A social choice rule (SCR) $F$ maps preference profiles to lotteries over some finite set of outcomes. $F$ is virtually implementable in (pure and mixed) Nash equilibria provided that for all $\epsilon 0$, there exists a mechanism such that for each preference profile $\theta$, its set of Nash...

We study the relationship between two-agent implementation problems and the notionof interim efficiency due to Holmström and Myerson (1983) in Bayesian environmentswith private values and independent types. We present a general property, Bayesianefficiency, and show that it is sufficient for...