Lower Bound of Multipartite Concurrence Based on Sub-quantum State   Decomposition
  We study the entanglement of tripartite quantum states and provide analytical lower bound of concurrence in terms of the concurrence of sub-states. The lower bound may improve all the existing lower bounds of concurrence. The approach is generalized to arbitrary dimensional multipartite systems. 
Xue-Na Zhu, Ming-Jing Zhao and Shao-Ming Fei
quant-ph