We explore the consequences of weakening the notion of incentive compatibility from strategy-proofness to ordinal Bayesian incentive compatibility (OBIC) in the random assignment model. If the common prior of the agents is a uniform prior, then a large class of random mechanisms are OBIC with respect to this prior -- this includes the probabilistic serial mechanism. We then introduce a robust version of OBIC: a mechanism is locally robust OBIC if it is OBIC with respect all independent priors in some neighborhood of a given independent prior. We show that every locally robust OBIC mechanism satisfying a mild property called elementary monotonicity is strategy-proof. This leads to a strengthening of the impossibility result in Bogomolnaia and Moulin (2001): if there are at least four agents, there is no locally robust OBIC and ordinally efficient mechanism satisfying equal treatment of equals.
翻译:我们探讨在随机派任模式中,激励性兼容性概念从战略防守性到随机派任模式(OBIC)对正常巴伊西亚州激励性兼容性(OBIC)的削弱后果。如果在代理人之前的通常做法是统一的,那么大量的随机机制是先前的OBIC(OBIC),这包括概率序列机制。然后,我们引入一个稳健的OBIC(OBIC):如果该机制是地方稳健的OBIC(OBIC)机制,尊重先前某个独立社区的所有独立前科。我们表明,每个地方稳健的OBIC(OBIC)机制,只要满足被称为初级单体的温度地产,即具有战略防守性。这导致Bogoomolnaa和Moulin(2001年)的不可能结果的加强:如果至少有四个代理人,则没有地方稳健的OBIC(OBIC)和(或非常有效的机制,能满足同等待遇。