Classification of bi-qutrit positive partial transpose entangled edge   states by their ranks
  We construct $3\otimes 3$ PPT entangled edge states with maximal ranks, to complete the classification of $3\otimes 3$ PPT entangled edge states by their types. The ranks of the states and their partial transposes are 8 and 6, respectively. These examples also disprove claims in the literature. 
Seung-Hyeok Kye and Hiroyuki Osaka
quant-ph math.OA