effect on subsequent costly effort provision. An experiment was conducted in which subjects are first randomly divided into groups of employers and employees. Wages were selected and employees asked to choose an effort level, where increased effort is costly to the employee, but highly beneficial to the employer. The wage-determination process was common knowledge and wages were chosen either by the employer or by an external process. There is evidence for both distributional concerns and reciprocal altruism. The slope of the effort/wage profile is clearly positive in all cases, but is significantly higher when wages are chosen by the employer, offering support for the hypothesis of reciprocity. There are implications for models of utility and a critique of some current models is presented.

Common law and civil law as pro-market adaptations

We argue that in the development of the Western legal system, cognitive departures are themain determinant of the optimal degree of judicial rule-making. Judicial discretion, seen here as the main distinguishing feature between both legal systems, is introduced in civil law jurisdictions to protect, rather than to limit, freedom of contract against potential judicial backlash. Such protection was unnecessary in common law countries, where free-market relations enjoyed safer judicial ground mainly due to their relatively gradual evolution, their reliance on practitioners as judges, and the earlier development of institutional checks and balances that supported private property rights. In our framework, differences in costs and benefits associated with self-interest and lack of information require a cognitive failure to be active.

Interbank market integration under asymmetric information

We argue that the main barrier to an integrated international interbankmarket is the existence of asymmetric information between differentcountries, which may prevail in spite of monetary integration or successfulcurrency pegging. In order to address this issue, we study the scope forinternational interbank market integration with unsecured lending whencross-country information is noisy. We find not only that an equilibriumwith integrated markets need not always exist, but also that when it does,the integrated equilibrium may coexist with one of interbank marketsegmentation. Therefore, market deregulation, per se, does not guaranteethe emergence of an integrated interbank market. The effect of a repo marketwhich, a priori, was supposed to improve efficiency happens to be morecomplex: it reduces interest rate spreads and improves upon the segmentationequilibrium, but\ it may destroy the unsecured integrated equilibrium, sincethe repo market will attract the best borrowers. The introduction of othertransnational institutional arrangements, such as multinational banking,correspondent banking and the existence of "too-big-to-fail" banks mayreduce cross country interest spreads and provide more insurance againstcountry wide liquidity shocks. Still, multinational banking, as theintroduction of repos, may threaten the integrated interbank marketequilibrium.

Market and institutional determinants in the regulation of conveyancers

Demand for law professionals in the conveyancing of property is decreasing because of market and institutional changes. On the market side, many transactions feature large, well-known parties and standardized transactions, which make professionals less effective or necessary for protecting the parties to private contracts. On the institutional side, public titling makes it possible to dispense with a broadening set of their former functions. Recording of deeds made professionals redundant as depositories of deeds and reduced demand for them to design title guarantees. Effective registration of rights increasingly substitutes professionals for detecting title conflicts with third parties and gathering their consent. Market changes undermine the information asymmetry rationale for regulating conveyancing, while institutional changes facilitate liberalizing not only conduct but also license regulations. These arguments are supported here by disentangling the logic of titling systems and presenting empirical evidence from the European and USA markets.

Toward a theory of labor market institutions

Standard economic analysis holds that labor market rigidities are harmfulfor job creation and typically increase unemployment. But many orthodoxreforms of the labor market have proved difficult to implement because ofpolitical opposition. For these reasons it is important to explain why weobserve such regulations. In this paper I outline a theory of how they may arise and why they fit together. This theory is fully developed in aforthcoming book (Saint-Paul (2000)), to which the reader is referred forfurther details.

Monetary policy with signal extraction from the bond market

Monetary policy is conducted in an environment of uncertainty. This paper sets upa model where the central bank uses real-time data from the bond market togetherwith standard macroeconomic indicators to estimate the current state of theeconomy more efficiently, while taking into account that its own actions influencewhat it observes. The timeliness of bond market data allows for quicker responsesof monetary policy to disturbances compared to the case when the central bankhas to rely solely on collected aggregate data. The information content of theterm structure creates a link between the bond market and the macroeconomythat is novel to the literature. To quantify the importance of the bond market asa source of information, the model is estimated on data for the United Statesand Australia using Bayesian methods. The empirical exercise suggests that thereis some information in the US term structure that helps the Federal Reserve toidentify shocks to the economy on a timely basis. Australian bond prices seemto be less informative than their US counterparts, perhaps because Australia is arelatively small and open economy.

