If A is a set of social alternatives, a social choice rule (SCR) assigns a subset of A to each potential profile of individuals' preferences over A, where the subset is interpreted as the set of "welfare optima". A game form (or "mechanism") implements the social choice rule if, for any...

The authors exhibit an efficient auction (i.e., an auction that maximizes expected surplus conditional on all private and public information). In the case of private value, it is well-known that the Vickrey auction (for one good) or its Groves-Clark extension (for multiple goods) is efficient in...

The paper characterises the choice rules that can be implemented when agents are unable to commit themselves not to renegotiate the mechanism.

This paper develops a model of pricing to deter entry by a sole supplier of a network good. The authors show that the installed user base of a network good can serve a preemptive function similar to that of an investment in capacity if the entrant's good is incompatible with the incumbent's good...

Firms sometimes try to "poach" the current customers of their competitors by offering them special inducements to switch. The authors analyze duopoly poaching under both short-term and long-term contracts in two polar cases: either each consumer's brand preferences are constant from one period...

This paper explores a monopolist's incentives to provides upgraded versions of its software. In particular, the authors examine how market power, commitment problems and price discrimination may lead a monopolistice supplier of a network good to introduce upgrades when social welfare would be...