  We present predictions for numerous statistics related to the presence of
voids in the distribution of galaxies in a cold dark matter model of structure
formation using a semi-analytic model of galaxy formation. Our study is able to
probe galaxies with masses as low as 10^9Msun/h corresponding to absolute
magnitudes of M_bJ-5log(h)=-18.1 and M_r-5log(h)=-18.7. We quantify the void
and underdense probability functions, distributions of nearest neighbour
distances and void sizes and compute the density profiles of voids. These
results are contrasted with the expectations for dark matter (and the
difference examined in terms of the galaxy/dark matter biasing relation) and
are compared to analytic predictions and observational data where available.
The predicted void probability functions are consistent with those measured
from the Center for Astrophysics redshift surveys given the rather large
uncertainties in this relatively small (for studies of voids) observational
sample. The size of the observational sample is too small to probe the bias
between galaxies and dark matter that we predict. We also examine the predicted
properties of galaxies living within voids and contrast these with the general
galaxy population. Our predictions are aimed at forthcoming large galaxy
redshift surveys which should for the first time provide statistically accurate
measures of the void population.
