An important result in convex analysis is the duality between a closed convex set and its support function. We exploit this duality to develop a novel geometric approach to mechanism design. For a general class of social choice problems we characterize the feasible set, which is closed and...

An auction is externality-robust if unilateral deviations from equilibrium leave the other bidders' payoffs unaffected. The equilibrium and its outcome will then persist if certain types of externalities arise between bidders. One example are externalities due to spiteful preferences, which have...

We introduce a general class of simplicity standards that vary the foresight abilities required of agents in extensive-form games. Rather than planning for the entire future of a game, agents are presumed to be able to plan only for those histories they view as simple from their current...

We introduce intention-based social preferences into a Bayesian mechanism design framework. We first show that, under common knowledge of social preferences, any tension between material efficiency, incentive compatibility, and voluntary participation can be resolved. Hence, famous impossibility...

The endowment and attachment effect are empirically well-documented in bilateral trade situations. Yet, the theoretical literature has so far failed to formally identify these effects. We fill this gap by introducing expectations-based loss aversion, which can explain both effects, into the...

The endowment and attachment effect are empirically well-documented in bilateral trade situations. Yet, the theoretical literature has so far failed to formally identify these effects. We fill this gap by introducing expectations-based loss aversion, which can explain both effects, into the...

We consider a dynamic auction environment with a long-lived seller and short-lived buyers mediated by a third party. A mediator has incomplete information about traders' values and selects an auction mechanism to maximize her expected revenue. We characterize mediator-optimal mechanisms and show...

In contexts in which players have no priors, we analyze a learning process based on ex-post regret as a guide to understand how to play games of incomplete information under private values. The conclusions depend on whether players interact within a fixed set (fixed matching) or they are...

We apply stochastic stability to study the evolution of bidding behavior in private-values second-price, first-price and k-double auctions. The learning process has a strong component of inertia but with a small probability, the bids are modified in the direction of ex-post regrets. We identify...

Transaction costs are omnipresent in markets yet are often omitted in economic models. We show that their presence can fundamentally alter incentives and welfare in markets in which the price equates supply and demand. We categorize transaction costs into two types. Asymptotically...