Baillon-Bruck-Reich revisited: divergent-series parameters and strong convergence in the linear case

Fuente: arXiv
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Main Authors: Bartz, Sedi, Bauschke, Heinz H., Gao, Yuan
Format: Preprint
Published: 2025
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author Bartz, Sedi
Bauschke, Heinz H.
Gao, Yuan
author_facet Bartz, Sedi
Bauschke, Heinz H.
Gao, Yuan
contents The Krasnoselskii-Mann iteration is an important algorithm in optimization and variational analysis for finding fixed points of nonexpansive mappings. In the general case, it produces a sequence converging \emph{weakly} to a fixed point provided the parameter sequence satisfies a divergent-series condition. In this paper, we show that \emph{strong} convergence holds provided the underlying nonexpansive mapping is \emph{linear}. This improves on a celebrated result by Baillon, Bruck, and Reich from 1978, where the parameter sequence was assumed to be constant as well as on recent work where the parameters were bounded away from $0$ and $1$.
format Preprint
id arxiv_https___arxiv_org_abs_2512_22817
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Baillon-Bruck-Reich revisited: divergent-series parameters and strong convergence in the linear case
Bartz, Sedi
Bauschke, Heinz H.
Gao, Yuan
Optimization and Control
47H05, 47H09 (Primary) 47N10, 65K05, 90C25 (Secondary)
The Krasnoselskii-Mann iteration is an important algorithm in optimization and variational analysis for finding fixed points of nonexpansive mappings. In the general case, it produces a sequence converging \emph{weakly} to a fixed point provided the parameter sequence satisfies a divergent-series condition. In this paper, we show that \emph{strong} convergence holds provided the underlying nonexpansive mapping is \emph{linear}. This improves on a celebrated result by Baillon, Bruck, and Reich from 1978, where the parameter sequence was assumed to be constant as well as on recent work where the parameters were bounded away from $0$ and $1$.
title Baillon-Bruck-Reich revisited: divergent-series parameters and strong convergence in the linear case
topic Optimization and Control
47H05, 47H09 (Primary) 47N10, 65K05, 90C25 (Secondary)
url https://arxiv.org/abs/2512.22817