Fixed point property of direct sums

For a uniformly convex space Z, we show that Z-direct sums (X1⊕⋯⊕XN)Z of Banach spaces X1,...,XN with R(a,Xi)<1+a for some a ∈(0,1] have the fixed point property for nonexpansive mappings. As a direct consequence, the result holds for all ψ-direct sums with ψ being strictly convex. The same resul...

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Bibliographic Details
Main Authors: Dhompongsa S., Kaewcharoen A., Kaewkhao A.
Format: Conference or Workshop Item
Language:English
Published: 2014
Online Access:http://www.scopus.com/inward/record.url?eid=2-s2.0-28044438707&partnerID=40&md5=c24707ee3c75db04bfaffdc7706a32f1
http://cmuir.cmu.ac.th/handle/6653943832/4924
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Institution: Chiang Mai University
Language: English
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Summary:For a uniformly convex space Z, we show that Z-direct sums (X1⊕⋯⊕XN)Z of Banach spaces X1,...,XN with R(a,Xi)<1+a for some a ∈(0,1] have the fixed point property for nonexpansive mappings. As a direct consequence, the result holds for all ψ-direct sums with ψ being strictly convex. The same result is extended to all ψ-direct sums X⊕ψY of spaces X and Y with property (M), whenever ψ≠ψ1. The permanence of properties that are sufficient for the fixed point property are obtained for Z-direct sums (and then for ψ-direct sums). Such properties include the properties R(X)<2, WNUS, CNJ(a,X)<2, UKK, and NUC. © 2005 Elsevier Ltd. All rights reserved.