We argue that a new solution concept by Huang and Sjöström (2002),
called the r-core, extends the concept of core to games in partition function
forms naturally. Moreover, the r-core can be implemented by a modi…ed
Perry and Reny (1994) game in a straightforward manner. We show that:
1) every stationary subgame perfect Nash equilibrium (SSPNE) outcome
must be in the r-core; 2) with the additional assumption of superadditivity,
every r-core can be implemented as an SSPNE.
