We discuss an integer programming formulation for a class of cooperative ga
mes. We focus on algorithmic aspects of the core, one of the most important
solution concepts in cooperative game theory. Central to our study is a si
mple (but very useful) observation that the core for this class is nonempty
if and only if an associated linear program has an integer optimal solutio
n. Based on this, we study the computational complexity and algorithms to a
nswer important questions about the cores of various games on graphs, such
as maximum flow, connectivity, maximum matching, minimum vertex cover, mini
mum edge cover, maximum independent set, and minimum coloring.