The Cauchy Horizon in Higher-derivative Gravity Theories
  A class of exact solutions of the field equations with higher derivative terms is presented when the matter field is a pressureless null fluid plus a Maxwellian static electric component. It is found that the stable solutions are black holes in anti de Sitter background. The issue of the stability of the Cauchy horizon is discussed. 
Alfio Bonanno (Istituto di Astronomia, Catania)