Package bids, i.e., bids on sets of items, are an essential aspect of combinatorial auctions. They can allow bidders to accurately express their preferences. However, bidders on packages consisting of few items are often unable to outbid provisionally winning bids on large packages. To resolve this, both coordination as well as cooperation are needed. Coordination, since smaller bidders need to bid on packages that are disjoint; cooperation, since typically bid increases from more than one bidder are required to overcome the threshold to outbid a larger package bid. The authors design an information system that supports the implementation of an iterative combinatorial auction; this system is specifically aimed at helping bidders overcome coordination and threshold problems. They study the effect of information feedback on the behavior of bidders in different auction settings. The authors test this in an experimental setting using human bidders, varying feedback from very basic information about provisionally winning bids/prices, to providing more advanced concepts such as winning and deadness levels, and coalitional feedback. The experiment indicates that coalitional feedback has a positive impact on economic efficiency in cases where difficult threshold problems arise; however, it appears to have an adverse effect when threshold problems are easy.

中文翻译：

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使用反馈来缓解迭代组合拍卖中的协调和阈值问题

一揽子投标，即对一组项目的投标，是组合拍卖的一个重要方面。他们可以让投标人准确地表达他们的偏好。然而，由少量物品组成的包裹的投标人通常无法胜过临时中标大包裹的投标。要解决这个问题，既需要协调，也需要合作。协调，因为较小的投标人需要对不相交的包裹进行投标；合作，因为通常需要从不止一个投标人那里增加投标，以克服门槛以超过更大的一揽子投标。作者设计了一个支持迭代组合拍卖实施的信息系统；该系统专门用于帮助投标人克服协调和门槛问题。他们研究了信息反馈对不同拍卖环境中投标人行为的影响。作者在一个实验环境中使用人类投标人对此进行了测试，从关于临时中标/价格的非常基本的信息到提供更高级的概念（如获胜和死率水平以及联合反馈）的不同反馈。实验表明，在出现困难阈值问题的情况下，联合反馈对经济效率有积极影响；然而，当阈值问题很容易时，它似乎会产生不利影响。和联合反馈。实验表明，在出现困难阈值问题的情况下，联合反馈对经济效率有积极影响；然而，当阈值问题很容易时，它似乎会产生不利影响。和联合反馈。实验表明，在出现困难阈值问题的情况下，联合反馈对经济效率有积极影响；然而，当阈值问题很容易时，它似乎会产生不利影响。