Efficient Full Implementation via Transfers: Uniqueness and Sensitivity in Symmetric Environments

We study efficient full implementation via transfers in unique rationalizable strategies in environments that are symmetric in two senses: first, agents display the same total level of preference interdependence; second, types are commonly known to be drawn from distributions with identical (but unknown) means. We characterize the conditions under which full efficient implementation is possible via direct mechanisms, as well as the transfer schemes that achieve it whenever possible. We discuss a further robustness property -robustness to mistaken play- and show that it uniquely selects the transfer scheme that induces an even redistribution of strategic externalities.