The Asymmetric Matrix Partition Problem -- Polylogarithmic Supports are required for Approximate Well-Supported Nash Equilibria -- The Computational Complexity of Random Serial Dictatorship -- Incentives and Efficiency in Uncertain Collaborative Environments -- Revenue Maximization with Nonexcludable Goods -- On Lookahead Equilibria in Congestion Games -- Trading Agent Kills Market Information: Evidence from Online Social Lending -- Designing Markets for Daily Deals -- The Exact Computational Complexity of Evolutionarily Stable Strategies -- The Price of Anarchy of the Proportional Allocation Mechanism Revisited -- Valuation Compressions in VCG-Based Combinatorial Auctions -- Limits of Efficiency in Sequential Auctions -- Competition in the Presence of Social Networks: How Many Service Providers Maximize Welfare? -- Resolving Braess's Paradox in Random Networks -- A protocol for cutting matroids like cakes -- Quantitative Comparative Statics for a Multimarket Paradox -- Price of Anarchy for the N-player Competitive Cascade Game with Submodular Activation Functions.

This book constitutes the thoroughly refereed conference proceedings of the 9th International Conference on Web and Internet Economics, WINE 2013, held in Cambridge, MA, USA, in December 2013. The 36 revised full papers were carefully reviewed and selected from 150 submissions and cover research in theoretical computer science, artificial intelligence, and microeconomics.