经济学顶刊Journal of Economic Theory 2023年第1期
Journal of Economic Theory 2023年第1期
——更多动态，请持续关注gzh：理想主义的百年孤独
1.Equilibrium social activity during an epidemic
流行病期间的均衡社会活动
David McAdams, Yangbo Song, Dihan Zou
During an infectious-disease epidemic, people make choices that impact transmission, trading off the risk of infection with the social-economic benefits of activity. We investigate how the qualitative features of an epidemic's Nash-equilibrium trajectory depend on the nature of the economic benefits that people get from activity. If economic benefits do not depend on how many others are active, as usually modeled, then there is a unique equilibrium trajectory, the epidemic eventually reaches a steady state, and agents born into the steady state have zero expected lifetime welfare. On the other hand, if the benefit of activity increases as others are more active (“social benefits”) and the disease is sufficiently severe, then there are always multiple equilibrium trajectories, including some that never settle into a steady state and that welfare dominate any given steady-state equilibrium. Within this framework, we analyze the equilibrium impact of a policy that modestly reduces the transmission rate. Such a policy has no long-run effect on society-wide welfare absent social benefits, but can raise long-run welfare if there are social benefits and the epidemic never settles into a steady state.
在传染病流行期间，人们会做出影响传播的选择，权衡感染风险与活动的社会经济效益。我们研究了流行病纳什均衡轨迹的定性特征如何依赖于人们从活动中获得的经济利益的性质。如果经济利益不依赖于其他有多少人活跃，就像通常建模的那样，那么就有一个独特的均衡轨迹，流行病最终达到一个稳定状态，而出生在稳定状态中的代理人的预期终身福利为零。另一方面，如果随着其他人更积极活动(“社会福利”)的增加，并且疾病足够严重，那么总是会有多个平衡轨迹，包括一些永远不会稳定到稳定状态，福利主导任何给定的稳定状态平衡。在这个框架内，我们分析了适度降低传导率的政策的均衡影响。在没有社会福利的情况下，这样的政策对全社会福利没有长期影响，但在有社会福利且疫情从未稳定下来的情况下，可以提高长期福利。
2.Pledge-and-review bargaining
承诺和审查的讨价还价
Bård Harstad
This paper presents a novel dynamic bargaining game where every party is proposing only its own contribution, before all pledges must be unanimously approved. I show that, with uncertain tolerance for delay, each equilibrium pledge maximizes an asymmetric Nash product. The weights on others' payoffs increase in the uncertainty, but decrease in the correlation of the shocks. The weights vary pledge to pledge, and this implies that the outcome is generically inefficient. The Nash demand game and its mapping to the Nash bargaining solution follow as a limiting case. The model sheds light on the Paris climate change agreement, but it also applies to negotiations between policymakers or business partners that have differentiated responsibilities or expertise.
本文提出了一个新颖的动态谈判博弈，在所有承诺必须一致通过之前，各方只提出自己的贡献。我证明，在延迟容忍不确定的情况下，每个均衡承诺最大化了一个非对称纳什乘积。在不确定性中，对他人收益的权重增加，但冲击的相关性降低。各个质押的权重不同，这意味着结果通常是低效的。纳什需求博弈及其与纳什谈判解的映射是一个极限情形。该模式揭示了巴黎气候变化协议，但它也适用于负有不同责任或专长的决策者或商业伙伴之间的谈判。
3.Homophily and influence
同质性和影响力
Arnold Polanski, Fernando Vega-Redondo
We study how learning and influence co-evolve in a social network by extending the classical model of DeGroot (1974) in two fundamental ways:
(a) opinions are multidimensional and the learning time-span is arbitrary;
(b) the effective social network is endogenously shaped by opinion-based homophily.
Our analysis starts by establishing the existence of an equilibrium where, following (a)-(b), the learning outcome and the social network are jointly determined. This is followed by its characterization in some simple contexts. Next, we show that, at equilibrium, the strength of the link between any two agents is always given by its “support” – roughly, the amount of third-party (indirect) influence impinging on both agents. This result leads to the key insight that distinct groups may fail to integrate if their (possibly many) cross-group links lack sufficient support. Building on this, we identify sets of conditions for which social fragmentation is robust (i.e. dynamically stable) or even the unique equilibrium.
