Entanglement and kinds of pure three-qubit states

Aiming at pure three-qubit states, the concept of distributed entanglement and the corresponding measure called tangle are discussed, the expressions and the inherent relations among the tangles are proposed. Analyzed the kinds of pure three-qubit states with the tangles τAB, τAC, τBC and τABC it is found that at least seven kinds of distributed entanglements exist for the states, but not six kinds as in Martin P and Vladimir B's conclusion. A criterion for product and entangled states is provided simultaneously.