  We consider one copy of a quantum system prepared with equal prior
probability in one of two non-orthogonal entangled states of multipartite
distributed among separated parties. We demonstrate that these two states can
be optimally distinguished in the sense of conclusive discrimination by local
operations and classical communications(LOCC) alone. And this proves strictly
the conjecture that Virmani et.al. [8] confirmed numerically and analytically.
Generally, the optimal protocol requires local POVM operations which are
explicitly constructed. The result manifests that the distinguishable
information is obtained only and completely at the last operation and all prior
ones give no information about that state.
