We consider the provision of an abstract service to single-dimensional agents. Our model includes position auctions, single-minded combinatorial auctions, and constrained matching markets. When the agents' values are drawn independently from a distribution, the Bayesian optimal mechanism is...

We study environments with m homogenous items and two bidders, where the private information of each bidder consists of a monotone valuation (multi-unit auctions). We analyze ex-post implementable social choice functions where the dominant strategy of a bidder is to reveal his valuation.