Common Fixed Points for Asymptotic Pointwise Nonexpansive Mappings in Metric and Banach Spaces

Let C be a nonempty bounded closed convex subset of a complete CAT(0) space X. We prove that the common fixed point set of any commuting family of asymptotic pointwise nonexpansive mappings on C is nonempty closed and convex. We also show that, under some suitable conditions, the sequence {xk}k=1∞ d...

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Main Authors: P. Pasom, B. Panyanak
Format: Article
Language:English
Published: Wiley 2012-01-01
Series:Journal of Applied Mathematics
Online Access:http://dx.doi.org/10.1155/2012/327434
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author P. Pasom
B. Panyanak
author_facet P. Pasom
B. Panyanak
author_sort P. Pasom
collection DOAJ
description Let C be a nonempty bounded closed convex subset of a complete CAT(0) space X. We prove that the common fixed point set of any commuting family of asymptotic pointwise nonexpansive mappings on C is nonempty closed and convex. We also show that, under some suitable conditions, the sequence {xk}k=1∞ defined by xk+1=(1-tmk)xk⊕tmkTmnky(m-1)k, y(m-1)k=(1-t(m-1)k)xk⊕t(m-1)kTm-1nky(m-2)k,y(m-2)k=(1-t(m-2)k)xk⊕t(m-2)kTm-2nky(m-3)k,…,y2k=(1-t2k)xk⊕t2kT2nky1k,y1k=(1-t1k)xk⊕t1kT1nky0k,y0k=xk,  k∈N, converges to a common fixed point of T1,T2,…,Tm where they are asymptotic pointwise nonexpansive mappings on C, {tik}k=1∞ are sequences in [0,1] for all i=1,2,…,m, and {nk} is an increasing sequence of natural numbers. The related results for uniformly convex Banach spaces are also included.
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spelling doaj-art-30ccb7edfbe947c483bce53401506e232025-02-03T05:58:06ZengWileyJournal of Applied Mathematics1110-757X1687-00422012-01-01201210.1155/2012/327434327434Common Fixed Points for Asymptotic Pointwise Nonexpansive Mappings in Metric and Banach SpacesP. Pasom0B. Panyanak1Department of Mathematics, Faculty of Science, Chiang Mai University, Chiang Mai 50200, ThailandDepartment of Mathematics, Faculty of Science, Chiang Mai University, Chiang Mai 50200, ThailandLet C be a nonempty bounded closed convex subset of a complete CAT(0) space X. We prove that the common fixed point set of any commuting family of asymptotic pointwise nonexpansive mappings on C is nonempty closed and convex. We also show that, under some suitable conditions, the sequence {xk}k=1∞ defined by xk+1=(1-tmk)xk⊕tmkTmnky(m-1)k, y(m-1)k=(1-t(m-1)k)xk⊕t(m-1)kTm-1nky(m-2)k,y(m-2)k=(1-t(m-2)k)xk⊕t(m-2)kTm-2nky(m-3)k,…,y2k=(1-t2k)xk⊕t2kT2nky1k,y1k=(1-t1k)xk⊕t1kT1nky0k,y0k=xk,  k∈N, converges to a common fixed point of T1,T2,…,Tm where they are asymptotic pointwise nonexpansive mappings on C, {tik}k=1∞ are sequences in [0,1] for all i=1,2,…,m, and {nk} is an increasing sequence of natural numbers. The related results for uniformly convex Banach spaces are also included.http://dx.doi.org/10.1155/2012/327434
spellingShingle P. Pasom
B. Panyanak
Common Fixed Points for Asymptotic Pointwise Nonexpansive Mappings in Metric and Banach Spaces
Journal of Applied Mathematics
title Common Fixed Points for Asymptotic Pointwise Nonexpansive Mappings in Metric and Banach Spaces
title_full Common Fixed Points for Asymptotic Pointwise Nonexpansive Mappings in Metric and Banach Spaces
title_fullStr Common Fixed Points for Asymptotic Pointwise Nonexpansive Mappings in Metric and Banach Spaces
title_full_unstemmed Common Fixed Points for Asymptotic Pointwise Nonexpansive Mappings in Metric and Banach Spaces
title_short Common Fixed Points for Asymptotic Pointwise Nonexpansive Mappings in Metric and Banach Spaces
title_sort common fixed points for asymptotic pointwise nonexpansive mappings in metric and banach spaces
url http://dx.doi.org/10.1155/2012/327434
work_keys_str_mv AT ppasom commonfixedpointsforasymptoticpointwisenonexpansivemappingsinmetricandbanachspaces
AT bpanyanak commonfixedpointsforasymptoticpointwisenonexpansivemappingsinmetricandbanachspaces