Three essays in dynamic corporate finance

Summary Throughout my thesis, I elaborate on how real and financing frictions affect corporate decision making under uncertainty, and I explore how firms time their investment and financing decisions given such frictions. While the macroeconomics literature has focused on the impact of real frictions on investment decisions assuming all equity financed firms, the financial economics literature has mainly focused on the study of financing frictions. My thesis therefore assesses the join interaction of real and financing frictions in firms' dynamic investment and financing decisions. My work provides a rationale for the documented poor empirical performance of neoclassical investment models based on the joint effect of real and financing frictions on investment. A major observation relies in how the infrequency of corporate decisions may affect standard empirical tests. My thesis suggests that the book to market sorts commonly used in the empirical asset pricing literature have economic content, as they control for the lumpiness in firms' optimal investment policies. My work also elaborates on the effects of asymmetric information and strategic interaction on firms' investment and financing decisions. I study how firms time their decision to raise public equity when outside investors lack information about their future investment prospects. I derive areal-options model that predicts either cold or hot markets for new stock issues conditional on adverse selection, and I provide a rational approach to study jointly the market timing of corporate decisions and announcement effects in stock returns. My doctoral dissertation therefore contributes to our understanding of how under real and financing frictions may bias standard empirical tests, elaborates on how adverse selection may induce hot and cold markets in new issues' markets, and suggests how the underlying economic behaviour of firms may induce alternative patterns in stock prices.

Sex allocation and sex-dependent selection for body size in Trypoxylon rogenhoferi Kohl (Hymenoptera, Sphecidae)

Two populations of the wasp Trypoxylon rogenhoferi Kohl, 1884 from São Carlos and Luís Antônio, State of São Paulo, Brazil, were observed and sampled from May 1999 to February 2001 using trap-nests. This mass-provisioning wasp was used to test some aspects of optimal sex allocation theory. Both populations fit all the predictions of the models of Green and Brockmann and Grafen. Maternal provisions determined the size of each offspring, and females allocated well-stocked brood cells to daughters, the sex that benefits most being large. This strategy resulted in a difference in size between the sexes. In São Carlos, female weight at emergence was 1.18 times that of males, in Luís Antônio this value was 1.13. The brood cell volume was correlated with both wing length and weight at emergence in both sexes, and the chance that a given brood cell contained a male offspring decreased with increased brood cell volume. In T. rogenhoferi female body size was related to fitness. Larger females were able to collect more mass of spiders per day, the spiders they captured were heavier, and they provisioned more brood cells per day. They also produced larger daughters. For males, no relationship between body size and fitness was found, but the data were scarce. Since the patterns of provisioning were variable among different females in both study sites, it is possible that the females not follow a unique strategy for sex allocation. The sex ratio and/or investment ratio in the São Carlos population was female-biased and in Luís Antônio, male-biased. In spite of the influence of trap-nests diameters on male production in Luís Antônio, there is some evidence that in São Carlos population the local availability of prey and/or lower rate of parasitism may be major forces in determining the observed sex ratio, but further studies are necessary to verify such hypothesis.

Selective hiring and welfare analysis in labor market models

Firms select not only how many, but also which workers to hire. Yet, in standardsearch models of the labor market, all workers have the same probability of being hired.We argue that selective hiring crucially affects welfare analysis. Our model is isomorphicto a search model under random hiring but allows for selective hiring. With selectivehiring, the positive predictions of the model change very little, but the welfare costsof unemployment are much larger because unemployment risk is distributed unequallyacross workers. As a result, optimal unemployment insurance may be higher and welfareis lower if hiring is selective.

Determining underlying macroeconomic fundamentals during emerging market crises: Are conditions as bad as they seem?

Emerging market crises are characterized by large swings in both macroeconomic fundamentalsand asset prices. The economic significance of observed movements in macroeconomicvariables is obscured by the brief and extreme nature of crises. In this paper we propose to study the macroeconomic consequences of crises by studying the behavior of effective fundamentals, constructed by studying the relative movements of stock prices during crises. We find that these effective fundamentals provide a different picture than that implied by observed fundamentals. First, asset prices often reflect expectations of improvement in fundamentals after the initial devaluations; specifically, effective depreciations are positive but not as large as the observed ones. Second, crises vary in their effect on credit market conditions, with investors expecting tightening of credit in some cases (Mexico 1994, Philippines 1997), but loosening of credit in others (Sweden 1992, Korea 1997, Brazil 1999).