We study the existence of efficient, Bayesian incentive compatible allocation procedures in a general setting with interdependent valuations. Possible applications include multi-object auctions and the provision of public goods. We emphasize the role of multidimensional signals, and, in view of...

We study efficient, Bayes-Nash incentive compatible mechanisms in a social choice setting that allows for informational and allocative externalities. We show that such mechanisms exist only if a congruence condition relating private and social rates of information substitution is satisfied. If...

In our framework, when a buyer does not obtain the auctioned object, he is no longer indifferent about the identity of the winner (i.e., eyternal effects are present). Buyer i's preferences are characterized by an N-dimensional vector t^i = (t1^i, t2^i,..,tN^i). The coordinate ti^i can be...

An indivisible good can be consumed by one of several agents. The consumption involves identity-dependent externalities to non-consumers. Resale markets for such goods are analyzed in various institutional settings where agents cannot commit to future actions. We address the following questions:...

We study auctions for an invisible object. The outcome of the auction influences the future interaction among agents. The impact of that interaction on agent's is assumed to be a function of the agent's valuations. While agent's i valuation is private information to i, the other valuations are...

We study optimal contest design in situations where the designer can reward high performance agents with positive prizes and punish low performance agents with negative prizes. We link the optimal prize structure to the curvature of distribution of abilities in the population. In particular, we...

We briefly survey several insights about value and revenue maximization in multi-object auctions and apply them to the German (and Austrian) UMTS auction. In particular, we discuss in detail the exposure problem that caused firms in Germany to pay almost Euro 20 billion for nothing.