Comments on 4-point functions in the CFT/AdS correspondence
  We study the four--point function of chiral primaries corresponding to the dilaton--axion sector in supergravity in the $AdS_5$/CFT$_4$ correspondence. We find relations between some of the supergravity graphs and compute their leading singularities. We discuss the issue of logarithmic singularities and their significance for the OPE structure of the CFT. 
Daniel Z. Freedman, Samir D. Mathur, Alec Matusis and Leonardo   Rastelli