Some semi-Riemannian volume comparison theorems
  Lorentzian versions of classical Riemannian volume comparison theorems by Gunther, Bishop and Bishop-Gromov, are stated for suitable natural subsets of general semi-Riemannian manifolds. The problem is more subtle in the Bishop-Gromov case, which is extensively discussed. For the general semi-Riemannian case, a local version of the Gunther and Bishop theorems is given and applied. 
Paul E. Ehrlich and Miguel Sanchez (Univ. Florida, Univ. Granada)