本文从两个方面扩展了DeGroot(1974)的经典模型，研究了学习和影响力如何在社会网络中共同演化:(1)观点是多维的，学习的时间跨度是任意的;(b)有效社会网络内生性地受到基于意见的同质性塑造。我们的分析首先建立了一个均衡的存在，在(a)-(b)之后，学习结果和社会网络是共同确定的。接下来是在一些简单的上下文中对其进行表征。接下来，我们表明，在均衡状态下，任何两个代理之间的联系强度总是由其“支持”给出——大致来说，就是影响两个代理的第三方(间接)影响的数量。这一结果导致了关键的见解，即如果不同的群体(可能很多)的跨群体联系缺乏足够的支持，那么他们可能无法整合。在此基础上，我们确定了社会分裂是稳健(即动态稳定)甚至是独特均衡的一系列条件。
4.Comment on “A theoretical foundation of ambiguity measurement”
“模糊度测量的理论基础”述评
Ruonan Fu, Bertrand Melenberg, Nikolaus Schweizer
In this paper, we study asymptotic expansions for distorted probabilities under ambiguity, revisiting the framework and analysis of Izhakian (2020b). We argue that the first order terms in these expansions need to be corrected and provide alternatives. We also revisit later results in this paper on the separation of ambiguity and ambiguity attitudes. We argue that a crucial lemma is flawed implying that Izhakian's ambiguity measure ℧2 is not an equivalent way of representing the preferences it is supposed to represent.
本文研究了模糊条件下失真概率的渐近展开式，回顾了Izhakian (2020b)的框架和分析。我们认为，这些展开中的一阶项需要修正，并提供替代方案。我们还回顾了本文稍后关于歧义和歧义态度分离的结果。我们认为一个关键引理是有缺陷的，这意味着伊扎克ian的模糊性度量℧2不是表示它应该表示的偏好的等效方式。
5.On perfect pairwise stable networks
在完美成对稳定网络上
Philippe Bich, Mariya Teteryatnikova
We extend standard tools from equilibrium refinement theory in non-cooperative games to a cooperative framework of network formation. First, we introduce the new concept of perfect pairwise stability. It transposes the idea of “trembling hand” perfection to network formation theory and strictly refines the pairwise stability concept of Jackson and Wolinsky (1996). Second, we study basic properties of perfect pairwise stability: existence, admissibility and perturbation. We further show that our concept is distinct from the concept of strongly stable networks introduced by Jackson and Van den Nouweland (2005), and perfect Nash equilibria of the Myerson network formation game studied by Calvó-Armengol and İlkılıç (2009). Finally, we apply perfect pairwise stability to sequential network formation and prove that it enables a refinement of sequential pairwise stability, a natural analogue of subgame perfection in a setting with cooperative, pairwise link formation.
本文将标准工具从非合作博弈的均衡细化理论扩展到合作网络形成框架。首先，我们引入了完全两两稳定的新概念。它将“颤抖的手”完美的概念转换为网络形成理论，严格提炼了Jackson and Wolinsky(1996)的两两稳定概念。其次，我们研究了完全两两稳定的基本性质:存在性、容许性和摄动性。我们进一步表明，我们的概念不同于Jackson和Van den Nouweland(2005)提出的强稳定网络的概念，也不同于Calvó-Armengol和İlkılıç(2009)研究的Myerson网络形成博弈的完美纳什均衡。最后，我们将完美成对稳定性应用于顺序网络形成，并证明了它可以改进顺序成对稳定性，这是在合作成对链接形成的环境中子博弈完美的自然模拟。
6.Randomization is optimal in the robust principal-agent problem
在稳健的委托代理问题中，随机化是最优的
Ashwin Kambhampati
A principal contracts with an agent, who takes a hidden action. The principal does not know all of the actions the agent can take and evaluates her payoff from any contract according to its worst-case performance. Carroll (2015) showed that there exists a linear contract that is optimal within the class of deterministic contracts. This paper shows that, whenever there is an optimal linear contract with non-zero slope, the principal can strictly increase her payoff by randomizing over deterministic, linear contracts. Hence, if the principal believes that randomization can alleviate her ambiguity aversion, then restricting attention to the study of deterministic contracts is with loss of generality.
