SPECIAL TIME: 1:30 -- 2:20 pm, Tuesday, Jan 20, 2009 PLACE: CSE 503 SPEAKER: Jason Hartline Northwestern University TITLE: Approximation in Multi-dimensional Mechanism Design ABSTRACT: Over the last decade methodologies from the microeconomics subfield of mechanism design have been imported into computer science to study the design of algorithms in economic settings such as the Internet. Much of the effort in these studies has been on merging computer science mindsets of "worst-case" and "poly-time" leaving untouched the most important open question in economics, i.e., identifying the mechanism by which a seller facing agents with multi- dimensional preferences drawn from a known distribution can maximize profit. In such a setting there is clearly a mechanism, over the class of all mechanisms, that achieves the highest expected profit in (Bayes-Nash) equilibrium. What is it? In this talk I will show how, with the notion of approximation, one of the most important exports form computer science into economics, we are able to get a succinct, and intuitive description of a near-optimal mechanism for a multi-item unit-demand pricing problem (e.g., there are multiple houses for sale, a buyer wants to buy a house, they have an independently drawn value for each house, given prices on each house they will choose the one that maximizes their utility = value - price, how can we price the houses to maximize the seller's profit). We give a simple three approximation that is based heavily on Myerson's (1981) theory of optimal auctions in single-dimensional settings.