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.