Efficient Auctions
提出一种在共同价值下也能实现效率的拍卖机制，适用于买家信息为一维信号的情形；当信息多维时，该机制在激励约束下达到约束效率。
We exhibit an <it>efficient auction</it> (an auction that maximizes surplus conditional on all available information). For private values, the Vickrey auction (for one good) or its Groves-Clarke extension (for multiple goods) is efficient. We show that the Vickrey and Groves-Clarke auctions can be generalized to attain efficiency when there are common values, if each buyer's information can be represented as a one-dimensional signal. When a buyer's information is multidimensional, no auction is generally efficient. Nevertheless, in a broad class of cases, our auction is <it>constrained-efficient</it> in the sense of being efficient subject to incentive constraints.