750 deg$^2$ at a limiting magnitude of 20.85 in the $B_J$ band. The completely identified sample (not yet released) consists of nearly 22,500 QSOs in the redshift range $0.3\le z\le 2.2$. The results from the preliminary data release (to be considered with some caution), expressed in terms of the correlation function integrated inside spheres of $20h^{-1} $ Mpc, $\bar{\xi}(20)$, are shown in Fig. \[conserving\], together with the estimates obtained at $z\sim 0.1$ for the AERQS sample. The discussion of the theoretical models shown by the different lines, will be given in the following Section.

For an EdS universe (left panels), @2qzclust find that there is no significant evolution of the QSO clustering in comoving coordinates over the whole redshift range considered. Assuming a $\Lambda$ model (right panels), the clustering shows a marginal increase at high redshifts, with a minimum of $\xi(r)$ near $z\sim 0.5-1.0$. Our data show a tendency to an increase of $\bar{\xi}(20)$ at low-$z$, both for the EdS and $\Lambda$ models. This result supports the predictions based on simple theoretical models (see next section) and on numerical simulations by @bagla98a. Notice that very recently this general trend for the clustering evolution has been also confirmed by the power 