Mix and Match: A Strategyproof Mechanism for

As kidney exchange programs are growing, manipulation by hospitals be-comes more of an issue. Assuming that hospitals wish to maximize the number of their own patients who receive a kidney, they may have an incen-tive to withhold some of their incompatible donor-patient pairs and match them internally, thus harming social welfare. We study mechanisms for two-way exchanges that are strategyproof, i.e., make it a dominant strategy for hospitals to report all their incompatible pairs. We establish lower bounds IWe have benefited from valuable discussions with Moshe Tennenholtz and Davi