R Function Related to Entanglement of Formation
  By investigating the convex property of the function R, appeared in computing the entanglement of formation for isotropic states in Phys. Rev. Lett. 85, 2625 (2000), and a tight lower bound of entanglement of formation for arbitrary bipartite mixed states in Phys. Rev. Lett. 95, 210501 (2005), we show analytically that the very nice results in these papers are valid not only for dimensions 2 and 3 but any dimensions. 
Shao-Ming Fei, Xianqing Li-Jost