cient and Incentive Compatible Exchange of Real - Time Information ∗

We consider the problem of coordinating the exchange of real-time information among multiple agents. For example, a US Department of Transportation pilot program seeks to reduce tra c accidents by allowing each vehicle to request and send crash-relevant information (e.g. position, speed, braking status) from and to neighboring vehicles. Time is of the essence: vehicle information becomes stale quickly. We model information as discrete, indivisible objects. Electronic les, the medium of information, are corrupt/useless when partial, hence we treat them as indivisible. Each agent may perfectly replicate an object in his possession and transfer it to another agent. However, replication and transfer takes time (e.g. due to bandwidth constraints), and scarcity arises due to fact that information quickly becomes valueless. How should agents transfer such objects? We study e ciency, strategy-proofness, withholding-proofness, and introduce a new axiom based on the concept of reciprocity. Our results are as follows: When each agent owns one object and consumes only one object, we identify a family of rules satisfying all four axioms. If each agent owns a bundle of objects and consumes a bundle, then the four axioms are incompatible. If agents live in an (incomplete) network, then e ciency is only compatible with strategy-proofness.