On Borel semifilters
  Building on work of van Engelen and van Mill, we show that a zero-dimensional Borel space is homeomorphic to a semifilter if and only if it is homogeneous and not locally compact. Under $\mathbf{\Sigma}^1_1$-Determinacy, this result extends to all analytic and coanalytic spaces. 
Andrea Medini
math.GN math.LO