委托人与代理人签订合同，代理人采取隐蔽行动。委托人并不知道代理人可以采取的所有行动，并根据最坏情况下的表现来评估她从任何合同中获得的回报。Carroll(2015)的研究表明，在一类确定性契约中存在一个最优的线性契约。本文表明，当存在斜率为非零的最优线性契约时，委托人可以通过对确定性线性契约的随机化严格增加其收益。因此，如果委托人认为随机化可以减轻她对模糊性的厌恶，那么将注意力限制在确定性契约的研究上就失去了一般性。
7.Information design through scarcity and social learning
通过稀缺和社会学习进行信息设计
Alexei Parakhonyak, Nick Vikander
We show that a firm may benefit from strategically creating scarcity for its product, in order to trigger herding behaviour from consumers in situations where such behaviour is otherwise unlikely. We consider a setting with social learning, where consumers observe sales from previous cohorts and update beliefs about product quality before making their purchase. Imposing a capacity constraint directly limits sales but also makes information coarser for consumers, who react favourably to a sell-out because they infer only that demand must exceed capacity. Consumer learning is then limited even with large cohorts and unbounded private signals, because the firm acts strategically to influence the consumers' learning environment. Our results suggest that in suitable environments capacity constraints can serve as a useful tool to implement optimal information design in practice: if private signals are not too precise and capacity can be changed over time, then in large markets the firm's optimal choice of capacity delivers the same expected sales as the Bayesian persuasion solution.
我们的研究表明，企业可以从战略性地为其产品创造稀缺性中获益，以在其他情况下不太可能引发消费者的羊群行为。我们考虑一个具有社会学习的环境，在这个环境中，消费者观察以前群体的销售情况，并在购买之前更新对产品质量的信念。施加产能限制会直接限制销售，但也会让消费者的信息更加粗糙，他们对售罄的情况反应积极，因为他们只是推断需求必须超过产能。因此，即使在大群体和无界私人信号的情况下，消费者的学习也受到限制，因为企业会策略性地影响消费者的学习环境。我们的结果表明，在合适的环境中，容量限制可以作为实践中实施最优信息设计的有用工具:如果私人信号不太精确，容量可以随着时间的推移而改变，那么在大型市场中，企业对容量的最优选择可以提供与贝叶斯说服解决方案相同的预期销售。
8.Symmetry in n-player games
N个参与者的博弈中的对称性
Asaf Plan
This paper regards symmetry in games with more than two players. It is often said that a two-player game is symmetric if it looks the same to both players. However, there are n-player games, such as Salop's circle model, that seem intuitively to look the same to all players, but do not meet the common definition of a symmetric n-player game. This paper proposes a more general symmetry condition that is satisfied by such models. Previous authors have established that games which are symmetric in the common sense have a number of useful properties relating to equilibrium characterization and comparative statics. With few exceptions, those properties continue to hold in the richer class of games that meet the symmetry condition proposed here.
本文考虑了两个以上参与人博弈的对称性。我们常说，如果一个双人游戏在两个玩家看来都是一样的，那么它就是对称的。然而，也有一些n人游戏，如Salop的circle模型，在所有玩家看来似乎都是一样的，但却不符合对称n人游戏的一般定义。本文提出了这类模型所满足的更一般的对称性条件。以前的作者已经确定，在常识上对称的博弈具有许多与平衡表征和比较静态学有关的有用性质。除了少数例外，这些性质在满足这里提出的对称条件的更丰富的博弈中仍然成立。
9.Loss aversion in strategy-proof school-choice mechanisms
策略型择校机制中的损失规避
Vincent Meisner, Jonas von Wangenheim
Evidence suggests that participants in strategy-proof matching mechanisms play dominated strategies. To explain the data, we introduce expectation-based loss aversion into a school-choice setting and characterize choice-acclimating personal equilibria. We find that non-truthful preference submissions can be strictly optimal if and only if they are top-rank monotone. In equilibrium, inefficiency or justified envy may arise in seemingly stable or efficient mechanisms. Specifically, students who are more loss averse or less confident than their peers obtain suboptimal allocations.
