ABSTRACT
The properties of topological spaces are in general quite dierent from those of metric spaces, so some additional restrictions are often imposed on a topology in order to bring the properties of the corresponding space closer to those of metric spaces. You might have seen that distinct points or closed sets in metric spaces can be separated by open sets. In Chapter 4, we have already studied the conditions which separate distinct points by open sets. Here, we shall study the condition which separates points and closed sets.
