Entanglement-assisted local transformations between inequivalent classes   of three-particle entangled states
  We show that bipartite and tripartite entangled states cannot be used as catalysis states to enable local transformations inbetween inequivalent classes of three-particle entangled states which are non-interchangeable under local transformations. We find the optimal protocol for conversion of a certain family of the W-states and an EPR-pair into the GHZ-state. 
Iulia Ghiu, Mohamed Bourennane, Anders Karlsson