Foertsch, T; Lytchak, A; Schroeder, Viktor (2007). Nonpositive curvature and the Ptolemy inequality. International Mathematics Research Notices, 2007(rnm100):online.
We provide examples of nonlocally, compact, geodesic Ptolemy metric spaces which are not uniquely geodesic. On the other hand, we show that locally, compact, geodesic Ptolemy metric spaces are uniquely geodesic. Moreover, we prove that a metric space is CAT(0) if and only if it is Busemann convex and Ptolemy.
We provide examples of nonlocally, compact, geodesic Ptolemy metric spaces which are not uniquely geodesic. On the other hand, we show that locally, compact, geodesic Ptolemy metric spaces are uniquely geodesic. Moreover, we prove that a metric space is CAT(0) if and only if it is Busemann convex and Ptolemy.
| Item Type: | Journal Article, refereed, original work |
|---|---|
| Communities & Collections: | 07 Faculty of Science > Institute of Mathematics |
| Dewey Decimal Classification: | 510 Mathematics |
| Scopus Subject Areas: | Physical Sciences > General Mathematics |
| Language: | English |
| Date: | 2007 |
| Deposited On: | 10 Dec 2009 15:55 |
| Last Modified: | 03 Nov 2023 03:00 |
| Publisher: | Oxford University Press |
| ISSN: | 1073-7928 |
| Additional Information: | This is a pre-copy-editing, author-produced PDF of an article accepted for publication in International Mathematics Research Notices following peer review. The definitive publisher-authenticated version "Foertsch, T; Lytchak, A; Schroeder, V (2007). Nonpositive curvature and the Ptolemy inequality. International Mathematics Research Notices, 2007(rnm100)" is available online at: International Mathematics Research Notices |
| OA Status: | Green |
| Publisher DOI: | https://doi.org/10.1093/imrn/rnm100 |
| Related URLs: | http://arxiv.org/abs/0705.1042 |
Foertsch, T