Bilateral Bargaining in an Ambiguous Environment

We perturb the bilateral bargaining model by introducing small ambiguity (via the epsilon contamination model) about the agents' types. We assume that the preferences are characterized by ambiguity aversion (Gilboa-Schmeidler). The rest of the setup is exactly as in Myerson and Satterthwaite [10]. And we show that in this environment, it is possible to design a mechanism that generates almost-efficient trade. Crucially, the mechanism has to be extensive-form; standard (normal form) direct revelation mechanism can only generate outcome that is continuous with respect to the amount of ambiguity.