Cosmic Censorship Hypothesis

Informally, the cosmic censorship hypothesis for the Einstein equations asserts that singularities are always (or at least generically) concealed by black holes. Another (slightly different) version of the conjecture asserts that the maximal Cauchy development is always inextendable as a (suitably regular) Lorentzian manifold. This question is already interesting in the U(1)-symmetric case (perhaps with a matter coupling).