Single Price Mechanisms for Revenue Maximization in Unlimited Supply Combinatorial Auctions

In this note we generalize a result of Guruswami et. al [7], sh owing that in unlimited-supply combinatorial auctions, a surprisingly simple mechanism that offe rs the same price for each item achieves revenue within a logarithmic factor of the total social welfare for b idders with general valuation functions (not just single-minded or unit-demand bidders as in [7]). We als o extend this to the limited-supply setting for the special case of bidders with additive valuations. Th ese are both settings for which Likhodedov and Sandholm [9] provide logarithmic approximations bu t via much more complex bundle-pricing mechanisms.