Improving the Milk Supply Chain in Developing Countries: Analysis,Insights, and Recommendations

Quality issues in milk—arising primarily from deliberate adulteration by producers—have been reported in several developing countries. In the milk supply chain, a station buys raw milk from a number of producers, mixes the milk and sells it to a firm (that then sells the processed milk to end consumers). We study a non‐cooperative game between a station and a population of producers. Apart from penalties on proven low‐quality producers, two types of incentives are analyzed: confessor rewards for low‐quality producers who confess and quality rewards for producers of high‐quality milk. Contrary to our expectations, whereas (small) confessor rewards can help increase both the quality of milk and the station's profit, quality rewards can be detrimental. We examine two structures based on the ordering of individual and mixed testing of milk: pre‐mixed individual testing (first test a fraction of producers individually and then [possibly] perform a mixed test on the remaining producers) and post‐mixed individual testing (first test the mixed milk from all producers and then test a fraction of producers individually). Whereas pre‐mixed individual testing can be socially harmful, a combination of post‐mixed individual testing and other incentives achieves a desirable outcome: all producers supply high‐quality milk with only one mixed test and no further testing by the station.     

Two-Speed Evolution of Strategies and Preferences In Symmetric Games

Agents in a large population are randomly matched to play a certain game, payoffs in which represent fitness. Agents may have preferences that are different from fitness. They learn strategies according to their preferences, and evolution changes the preference distribution in the population according to fitness. When agents know the preferences of the opponent in a match, only efficient symmetric strategy profiles of the fitness game can be stable. When agents do not know the preferences of the opponent, only Nash equilibria of the fitness game can be stable. For 2 × 2 symmetric games I characterize preferences that are stable.Jel Codes: C72, A13     

A theory of forward induction in finitely repeated games

A forward induction solution for finitely repeated games with complete information is developed. This notion is motivated in terms of its implications on the way deviations affect the opponents' expectations about the future behavior of the deviating player. We argue that the inability of the notion of perfect equilibrium to take account of forward induction is a key factor responsible for a number of difficulties encountered in the use of perfect equilibria in repeated games. It is then shown that the solution proposed in this paper remedies some of these problems in the study of three important classes of repeated games: (i) finitely repeated coordination games; (ii) repeated games where one long-term player plays a sequence of short-term players; (iii) repeated battle of the sexes games.     

The Evolution of Cooperative Strategies for Asymmetric Social Interactions

How can cooperation be achieved between self-interested individuals in commonly-occurring asymmetric interactions where agents have different positions? Should agents use the same strategies that are appropriate for symmetric social situations? We explore these questions through the asymmetric interaction captured in the indefinitely repeated investment game (IG). In every period of this game, the first player decides how much of an endowment he wants to invest, then this amount is tripled and passed to the second player, who finally decides how much of the tripled investment she wants to return to the first player. The results of three evolutionary studies demonstrate that the best-performing strategies for this asymmetric game differ from those for a similar but symmetric game, the indefinitely repeated Prisoner’s dilemma game. The strategies that enable cooperation for the asymmetric IG react more sensitively to exploitation, meaning that cooperation can more easily break down. Furthermore, once cooperation has stopped, it is much more difficult to reestablish than in symmetric situations. Based on these results, the presence of asymmetry in an interaction appears to be an important factor affecting adaptive behavior in these common social situations.     

The Lovász Extension of Market Games

The multilinear extension of a cooperative game was introduced by Owen in 1972. In this contribution we study the Lovász extension for cooperative games by using the marginal worth vectors and the dividends. First, we prove a formula for the marginal worth vectors with respect to compatible orderings. Next, we consider the direct market generated by a game. This model of utility function, proposed by Shapley and Shubik in 1969, is the concave biconjugate extension of the game. Then we obtain the following characterization: The utility function of a market game is the Lovász extension of the game if and only if the market game is supermodular. Finally, we present some preliminary problems about the relationship between cooperative games and combinatorial optimization.     

Complex Questionnaires

We study a principal–agent model in which the agent is boundedly rational in his ability to understand the principal's decision rule. The principal wishes to elicit an agent's true profile so as to determine whether or not to grant him a certain request. The principal designs a questionnaire and commits himself to accepting certain responses. In designing such a questionnaire, the principal takes into account the bounded rationality of the agent and wishes to reduce the success probability of a dishonest agent who is trying to game the system. It is shown that the principal can construct a sufficiently complex questionnaire that will allow him to respond optimally to agents who tell the truth and at the same time to almost eliminate the probability that a dishonest agent will succeed in cheating.     

魏晋清谈：语言游戏——以伽达默尔的游戏概念为视角对魏晋清谈的分析

以伽达默尔的游戏概念观之,魏晋清谈是一种充满艺术气质的严肃的学术社交活动,是一种语言游戏,魏晋士人在这种基于"问-答"结构的语言游戏中探讨人生、社会、宇宙的哲理,追求不同于儒家价值和真理的另一种价值和真理.     

Therapeutic Applications of Online Gaming

ABSTRACT

This article discusses online gaming in the twenty-first century, describes online gaming, considers negative and positive aspects of gaming, and proposes several possible research, practice, and educational strategies for subsequent development of this genre into a useful tool for human service interventions. Positive characteristics of online gaming environments such as high levels of social interaction and the potential for transformative experiences strongly suggest that many clients will be utilizing such environments. In addition, practitioners must not only learn to assess client use of gaming but also develop the necessary knowledge and skills to utilize online games as therapeutic tools.     

区域游戏中幼儿学习行为的图式论解析

图式理论研究不仅为幼儿园区域游戏的开展提供理论指导，同时也提供了可操作的技术支持，在帮助教师更好地理解 幼儿学习特点与学习品质的同时也提升教师对区域游戏活动因区而异、精准指导的水平。本研究采用观察法、案例分析法和 文本解析法对区域游戏中幼儿学习行为的特点进行了研究，在重点梳理与分析覆盖—容纳、动态旋转、动态垂直、动态来回四 种图式类型行为特点的基础上，对幼儿的学习特点进行解读，同时发现不同类型图式存在着典型性、稳定性、发展性和一致性 等共性特征，并在此基础上提出了相应的研究启示。     

Collusion With Persistent Cost Shocks

We consider a dynamic Bertrand game in which prices are publicly observed and each firm receives a privately observed cost shock in each period. Although cost shocks are independent across firms, within a firm costs follow a first‐order Markov process. We analyze the set of collusive equilibria available to firms, emphasizing the best collusive scheme for the firms at the start of the game. In general, there is a trade‐off between productive efficiency, whereby the low‐cost firm serves the market in a given period, and high prices. We show that when costs are perfectly correlated over time within a firm, if the distribution of costs is log‐concave and firms are sufficiently patient, then the optimal collusive scheme entails price rigidity: firms set the same price and share the market equally, regardless of their respective costs. When serial correlation of costs is imperfect, partial productive efficiency is optimal. For the case of two cost types, first‐best collusion is possible if the firms are patient relative to the persistence of cost shocks, but not otherwise. We present numerical examples of first‐best collusive schemes.