  We calculate the probability for rapidity gaps in the parton cascade for
different approximations within the perturbative QCD and compare the results
with recent measurements. The aim is to find out whether the dual connection
between the parton and hadron final states -- observed so far in various
inclusive measurements -- holds as well for the extreme kinematic
configurations with colour sources separated by large rapidity gaps. A
description of the data is possible indeed choosing the parameters of the
cascade in the range suggested by recent analyses of the energy spectra (the
$k_\perp$ cutoff $Q_0~\gsim$ QCD scale $\Lambda\sim 250$ MeV).
