Intermediation, Information, and Diversity in Networks

网络在经济和社会环境中无处不在。个人的决定和福利受到当地联系以及全球网络结构的影响。该奖项资助的研究调查了代理人互动的网络如何影响各种市场和群体活动的结果。有三个不同的项目。前两个研究网络结构对贸易中介和信息扩散的影响。第三个项目研究什么样的网络特征对于在受社会影响的选择中保持多样性是必不可少的。该理论认为，卖方的利润不仅取决于沿着的中间商数量，还取决于每个中间商提供的进入买方的竞争路径的完整集合。卖方更愿意沿着这样的路径进行交易，即在具有类似转售价值的中间商之间进行当地竞争。贸易途径并不一定最大限度地减少中介或最大限度地提高福利。将网络分解为中介力量的层次，是均衡转售利润的特征。地方竞争在层次内被利用，跨层次交易中出现套牢问题。这项研究对打击有组织犯罪和非法贸易、防止等级结构中的腐败以及供应链中的高效生产具有影响。第二个项目研究信息（技术创新，研究思路，新闻和八卦）是如何定价和传播网络的链接。与对中介的研究相反，信息商品是非竞争性的;任何拥有该商品的参与者随后都可以复制并转售给任意数量的不知情的邻居。信息最初来源在网络中的位置影响到行为者从获取和转售信息中获得的利润，并影响到传播过程。卖家为争夺客户而竞争，并在网络中建立各自的势力范围。 主要目的是证明利润被限制在一定的网络分区的块。同一区块内端点的链接构成瓶颈，在获取利润方面发挥着重要作用。跨区块的链接在连接网络方面并不重要，并对卖方造成了负面的外部性。第三个项目考虑的是一个网络中的玩家需要采取行动或形成与大多数邻居一致的意见的设置。对任何特定行动的一致协调构成了一种均衡。许多网络还具有不同行动选择的均衡。本研究的目的是表征网络的多样性是强大的引入随机突变的最佳响应动态。 本研究中开发的工具和方法将通过使企业和政策制定者更好地了解网络关系如何影响市场结果，从而产生更广泛的影响。

Networks are ubiquitous in economic and social contexts. Individual decisions and welfare are affected by local connections, as well as by global network architecture. The research funded by this award investigates how the networks in which agents interact influence outcomes in a variety of market and group activities. There are three distinct projects. The first two investigate the impact of network structure on trade intermediation and information diffusion. The third project examines what network features are essential for the persistence of diversity in socially influenced choices.The first project studies intermediation in networks. The theory suggests that the seller's profit depends not only on the number of middlemen along the path of trade, but also on the complete collection of competing paths of access to buyers offered by each middleman. The seller prefers to trade along paths that entail local competition among intermediaries with similar resale values. Trading paths do not necessarily minimize intermediation or maximize welfare. A decomposition of the network into layers of intermediation power characterizes equilibrium resale profits. Local competition is exploited within layers and hold-up problems arise in transactions across layers. This research has implications for combating organized crime and illegal trade, preventing corruption in hierarchical structures, and efficient production in supply chains. The second project investigates how information (technological innovations, research ideas, news and gossip) is priced and diffused across the links of a network. In contrast to the research on intermediation, the information good is non-rival; any player who gets possession of the good may subsequently replicate and resell it to an arbitrary number of uninformed neighbors. The positions of the initial sources of information in the network affect the profits that actors accrue from acquiring and reselling the information and shape the diffusion process. Sellers compete for customers and establish individual spheres of influence in the network. The main objective is to prove that profits are confined within the blocks of a certain network partition. Links with endpoints within the same block constitute bottlenecks and play an important role in extracting profits. Links bridging across blocks are not critical in connecting the network and impose negative externalities on sellers. The third project considers a setting where players situated in a network need to take actions or form opinions that conform with a majority of their neighbors. Unanimous coordination on any particular action constitutes an equilibrium. Many networks also feature equilibria with diverse action choices. The aim of this research is to characterize the networks for which diversity is robust to the introduction of stochastic mutations in the best response dynamic. The tools and methods developed in this research will provide broader impact by allowing firms and policymakers to better understand how network relationships affect market outcomes.