Designing Markets with Complementarities

如果没有明确的规则和协调的交易，许多现实世界的市场就会运转不良。发电供应必须随时满足需求，否则就会出现轮流停电。如果地方当局不集中小学招生，许多家长将被迫接受孩子无法茁壮成长的学校。如果政府免费发放移动频谱许可证，那么频谱可能不会最终落入能够为公众提供最佳服务的电信公司手中。许多市场可以通过运用经济学分支“市场设计”的洞见得到大幅改善。市场设计者运用经济理论制定市场规则，创造促进市场交易的基础设施。公司股票、大宗商品甚至电力都在有组织的交易所进行交易。集中的双边配对市场用于医生与医院、儿童与学校和大学、不相容的肾供-患配对、军校学员与兵种之间的配对。拍卖被用来为大量的移动频谱、珍贵的古董和搜索引擎广告寻找最有意愿的买家。市场设计师已经创造了许多方法来设计市场，使其能够完美地分配相似（相同或可替代）的商品。这些措施包括古董拍卖，以及地方政府为分配孩子上小学而采用的基于偏好的匹配制度。但使市场设计变得极其复杂的一个特殊特征是互补性。当事物的价值总和大于它们各自部分的总和时，它们就是互补的。回到上面的一个例子，假设政府想要出售移动频谱许可证。电信公司非常看重附近的牌照，因为这可以让他们为客户提供更好的服务。政府应该将附近的许可证捆绑在一起还是单独出售？现在假设为了向电信公司出售频谱许可证，政府首先必须从数百家电视台购买这些频谱许可证。政府是否应该同时购买和出售这些许可证？最后，假设政府也可以将一些电视台转移到频谱的其他部分进行广播。在避免广播干扰的情况下，它应该移动哪些电台？回答所有这些问题需要解决不同类型的互补性。现实世界中还有其他具有互补性的市场例子。在土地拍卖中竞标的房地产开发商通常希望购买邻近的地块。船长经常想用他们的捕捞配额来交换其他物种的配额。为了避免停电，电网运营商必须确保某些化石燃料和可再生能源发电机同时发电。这些例子清楚地表明，在互补性存在的情况下，市场设计对于确保市场良好运作至关重要。需要进行协调，以确保尽可能多地进行补充交易。然而，当存在互补性时，简单、经典的拍卖和匹配算法可能会严重失败。因此，需要新的理论工具。在这项工作中，我开发了新的理论和实践工具——拍卖、匹配市场和交易网络——来设计具有不同类型互补性的市场。我还在一系列的实验室实验中测试了一个新的拍卖。这项工作在重新设计许多现有市场和设计新市场方面有许多重要的应用，包括生物多样性保护市场、点对点能源交易市场、渔业配额拍卖和交换市场以及分配重新安置难民的匹配系统。

Many real-world markets would function poorly if they did not have clear rules and coordinated transactions. The supply of generated electricity must match demand at all times otherwise there will be rolling blackouts. If local authorities do not centralise primary school admissions, many parents would be pressured into accepting places in schools where their children would not thrive. If the government gives away mobile spectrum licenses for free, then spectrum might not end up with telecoms companies that can provide the best service for the public.Many markets can be drastically improved using insights from a branch of economics called "market design". Market designers use economic theory to develop market rules and create infrastructure that facilitates market transactions. Company shares, commodities, and even electricity are traded in organised exchanges. Centralized two-sided matching markets are used to match doctors to hospitals, children to schools and universities, one incompatible kidney donor-patient pair to another, and army cadets to branches of service. Auctions are used to find the most willing buyers for swathes of mobile spectrum, precious antiques, and search engine adverts. Market designers have created many ways to design markets that superbly allocate similar (identical or substitutable) items. These include auctions for antiques and preference-based matching systems used by local authorities to allocate children to primary schools. But one particular feature that drastically complicates the design of markets is complementarity. Things are complements when the value of them together is greater than the sum of their individual parts. Coming back to an example above, suppose that the government wanted to sell mobile spectrum licenses. Telecoms companies value nearby licenses a great deal as it allows them to provide a better service for customers. Should the government bundle nearby licenses together or sell them separately? Now suppose that in order to sell spectrum licenses to telecoms companies the government first has to buy these spectrum licenses from hundreds of television stations. Should the government buy and sell these licenses at the same time? Finally, suppose that the government could also move some television stations to broadcast on other parts of the spectrum. Which stations should it move while avoiding broadcast interference? Answering all these questions involves tackling different types of complementarity.There are other examples of real-world markets with complementarities. Property developers bidding in a land auction often want to buy adjacent plots of land. Boat captains often want to exchange some of their fishing quota for quota of other species. In order to avoid blackouts, the electricity grid operator has to make sure that certain fossil fuel and renewable generators are producing energy at the same time.These examples make clear that in the presence of complementarities market design can be crucial to ensure the market works well. Coordination is required to ensure that as many of the complementary transactions take place as possible. However, when there are complementarities, simple, classic auctions and matching algorithms can fail dramatically. Therefore new theoretical tools are needed.In this work, I develop new theoretical and practical tools - auctions, matching markets, and trading networks - to design markets with different types of complementarity. I also test one new auction in a series of laboratory experiments. This work has a number of important applications for the redesign of many existing markets and for the design of new ones, including markets for biodiversity conservation, peer-to-peer energy trading, auctions and exchanges of fishing quota, and matching systems for the allocation of resettled refugees.