Optimal Local Transformations of Flip and Exchange Symmetric Entangled   States
  Local quantum operations relating multiqubit flip (0-1) and exchange symmetric (FES) states, with the maximum possible probability of success, have been determined by assuming that the states are converted via one-shot FES transformations. It has been shown that certain entangled states are more robust than others, in the sense that the optimum probability of converting these robust states to the states lying in the close neighborhood of separable ones vanish under local FES operations. 
G. Karpat and Z. Gedik
quant-ph