An entity is a nested member of a first group if that entity is a member of a second group and the second group is a member of the first group....http://www.google.cl/patents/US7363339?utm_source=gb-gplus-sharePatent US7363339 - Determining group membershipAdvanced Patent SearchPublication numberUS7363339 B2Publication typeGrantApplication numberUS 09/998,926Publication date22 Apr 2008Filing date3