  We discuss the space-time picture of scattering amplitudes with single and
double ladder exchange in perturbative QCD. Particular emphasis is given to the
Abramovsky Gribov Kanchelli (AGK) rules which describe the relative
contributions of the diffractive dissociation and processes with other
multiplicities to the elastic scattering amplitude. Inside the Pomeron Pomeron
interaction vertices we find a new matrix which describes the transition from
one s-cut to another and which goes beyond the original the AGK rules.
