Jehiel, P. and Meyer-ter-Vehn, M. and Moldovanu, B. and Zame, B. (2006) The limits of ex post implementation. (ELSE Working Papers 183). ESRC Centre for Economic Learning and Social Evolution: London, UK.
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Abstract
The sensitivity of Bayesian implementation to agents' beliefs about others suggests the use of more robust notions of implementation such as ex-post implementation, which requires that each agent' s strategy be optimal for every possible realization of the types of other agents. We show that the only deterministic social choice functions that are ex-post implementable in generic mechanism design frameworks with multi-dimensional signals, interdependent valuations and transferable utilities, are constant functions. In other words, deterministic ex-post implementation requires that the same alternative must be chosen irrespective of agents' signals. The proof shows that ex-post implementability of a non-trivial deterministic social choice function implies that certain rates of information substitution coincide for all agents. This condition amounts to a system of differential equations that are not satis ed by generic valuation functions.
| Type: | Working / discussion paper |
|---|---|
| Title: | The limits of ex post implementation |
| Open access status: | An open access version is available from UCL Discovery |
| Publisher version: | http://else.econ.ucl.ac.uk/newweb/papers.php#2006 |
| Language: | English |
| UCL classification: | UCL > School of Arts and Social Sciences > Faculty of Social and Historical Sciences > Economics |
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