Ball separation properties in Banach spaces
George Washington Univeristy, U.S.A.
It is a well known fact that a point outside a closed bounded convex set can be separated by the latter by a hyperpalne. One can ask whether the separation can be done by intersection of balls. This is typical example of a ball separation property the study of which has become important in geometry of Banach spaces. Here, we talk about some such properties and their relation to each other. We also look at some stability results of these properties.