有证据表明，策略证明匹配机制的参与者使用主导策略。为了解释这些数据，我们将基于预期的损失厌恶引入学校选择设置，并描述选择适应个人平衡。我们发现，当且仅当非真实偏好提交是顶级单调时，非真实偏好提交是严格最优的。在平衡状态下，看似稳定或有效的机制可能会产生无效率或合理的嫉妒。具体而言，与同龄人相比，更不愿损失或更不自信的学生获得了次优分配。
10.Epidemics with behavior
行为的传染
Christoph Carnehl, Satoshi Fukuda, Nenad Kos
We study social distancing in an epidemiological model. Distancing reduces the individual's probability of getting infected but comes at a cost. Equilibrium distancing flattens the curve and decreases the final size of the epidemic. We examine the effects of distancing on the outset, the peak, and the final size of the epidemic. First, the prevalence increases beyond the initial value only if the transmission rate is in the intermediate region. Second, the peak of the epidemic is non-monotonic in the transmission rate. A reduction in the transmission rate can increase the peak. However, a decrease in the cost of distancing always flattens the curve. Third, both a reduction in the transmission rate as well as a reduction in the cost of distancing decrease the final size of the epidemic. Our results suggest that public policies that decrease the transmission rate can lead to unintended negative consequences in the short run but not in the long run. Therefore, it is important to distinguish between interventions that affect the transmission rate and interventions that affect contact rates.
我们在流行病学模型中研究社会距离。保持距离降低了个人被感染的可能性，但也付出了代价。均衡距离使曲线变平，最终减小了疫情规模。我们研究了距离对疫情开始、峰值和最终规模的影响。首先，只有当传播率在中间区域时，流行率才会超过初始值。二是疫情高峰期传播速率非单调性。降低传输速率可以提高峰值。然而，距离成本的降低总是会使曲线变平。第三，传播速度的降低以及保持距离成本的降低都降低了疫情的最终规模。我们的研究结果表明，降低传播率的公共政策可能会在短期内而不是在长期内导致意想不到的负面后果。因此，重要的是要区分影响传播率的干预措施和影响接触率的干预措施。
11.Communication with endogenous deception costs
内生欺骗的沟通成本
Ran Eilat, Zvika Neeman
We study how the suspicion that communicated information might be deceptive affects the nature of what can be communicated in a sender-receiver game. Sender is said to deceive Receiver if she sends a message that induces a belief that is different from the belief that should have been induced in the realized state. Deception is costly to Sender and the cost is endogenous: it is increasing in the distance between the induced belief and the belief that should have been induced. A message function that induces Sender to engage in deception is not credible and cannot be part of an equilibrium. We study credible communication with state-dependent and state-independent Sender's preferences. The cost of deception parametrizes the sender's ability to commit to her strategy. Through varying this cost, our model spans the range from cheap talk, or no commitment (Crawford and Sobel, 1982) to full commitment (Kamenica and Gentzkow, 2011).
我们研究的是，在发送者和接收者之间的游戏中，对传递信息可能具有欺骗性的怀疑如何影响传递信息的本质。如果发送者发送的信息诱导了一个信念，而这个信念与在已实现状态下应该诱导的信念不同，那么发送者就被认为欺骗了接收者。欺骗对发送者来说是昂贵的，而且这种成本是内生的:它在诱导的信念和本应诱导的信念之间的距离上增加。诱导发送者参与欺骗的信息功能是不可信的，不可能是平衡的一部分。我们研究了基于国家依赖和国家独立发送者偏好的可信沟通。欺骗的代价参数化了发送者执行策略的能力。通过改变这一成本，我们的模型涵盖了从廉价谈话或不承诺(Crawford and Sobel, 1982)到完全承诺(Kamenica and Gentzkow, 2011)的范围。
12.Decentralizability of efficient allocations with heterogeneous forecasts
具有异质性预测的有效分配的分散性
Shurojit Chatterji, Atsushi Kajii
Do price forecasts of rational economic agents need to coincide in intertemporal perfectly competitive complete markets in order for markets to allocate resources efficiently? To address this question, we define an efficient temporary equilibrium (ETE) within the framework of a two period economy. Although an ETE allocation is intertemporally efficient and is obtained by perfect competition, it can arise without the agents' forecasts being coordinated on a perfect foresight price. With time-separable utilities, we show that there is a one dimensional set of ETE allocations for generic endowments. Moreover, these efficient allocations can be supported by forecasts that disagree up to one degree of freedom. Thus, strong as efficiency and perfect competition may appear, they do not imply perfect foresight, but they do add explanatory power to temporary equilibrium, since they select a small subset out of the Pareto efficient allocations, which generally have higher dimension.
