Open AccessUniform Asymptotic Regularity for Mann Iterates
Author(s) -
Ulrich Kohlenbach
Publication year - 2002
Publication title -
brics report series
Language(s) - English
Resource type - Journals
eISSN - 1601-5355
pISSN - 0909-0878
DOI - 10.7146/brics.v9i10.21728
Subject(s) - mathematics , bounded function , iterated function , extension (predicate logic) , regular polygon , uniform boundedness , discrete mathematics , uniform continuity , pure mathematics , fixed point , fixed point theorem , mathematical analysis , computer science , metric space , geometry , programming language
In a previous paper we obtained an effective quantitative analysis of a theorem due to Borwein, Reich and Shafrir on the asymptotic behavior of general Krasnoselski-Mann iterations for nonexpansive self-mappings of convex sets C in arbitrary normed spaces. We used this result to obtain a new strong uniform version of Ishikawa's theorem for bounded C . In this paper we give a qualitative improvement of our result in the unbounded case and prove the uniformity result for the bounded case under the weaker assumption that C contains a point x whose Krasnoselski-Mann iteration (x_n) is bounded. We also consider more general iterations for which asymptotic regularity is known only for uniformly convex spaces (Groetsch). We give uniform effective bounds for (an extension of) Groetsch's theorem which generalize previous results by Kirk/Martinez-Yanez and the author.