Subgame-Perfect Implementation Under Information Perturbations*
研究了扩展式机制在自然状态非共同知识（信息扰动）下的稳健性，发现即使微小扰动也会导致Moore-Repullo机制无法实现真实披露，且任何非Maskin单调的社会目标都存在不良均衡，最后指出外部选项可改善效率。
Abstract We consider the robustness of extensive form mechanisms to deviations from common knowledge about the state of nature, which we refer to as information perturbations . First, we show that even under arbitrarily small information perturbations the Moore-Repullo mechanism does not yield (even approximately) truthful revelation and that in addition the mechanism has sequential equilibria with undesirable outcomes. More generally, we prove that any extensive form mechanism is fragile in the sense that if a non-Maskin monotonic social objective can be implemented with this mechanism, then there are arbitrarily small information perturbations under which an undesirable sequential equilibrium also exists. Finally, we argue that outside options can help improve efficiency in asymmetric information environments, and that these options can be thought of as reflecting ownership of an asset.