Tight multipartite Bell's inequalities involving many measurement   settings
  We derive tight Bell's inequalities for N>2 observers involving more than two alternative measurement settings. We give a necessary and sufficient condition for a general quantum state to violate the new inequalities. The inequalities are violated by some classes of states, for which all standard Bell's inequalities with two measurement settings per observer are satisfied. 
Wieslaw Laskowski, Tomasz Paterek, Marek Zukowski, Caslav Brukner