Seeking for toroidal event horizons from initially stationary BH
  configurations
  We construct and evolve non-rotating vacuum initial data with a ring
singularity, based on a simple extension of the standard Brill-Lindquist
multiple black-hole initial data, and search for event horizons with spatial
slices that are toroidal when the ring radius is sufficiently large. While
evolutions of the ring singularity are not numerically feasible for large
radii, we find some evidence, based on configurations of multiple BHs arranged
in a ring, that this configuration leads to singular limit where the horizon
width has zero size, possibly indicating the presence of a naked singularity,
when the radius of the ring is sufficiently large. This is in agreement with
previous studies that have found that there is no apparent horizon surrounding
the ring singularity when the ring's radius is larger than about twice its
mass.
