The Void Phenomenon Revisited
  The Void Phenomenon consists in the apparent discrepancy between the number
of observed dwarf halos in cosmic voids and that expected from CDM simulations.
We approach the problem considering the challenging prospects of detecting
field dwarf systems with halo masses < 10^9 solar, via their possible HI
emission. A brief review of recent work is followed by preliminary results from
the ALFALFA survey, which suggest the possibility, but not yet the proof, that
such objects may have been already detected towards the outskirts of the Local
Group.
