Collusion in Second‐Price Auctions under Minimax Regret Criterion

Collusion in auctions, with different assumptions on distributions of bidders' private valuation, has been studied extensively over the years. With the recent development of on‐line markets, auctions are becoming an increasingly popular procurement method. The emergence of Internet marketplaces makes auction participation much easier and more convenient, since no physical presence of bidders is required. In addition, bidders in on‐line auctions can easily switch their identities. Thus, it may very well happen that the bidders in an auction have very little, if any, prior knowledge about the distributions of other bidders' valuations. We are proposing an efficient distribution of collusive profit for second‐price sealed bid auctions in such an environment. Unlike some known mechanism, which balance the budget only in expectation, our approach (which we call Random k) balances the budget ex‐post. While truth‐telling is not a dominant strategy for Random k, it is a minimax regret equilibrium.     

Bounds of Relative Regret Limit in p‐Robust Supply Chain Network Design

This research studies the p‐robust supply chain network design with uncertain demand and cost scenarios. The optimal design integrates the supplier selection together with the facility location and capacity problem. We provide a new framework to obtain the relative regret limit, which is critical in the robust supply chain design but is assumed to be a known value in the existing literature. We obtain lower and upper bounds for relative regret limit and obtain a sequence of optimal solutions for series relative regret limits between the upper and lower bounds. An algorithm for p‐robust supply chain network design is provided. A series of numerical examples are designed to find the properties of the bottleneck scenarios. A scenario with low probability and a low optimal objective function value for the scenario has a greater chance of being a bottleneck. To focus only on the influence from the relative regret, we also introduce three separate new objective functions in p‐robust design. The proposed new theories and approaches provide a sequence of options for decision makers to reduce the marketing risks effectively in supply chain network design.     

论后悔权中商品完好要件的证明责任

对于后悔权中商品完好要件的客观证明责任,基于大陆、英美法系学理的分析无法得出明确结论;基于我国的现行法律研究得出的结论,由于其理论基础与《中华人民共和国消费者权益保护法》的立法趣旨相悖而有失妥当;从后悔权的趣旨和法经济学出发,应由经营者承担。对于主观证明责任,证明活动参与方应积极协同;同时充分利用表见证明、证明妨碍、主观具体证明责任转换等理论,推动证明活动呈近似正弦曲线的轨迹展开。由于经营者反驳后悔权的理由各异,有必要运用类型化分析方法展开不同理由下的证明活动。     

有限需求信息下基于回购契约的供应链鲁棒协调策略

研究了仅知需求均值和区间信息条件下,基于最小最大后悔值准则的供应链回购契约协调问题。针对未知需求具体分布形式的两级供应链系统,在回购契约框架下,建立了以鲁棒决策和最优决策下的供应链及其成员绩效之差为目标函数的供应链协调模型。在仅知需求区间和均值信息条件下,采用鲁棒优化方法求解了最小最大后悔值准则下的集成供应链鲁棒订货策略和分散供应链鲁棒契约协调策略及其绩效偏差。分析了不同服务水平和契约参数条件下,由于信息缺失而未能实现最优运作的供应链及其成员绩效损失情况。最后,进行了数值计算,验证了通过鲁棒优化方法得到的供应链回购契约协调策略的鲁棒性和有效性。结果表明,基于回购契约的供应链鲁棒协调策略能够有效抑制需求不确定性对系统及其成员运作绩效的影响,同仅知需求区间信息相比,额外获得需求均值信息能够有效改进供应链运作绩效。     

追求完美中的遗憾--我五十多年来的文化学术道路

我的文化学术道路,涉及三个学科(鲁迅研究,二十世纪中国文学史,文艺学方法论).我自幼酷爱鲁迅,自从1955年考取南开大学副博士后,鲁迅研究应该是我的正业.遗憾的是,在"左"的大潮裹挟下,我走过一段弯路.如梦初醒,已是两鬓霜染,首先是一大遗憾.在高校教书,除了深必须广,领导上交给了我一个大题目:<二十世纪中国文学大典>,我力求完美,但遭遇的是遗憾,十年"文革"的资料统统被删去,计50万字,结果只剩了二本半.不能不使我感到深深的遗憾.在八十年代中期,文艺学方法论热,但抄抄编编多,出类拔萃者少之又少,我夙好西方哲学,对康德、黑格尔寝馈有年,从这个水平看,愈觉寥寥.古人说,世无英雄,遂使竖子成名.我的<文艺学方法论>自1991年上海文艺出版社出版以来,到2004年7月由复旦大学出版社第二版第二次印刷,近10000册,我这本书在这一学科中十二年来始终处于高端.可是正在这丰收的愉悦中,我却得了心脑血管病和严重的三叉神经病,时时呻吟,读写俱废,这是我生存受到威胁的最大的遗憾,也是我追求完美的最大的遗憾,假使不生这些病,身体完好如初,我可以写部<鲁迅杂文研究>和<二十世纪中国文学史>(已谢绝了人民文学出版社的稿约).     

MSE Performance and Minimax Regret Significance Points for a HPT Estimator when each Individual Regression Coefficient is Estimated

In this article, we consider a heterogeneous preliminary test (HPT) estimator whose components are the OLS and feasible ridge regression (FRR) estimators, and derive the exact formulae for the moments of the HPT estimator using mathematical method. Since we cannot examine the MSE of the HPT estimator analytically, we execute the numerical evaluation to investigate the MSE performance of the HPT estimator, and compare the MSE performance of the HPT estimator with those of the FRR estimator and the usual OLS estimator. Furthermore, using the minimax regret criterion proposed by Sawa and Hiromatsu (1973 Sawa , T. , Hiromatsu , T. ( 1973 ). Minimax regret significance points for a preliminary test in regression analysis . Econometrica 41 : 1093 – 1101 .[Crossref], [Web of Science ®] , [Google Scholar]), we derive the optimal critical points of the preliminary F test. Our results show that the optimal significance points are greater than 19% and the optimal signicance points decrease as the denominator degrees of freedom of the preliminary F test statistic increases.     

从文化精神论庾信后期的愧悔心态

度信入北以后的诗文多抒发家国俱亡、天涯羁旅的痛苦情思,而实际上亡国之痛和乡关之思的背后隐藏着其后期最为深重的精神痛苦——对自身失节的愧悔。庾信的愧悔作为一种文化心态具有深厚的人文背景,因而具有丰富的内涵和独特的文化价值。     

Informational Asymmetries and Observational Learning in Search

As economics modeling moves from super rational decision makers to considering boundedly rational agents, some economic problems deserve a second look. This paper studies the effects of learning on the efficiency of search. Once learning is taken into account, the structure of information flow becomes important. In particular, I highlight the truncated information structure in the search problem. Agents stop searching once a sufficiently attractive price is found. Therefore, they observe the performance of shorter searches, but do not directly observe the performance of longer searches. I design and conduct an experiment to test the hypothesis that this asymmetric flow of information leads agents to search too little. I find strong evidence in its favor. This suggests that in the presence of learning, the provision of a more symmetric information structure will make search more efficient.JEL Classification: C91, D83