Partially-honest Nash implementation: a full characterization

Abstract

A partially-honest individual is a person who follows the maxim, “Do not lie if you do not have to”, to serve your material interest. By assuming that the mechanism designer knows that there is at least one partially-honest individual in a society of $$ n\ge 3$$ n ≥ 3 individuals, a social choice rule that can be Nash implemented is termed partially-honestly Nash implementable. The paper offers a complete characterization of the (unanimous) social choice rules that are partially-honestly Nash implementable. When all individuals are partially-honest, then any (unanimous) rule is partially-honestly Nash implementable. An account of the welfare implications of partially-honest Nash implementation is provided in a variety of environments.

Implementation with a sympathizer

“…Our main result and its first robustness check are in Section 4. Section C of the Appendix 6 An incomplete list of papers in this literature consists of Matsushima (2008a), Matsushima (2008b), Kartik and Tercieux (2012), Kartik, Tercieux, and Holden (2014), Korpela (2014), Saporiti (2014), Ortner (2015), Dogan (2017), Kimya (2017), Lombardi and Yoshihara (2017), Mukherjee, Muto, and Ramaekers (2017), Lombardi and Yoshihara (2018), Savva (2018), and Lombardi and Yoshihara (2019). See also Dutta (2019) for a survey of recent results in this literature.…”