  We consider vacuum solutions of four dimensional general relativity with
$\Lambda < 0$. We numerically construct stationary solutions that
asymptotically approach a boundary metric with differential rotation. Smooth
solutions only exist up to a critical rotation. We thus argue that increasing
the differential rotation by a finite amount will cause the curvature to grow
without bound. This holds for both zero and nonzero temperature, and both
compact and noncompact boundaries. However, the boundary metric always develops
an ergoregion before reaching the critical rotation, which probably means that
the energy is unbounded from below for these counterexamples to cosmic
censorship.

High Energy Physics - Theory;General Relativity and Quantum Cosmology