  The 2D system of electron confined to the lowest Landau level is described
using a representation of the density matrix depending both on electron and
hole coordinates. Condensation of the electron system into a fractional quantum
Hall state is associated to clustering of particle and hole coordinates. The
correlation of particle and hole coordinates is studied and groundstate wave
functions are derived for $\nu=p/(2p \pm 1)$. These wave functions prove to be
accurate for the studied cases $\nu=2/3$ and $3/5$ and are identical to pair
wave functions [R. Morf et al., Phys. Rev. B34, 3037 (1986)] for $\nu=2/3$ and
$2/5$.
