We fully characterize the preferences relations that can be represented by a utility. Representation is equivalent to the condition that preferences do not have too many "jumps". A characterization of preferences that can be represented by a continuous utility follows trivially from our...

We consider preference relations over information that are monotone: more information is preferred to less. We prove that, if a preference relation on information about an uncountable set of states of nature is monotone, then it is not representable by a utility function.

We consider preference relations over information that are monotone: more information is preferred to less. We prove that, if a preference relation on information about an uncountable set of states of nature is monotone, then it is not representable by a utility function.

We comment on the relation between models of information based on signals/partitions, and those based on sigma-algebras. We show that more informative signals need not generate finer sigma-algebras, hence that Blackwell's theorem fails if information is modeled as sigma-algebras. The reason is...

We prove that the English auction (with bidders that need not be ex ante identical and may have interdependent valuations) has an efficient ex post equilibrium. We establish this result for environments where it has not been previously obtained. We also prove two versions of the...

We prove that the English auction (with bidders that need not be ex ante identical and may have interdependent valuations) has an efficient ex post equilibrium. We establish this result for environments where it has not been previously obtained. We also prove two versions of the...

We consider preference relations over information that are monotone: more information is preferred to less. We prove that, if a preference relation on information about an uncountable set of states of nature is monotone, then it is not representable by a utility function.

Auction theory has emphasized the importance of private information to the profits of bidders. However, the theory has failed to consider the question of whether or not bidders will be able to keep their information private. We show that in a variety of contexts bidders will reveal all their...

Policemen are known to support colleagues who are the subject of criminal investigations. While we might expect guilty officers to defend each other, why do law-abiding policemen defend those who have broken the law? We investigate under what conditions it is in the interest of a group to defend...