Title: Competition and Mediators

Abstract:
In this talk we discuss some challenges in the game-theoretic analysis of ad auctions. First, we discuss the topic of competition in ad auctions, where more than a single authority conducts an auction for a given keyword. In particular, we address the problem of whether higher click-rates lead to higher revenues in ad auctions. Second, we discuss the use of mediators in ad auctions, and characterize the welfare maximizing position auctions which possess ex-post equilibrium through mediation.