A Note on Geodesically Bounded ℝ-Trees

It is proved that a complete geodesically bounded R-tree is the closed convex hull of the set of its extreme points. It is also noted that if X is a closed convex geodesically bounded subset of a complete R-tree Y, and if a nonexpansive mapping T:X→Y satisfies inf⁡{d(x,T(x)):x...

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Bibliographic Details
Main Author: W. A. Kirk
Format: Article
Language:English
Published: SpringerOpen 2010-01-01
Series:Fixed Point Theory and Applications
Online Access:http://dx.doi.org/10.1155/2010/393470
Description
Summary:It is proved that a complete geodesically bounded R-tree is the closed convex hull of the set of its extreme points. It is also noted that if X is a closed convex geodesically bounded subset of a complete R-tree Y, and if a nonexpansive mapping T:X→Y satisfies inf⁡{d(x,T(x)):x∈X}=0, then T has a fixed point. The latter result fails if T is only continuous.
ISSN:1687-1820
1687-1812