Bulletin of the Australian Mathematical Society

Research Article

Hyperconvex spaces revisited

Marcin Borkowskia1, Dariusz Bugajewskia1 and Hubert Przybycieńa1

a1 Optimisation and Control Theory Department, Faculty of Mathematics and Computer Science, Adam Mickiewicz University, Poznań, Poland, e-mail: mbork@venus.wmid.amu.edu.pl, ddbb@main.amu.edu.pl, hubert@main.amu.edu.pl

Abstract

In this paper we describe a construction of a large class of hyperconvex metric spaces. In particular, this construction contains well-known examples of hyperconvex spaces such as xs211D2 with the “river” metric or with the radial one.

Further, we investigate linear hyperconvex spaces with extremal points of their unit balls. We prove that only in the case of a plane (and obviously a line) is there a strict connection between the number of extremal points of the unit ball and the hyperconvexity of the space.

Some additional properties concerning the notion of hyperconvexity are also investigated.

(Received November 19 2003)