Fractal basins and chaotic trajectories in multi-black hole space-times
  We investigate the phase-space for trajectories in multi-black hole spacetimes. We find that complete, chaotic geodesics are well described by Lyapunov exponents, and that the attractor basin boundary scales as a fractal in a diffeomorphism invariant manner. 
N. J. Cornish, C. P. Dettmann and N. E. Frankel