Adword拍卖中的能力约束和中介者的必然性
Capacity constraints and the inevitability of mediators in adword auctions
摘要：
赞助搜索广告框架中的一个自然约束来自于以下事实：存在对可用槽的数量的限制，特别是对于流行关键字，并且因此，大量广告商被排除在外。我们研究了这种容量限制引发的广告市场多样化的出现，在这个意义上，新的市场机制，以及新的营利性代理可能会出现打击或从广告空间库存短缺所创造的机会中获利。我们提出了一个模型，其中额外的容量是由营利性代理商（或调解员），谁在原来的拍卖竞争插槽，吸引流量，并运行自己的子拍卖。中介体提供的额外能力的质量由其{ \it适应度}因子来衡量。当基于中介的模型由谷歌和雅虎目前使用的机制操作时，我们计算所有不同方在{ \it对称纳什均衡}（SNE）的收入和收益，然后将这些数字与在相同机制的相应SNE处获得的那些数字进行比较，但是在拍卖中不涉及任何中介。这样的计算使我们能够确定额外容量的价值。我们的研究结果表明，拍卖商的收入，以及社会价值（即效率），总是增加时，调解人的参与;此外，甚至{ \em所有}投标人的收益将增加，如果调解人有足够高的适应度。因此，我们的分析表明，在互联网经济中存在着巨大的多元化机会，我们应该期待它继续发展更丰富的结构，为不同类型的代理人和机制提供共存的空间。
英文摘要：
One natural constraint in the sponsored search advertising framework arises from the fact that there is a limit on the number of available slots, especially for the popular keywords, and as a result, a significant pool of advertisers are left out. We study the emergence of diversification in the adword market triggered by such capacity constraints in the sense that new market mechanisms, as well as, new for-profit agents are likely to emerge to combat or to make profit from the opportunities created by shortages in ad-space inventory. We propose a model where the additional capacity is provided by for-profit agents (or, mediators), who compete for slots in the original auction, draw traffic, and run their own sub-auctions. The quality of the additional capacity provided by a mediator is measured by its {\it fitness} factor. We compute revenues and payoffs for all the different parties at a {\it symmetric Nash equilibrium} (SNE) when the mediator-based model is operated by a mechanism currently being used by Google and Yahoo!, and then compare these numbers with those obtained at a corresponding SNE for the same mechanism, but without any mediators involved in the auctions. Such calculations allow us to determine the value of the additional capacity. Our results show that the revenue of the auctioneer, as well as the social value (i.e. efficiency), always increase when mediators are involved; moreover even the payoffs of {\em all} the bidders will increase if the mediator has a high enough fitness. Thus, our analysis indicates that there are significant opportunities for diversification in the internet economy and we should expect it to continue to develop richer structure, with room for different types of agents and mechanisms to coexist.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
