Robust Implementation in Direct Mechanisms
研究在相互依赖价值环境中，直接机制如何通过严格事后激励相容和收缩性质实现稳健实施，即迭代剔除严格占优策略后结果与社会选择函数一致。
A social choice function is robustly implementable if there is a mechanism under which the process of iteratively eliminating strictly dominated messages lead to outcomes that agree with the social choice function for all beliefs at every type profile. In an interdependent-value environment with single-crossing preferences, we identify a contraction property on the preferences which together with strict <it>ex post</it> incentive compatibility is sufficient to guarantee robust implementation in the direct mechanism. Strict <it>ex post</it> incentive compatibility and the contraction property are also necessary for robust implementation in <it>any</it> mechanism, including indirect ones. The contraction property requires that the interdependence is not too high. In a linear signal model, the contraction property is equivalent to an interdependence matrix having all eigenvalues smaller than one.