1 Introduce
Today, there is an increasing need for dynamic, efficient and secure sharing of resources among organizations. This is driven by a number of applications including emergency and disaster management, peace keeping, humanitarian operations, or simply virtual enterprises for commercial purposes. Typically, resource sharing is done by establishing alliances and collaborations, also known as coalitions. Due to the nature of the applications, the coalitions are often dynamic where entities may join or leave the coalition in an ad-hoc manner.