Best approximation in ℝ-trees

An ℝ-tree is a geodesic space for which there is a unique arc joining any two of its points, and this arc is a metric segment. We give a constructive proof of the following "best approximation" theorem in such spaces. Suppose X is a closed convex and geodesically bounded subset of an ℝ-tre...

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Main Authors: Kirk W.A., Panyanak B.
Format: Article
Language:English
Published: 2014
Online Access:http://www.scopus.com/inward/record.url?eid=2-s2.0-34249098113&partnerID=40&md5=fa3d6f01b2140fd5433b5e8adf14463d
http://cmuir.cmu.ac.th/handle/6653943832/5265
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Institution: Chiang Mai University
Language: English
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spelling th-cmuir.6653943832-52652014-08-30T02:56:20Z Best approximation in ℝ-trees Kirk W.A. Panyanak B. An ℝ-tree is a geodesic space for which there is a unique arc joining any two of its points, and this arc is a metric segment. We give a constructive proof of the following "best approximation" theorem in such spaces. Suppose X is a closed convex and geodesically bounded subset of an ℝ-tree H, and suppose T:X2H is a multivalued upper semicontinuous mapping whose values are nonempty closed convex subsets of X. Then there exists a point x0X such that [image omitted] We also give a topological version of the above theorem in a more abstract setting, and we prove a KKM theorem for geodesically bounded ℝ-trees. 2014-08-30T02:56:20Z 2014-08-30T02:56:20Z 2007 Article 01630563 10.1080/01630560701348517 NFAOD http://www.scopus.com/inward/record.url?eid=2-s2.0-34249098113&partnerID=40&md5=fa3d6f01b2140fd5433b5e8adf14463d http://cmuir.cmu.ac.th/handle/6653943832/5265 English
institution Chiang Mai University
building Chiang Mai University Library
country Thailand
collection CMU Intellectual Repository
language English
description An ℝ-tree is a geodesic space for which there is a unique arc joining any two of its points, and this arc is a metric segment. We give a constructive proof of the following "best approximation" theorem in such spaces. Suppose X is a closed convex and geodesically bounded subset of an ℝ-tree H, and suppose T:X2H is a multivalued upper semicontinuous mapping whose values are nonempty closed convex subsets of X. Then there exists a point x0X such that [image omitted] We also give a topological version of the above theorem in a more abstract setting, and we prove a KKM theorem for geodesically bounded ℝ-trees.
format Article
author Kirk W.A.
Panyanak B.
spellingShingle Kirk W.A.
Panyanak B.
Best approximation in ℝ-trees
author_facet Kirk W.A.
Panyanak B.
author_sort Kirk W.A.
title Best approximation in ℝ-trees
title_short Best approximation in ℝ-trees
title_full Best approximation in ℝ-trees
title_fullStr Best approximation in ℝ-trees
title_full_unstemmed Best approximation in ℝ-trees
title_sort best approximation in ℝ-trees
publishDate 2014
url http://www.scopus.com/inward/record.url?eid=2-s2.0-34249098113&partnerID=40&md5=fa3d6f01b2140fd5433b5e8adf14463d
http://cmuir.cmu.ac.th/handle/6653943832/5265
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