“…This class of metric spaces in [15] covers all normed linear spaces, R-trees in the sense of Tits, the Hilbert ball with the hyperbolic metric (see [6]), Cartesian products of Hilbert balls, Hadamard manifolds (see [20]), and CAT(0) spaces in the sense of Gromov (see [4]). A thorough discussion of hyperbolic spaces and a detailed treatment of examples can be found in [15] (see also [5,6,20]). If x; y 2 X and k 2 ½0; 1; then we use the notation ð1 À kÞx È ky for Wðx; y; kÞ.…”