Dear all, I have been reading domain of dependence recently, but I don't really understand what it is all about. In Geroch and Horowitz paper, it says that the future domain of dependence is defined as the set of all points (say p) such that every past-directed time-like curve from p which cannot be assigned a past endpoint meets S, where S is an achronal slice. What does this mean? It would be nice if you can explain this to me with some examples. Does anyone know where I can read more on domain of dependence as I'm struggling to read the paper by Geroch and Horowitz. Cheers.