Reaching Consensus Through Simultaneous Bargaining

We propose a two-player bargaining game where each player simultaneously proposes a set of lotteries on a finite set of alternatives. If the two sets have elements in common the outcome is selected by the uniform probability measure over the intersection. If otherwise the sets do not intersect the outcome is selected by the uniform probability measure over the union. We show that this game always has an equilibrium in sincere strategies (i.e. such that players truthfully reveal their preferences). We also prove that every equilibrium is individually rational and consensual. If furthermore players are partially honest then every equilibrium is efficient and sincere. We use this result to fully characterize the set of equilibria of the game under partial honesty.