在跨期完全竞争市场中，理性经济主体的价格预测是否需要一致才能使市场有效配置资源?为了解决这个问题，我们在两期经济的框架下定义了一个有效的临时均衡(ETE)。虽然ETE配置是完全竞争下的跨期有效配置，但它可能在没有完全预见价格协调的情况下产生。在具有时间可分效用的条件下，我们证明了泛型禀赋存在一个一维的ETE分配集合。此外，这些有效的分配可以得到一个自由度上不一致的预测的支持。因此，尽管效率和完全竞争可能表现得很强，但它们并不意味着完全预见，但它们确实增加了对暂时均衡的解释力，因为它们从帕累托效率配置中选择了一个小子集，而帕累托效率配置通常具有更高的维度。
13.Bargaining in small dynamic markets
在充满活力的小市场中讨价还价
Francesc Dilmé
This paper studies trade in endogenously evolving markets exhibiting few traders at any given point in time. Traders arrive in the market and bargain until they complete a trade. We find that, unlike large markets, small markets feature trade delay and price dispersion, even when sellers and buyers are homogeneous and matching frictions are small. We characterize transaction prices as a function of the endogenous evolution of the market composition and economic conditions, providing several novel comparative statics results. Our analysis highlights the need to incorporate sub-market structures into the theoretical study of job, real estate, and rental markets, where trade opportunities are typically constrained by both the geographical location and individual characteristics of each trader.
本文研究了在任何给定时间点上交易者很少的内生演变市场中的交易。交易者进入市场讨价还价，直到完成交易。我们发现，与大型市场不同，小型市场具有交易延迟和价格离散的特征，即使在买卖双方同质且匹配摩擦较小的情况下也是如此。我们将交易价格刻画为市场构成和经济条件内生演化的函数，提供了几个新颖的比较静态分析结果。我们的分析强调了将子市场结构纳入就业、房地产和租赁市场的理论研究的必要性，在这些市场中，贸易机会通常受到地理位置和每个交易员的个人特征的限制。
14.Task allocation and on-the-job training
任务分配及在职培训
Mariagiovanna Baccara, SangMok Lee, Leeat Yariv
We study dynamic task allocation when providers' expertise evolves endogenously through training. We characterize optimal assignment protocols and compare them to discretionary procedures, where it is the clients who select their service providers. Our results indicate that welfare gains from centralization are greater when tasks arrive more rapidly, and when training technologies improve. Monitoring seniors' backlog of clients always increases welfare but may decrease training. Methodologically, we explore a matching setting with endogenous types, and illustrate useful adaptations of queueing theory techniques for such environments.
我们研究提供者的专业知识通过培训内生发展时的动态任务分配。我们描述了最佳分配协议的特征，并将其与酌情程序进行比较，在这些程序中，是客户选择其服务提供者。我们的结果表明，当任务到达得更快、培训技术提高时，集中化带来的福利收益更大。监控老年人积压的客户总是会增加福利，但可能会减少培训。在方法论上，我们探索了一个具有内生类型的匹配设置，并说明了排队论技术在这种环境下的有用适应性。
15.Global manipulation by local obfuscation
通过局部混淆进行全局操作
Fei Li, Yangbo Song, Mofei Zhao
We study adversarial information design in a regime-change context. A continuum of agents simultaneously chooses whether to attack the current regime. The attack succeeds if and only if the mass of attackers outweighs the regime's strength. A designer manipulates information about the regime's strength to maintain the status quo. Our optimal information structure exhibits local obfuscation: some agents receive a signal matching the regime's true strength, and others receive an elevated signal professing slightly higher strength. This policy is the unique limit of finite-signal problems. Public signals are strictly suboptimal, and in some cases where public signals become futile, local obfuscation guarantees the collapse of agents' coordination, making the designer's information disclosure time consistent and relieving the usual commitment concern.
我们研究了政权更迭背景下的对抗信息设计。一个连续的代理人同时选择是否攻击当前的政权。当且仅当攻击者的数量超过叙利亚政权的力量时，攻击才会成功。设计师通过操纵有关政权实力的信息来维持现状。我们的最优信息结构表现出局部混淆:一些代理接收到与政权真实强度相匹配的信号，而另一些代理接收到强度略高的高信号。该策略是有限信号问题的唯一极限。公共信号是严格次优的，在某些公共信号无效的情况下，局部混淆保证了代理人协调的崩溃，使设计者的信息披露时间一致，缓解了通常的承诺担忧。
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