On the core of directed acyclic graph games

In this paper we consider a natural generalization of standard tree games where the underlying network is a directed acyclic graph. We briefly discuss the relation of directed acyclic graph (DAG) games with other network-based cost games. We show that in general a DAG-game is not concave, even its core might be empty, but we provide an efficiently verifiable condition satisfied by a large class of directed acyclic graphs that is sufficient for balancedness of the associated DAG-game. We introduce a network canonization process and prove various structural results for the core of canonized DAG-games, for example, we characterize classes of coalitions that have a constant payoff in the core. In addition, we identify a subset of the coalitions that is sufficient to determine the core.