An Improved 2-Agent Kidney Exchange Mechanism

  • Ioannis Caragiannis
  • Aris Filos-Ratsikas
  • Ariel D. Procaccia
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7090)


We study a mechanism design version of matching computation in graphs that models the game played by hospitals participating in pairwise kidney exchange programs. We present a new randomized matching mechanism for two agents which is truthful in expectation and has an approximation ratio of 3/2 to the maximum cardinality matching. This is an improvement over a recent upper bound of 2 [Ashlagi et al., EC 2010] and, furthermore, our mechanism beats for the first time the lower bound on the approximation ratio of deterministic truthful mechanisms. We complement our positive result with new lower bounds. Among other statements, we prove that the weaker incentive compatibility property of truthfulness in expectation in our mechanism is necessary; universally truthful mechanisms that have an inclusion-maximality property have an approximation ratio of at least 2.


Approximation Ratio Electronic Commerce Input Graph Maximum Cardinality White Node 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • Ioannis Caragiannis
    • 1
  • Aris Filos-Ratsikas
    • 1
  • Ariel D. Procaccia
    • 2
  1. 1.Department of Computer Engineering and InformaticsUniversity of PatrasRioGreece
  2. 2.Computer Science DepartmentCarnegie Mellon UniversityPittsburghUSA

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