Extremal structure in ultrapowers of Banach spaces

Luis C. García-Lirola, Guillaume Grelier, Abraham Rueda Zoca

Given a bounded convex subset $C$ of a Banach space $X$ and a free ultrafilter $\mathcal{U}$, we study which points $(x_i{)}_{\mathcal{U}}$ are extreme points of the ultrapower $C_\mathc…