Evolution of the correlation function as traced by the HDF galaxies

An initially highly biased value of the spatial correlation function, which decreases with time up to a transition redshift z_t ~ 1-2, was predicted theoretically at least as early as 1993, and shown to be consistent with the HDF-N angular correlation function estimates in 1997. Observational analyses are presented here which show (i) an HDF-N estimate of the correlation function amplitude of galaxies selected at z ~ 2 (by the UV drop-{\em in} technique), which supports the estimate z_t ~ 2 and (ii) an HDF-N estimate of the correlation function amplitude of galaxies selected at z ~ 3.7 by using photometric redshifts, which suggests that the correlation function amplitude evolves as (1+z)^{2\pm3.5} during epochs earlier than z_t.