Sort-Cut: A Pareto Optimal and Semi-Truthful Mechanism for Multi-Unit Auctions with Budget-Constrained Bidders

I. Hafalir,R. Ravi,Amin S. Sayedi-Roshkhar

Published 2009 in arXiv.org

ABSTRACT

Motivated by sponsored search auctions with hard budget constraints given by the advertisers, we study multi-unit auctions of a single item. An important example is a sponsored result slot for a keyword, with many units representing its inventory in a month, say. In this single-item multi-unit auction, each bidder has a private value for each unit, and a private budget which is the total amount of money she can spend in the auction. A recent impossibility result [Dobzinski et al., FOCS’08] precludes the existence of a truthful mechanism with Paretooptimal allocations in this important setting. We propose Sort-Cut, a mechanism which does the next best thing from the auctioneer’s point of view, that we term semi-truthful. While we are unable to give a complete characterization of equilibria for our mechanism, we prove that some equilibrium of the proposed mechanism optimizes the revenue over all Pareto-optimal mechanisms, and that this equilibrium is the unique one resulting from a natural rational bidding strategy (where every losing bidder bids at least her true value). Perhaps even more significantly, we show that the revenue of every equilibrium of our mechanism differs by at most the budget of one bidder from the optimum revenue (under some mild assumptions).

PUBLICATION RECORD

  • Publication year

    2009

  • Venue

    arXiv.org

  • Publication date

    2009-03-08

  • Fields of study

    Mathematics, Computer Science, Economics

  • Identifiers
  • External record

    Open on Semantic Scholar

  • Source metadata

    Semantic Scholar

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REFERENCES

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