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: W. A. Kirk, B. Panyanak
Format: Journal
Published: 2018
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http://cmuir.cmu.ac.th/jspui/handle/6653943832/60987
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Institution: Chiang Mai University
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spelling th-cmuir.6653943832-609872018-09-10T04:06:51Z Best approximation in ℝ-trees W. A. Kirk B. Panyanak Computer Science Mathematics 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. 2018-09-10T04:02:28Z 2018-09-10T04:02:28Z 2007-05-01 Journal 15322467 01630563 2-s2.0-34249098113 10.1080/01630560701348517 https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=34249098113&origin=inward http://cmuir.cmu.ac.th/jspui/handle/6653943832/60987
institution Chiang Mai University
building Chiang Mai University Library
country Thailand
collection CMU Intellectual Repository
topic Computer Science
Mathematics
spellingShingle Computer Science
Mathematics
W. A. Kirk
B. Panyanak
Best approximation in ℝ-trees
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 Journal
author W. A. Kirk
B. Panyanak
author_facet W. A. Kirk
B. Panyanak
author_sort W. A. Kirk
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 2018
url https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=34249098113&origin=inward
http://cmuir.cmu.ac.th/jspui/handle/6653943832/60987
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