Generalization of the entanglement of formation for multi-party systems

We present the generalization of the entanglement of formation for three-party systems in a pure state. For three qubit system we derive out its explicit and closed expression which is a linear combination of the binary entropy functions with various arguments, and these arguments are clearly determined in terms of the components of state vector of three qubits. As a reasonable measure of entanglement, the main behaviors and elementary properties of this generalized entanglement of formation are showed through discussing some important and interesting examples. Moreover, we propose how to extend our definition to a mixed state in according to the familiar idea. Then, we suggest the generalization of the entanglement of formation for multi-party systems which is consistent with the regular definition for two-party systems and our definition for three-party systems.