Efficient Design with Interdependent Valuations
研究存在信息和分配外部性时，满足有效性和激励相容的机制存在的条件，发现多维信号下仅当估值私有或对称性成立时才有可能，而一维信号下可普遍满足，并讨论了多物品拍卖不能简化为单维模型的原因。
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 signals are multi-dimensional, the congruence condition is determined by an integrability constraint, and it can hold only in nongeneric cases where values are private or a certain symmetry assumption holds. If signals are one-dimensional, the congruence condition reduces to a monotonicity constraint and it can be generically satisfied. We apply the results to the study of multi-object auctions, and we discuss why such auctions cannot be reduced to one-dimensional models without loss of generality.