Condition for tripartite entanglement
  We propose a scheme for classifying the entanglement of a tripartite pure qubit state. This classification scheme consists of an ordered list of seven elements. These elements are the Cayley hyper-determinant, and its six associated $2 \times 2$ subdeterminants. In particular we show that this classification provides a necessary and sufficient condition for separability. 
A. I. Solomon, C.-L. Ho
quant-ph math-ph math.MP