A collaborative filtering system recommends to users products that similar users like. Collaborative fi ltering systems influence purchase decisions, and hence have become targets of manipulation by unscrupulous vendors. We provide theoretical and empirical results demonstrating that while...

Ad Exchanges are emerging Internet markets where advertisers may purchase display ad placements, in real-time and based on specific viewer information, directly from publishers via a simple auction mechanism. Advertisers join these markets with a pre-specified budget and participate in multiple...

In this paper we study the implications of service level guarantees (SLGs) in a model of oligopoly competition where providers compete to deliver a service to congestion-sensitive consumers. The SLG is a contractual obligation on the part of the service provider: regardless of how many customers...