  We discuss the phenomenology of the superconductivity resulting from the bose
condensation of the preformed pairs coexisting with unpaired fermions. We show
that this transition is more mean field like than usual bose condensation, i.e.
it is characterized by a relatively small value of the Ginzburg parameter. We
consider the Hall effect in the vortex flow regime and in the fluctuational
regime above $T_c$ and show that in this situation it is much less than in the
transition driven entirely by bose condesation but much larger than in a usual
superconductivity. We analyse the available Hall data and conclude that this
phenomenology describes reasonably well the data in the underdoped materials of
$YBaCuO$ family but is not an appropriate description of optimally doped
materials or underdoped $LaSrCuO$.
