Hedonic Expertise Games

We consider a team formation setting where agents have varying levels of expertise in a global set of required skills, and teams are ranked with respect to how well the expertise of teammates complement each other. We model this setting as a hedonic game, and we show that this class of games possesses many desirable properties, some of which are as follows: A partition that is Nash stable, core stable and Pareto optimal is always guaranteed to exist. A contractually individually stable partition (and a Nash stable partition in a restricted setting) can be found in polynomial-time. A core stable partition can be approximated within a factor of 1 - 1/e and this bound is tight. We discover a larger and relatively general class of hedonic games, where the above existence guarantee holds. For this larger class, we present simple dynamics that converge to a Nash stable partition in a relatively low number of moves.