  Motivated by data on coauthorships in scientific publications, we analyze a
team formation process that generalizes matching models and network formation
models, allowing for overlapping teams of heterogeneous size. We apply
different notions of stability: myopic team-wise stability, which extends to
our setup the concept of pair-wise stability, coalitional stability, where
agents are perfectly rational and able to coordinate, and stochastic stability,
where agents are myopic and errors occur with vanishing probability. We find
that, in many cases, coalitional stability in no way refines myopic team-wise
stability, while stochastically stable states are feasible states that maximize
the overall number of activities performed by teams.
