A Generalized Block-Iterative Projection Method for the Common Fixed Point Problem Induced by Cutters

Fuente: arXiv
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Auteurs principaux: Censor, Yair, Reem, Daniel, Zaknoon, Maroun
Format: Preprint
Publié: 2022
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author Censor, Yair
Reem, Daniel
Zaknoon, Maroun
author_facet Censor, Yair
Reem, Daniel
Zaknoon, Maroun
contents The block-iterative projections (BIP) method of Aharoni and Censor [Block-iterative projection methods for parallel computation of solutions to convex feasibility problems, Linear Algebra and its Applications 120, (1989), 165--175] is an iterative process for finding asymptotically a point in the nonempty intersection of a family of closed convex subsets. It employs orthogonal projections onto the individual subsets in an algorithmic regime that uses "blocks" of operators and has great flexibility in constructing specific algorithms from it. We extend this algorithmic scheme to handle a family of continuous cutter operators and to find a common fixed point of them. Since the family of continuous cutters includes several important specific operators, our generalized scheme, which ensures global convergence and retains the flexibility of BIP, can handle, in particular, metric (orthogonal) projectors and continuous subgradient projections, which are very important in applications. We also allow a certain kind of adaptive perturbations to be included, and along the way we derive a perturbed Fejér monotonicity lemma which is of independent interest.
format Preprint
id arxiv_https___arxiv_org_abs_2204_09770
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle A Generalized Block-Iterative Projection Method for the Common Fixed Point Problem Induced by Cutters
Censor, Yair
Reem, Daniel
Zaknoon, Maroun
Optimization and Control
Functional Analysis
47H10, 90C31, 49K40, 90C30, 90C59
G.1.6; G.1.2; F.2.1
The block-iterative projections (BIP) method of Aharoni and Censor [Block-iterative projection methods for parallel computation of solutions to convex feasibility problems, Linear Algebra and its Applications 120, (1989), 165--175] is an iterative process for finding asymptotically a point in the nonempty intersection of a family of closed convex subsets. It employs orthogonal projections onto the individual subsets in an algorithmic regime that uses "blocks" of operators and has great flexibility in constructing specific algorithms from it. We extend this algorithmic scheme to handle a family of continuous cutter operators and to find a common fixed point of them. Since the family of continuous cutters includes several important specific operators, our generalized scheme, which ensures global convergence and retains the flexibility of BIP, can handle, in particular, metric (orthogonal) projectors and continuous subgradient projections, which are very important in applications. We also allow a certain kind of adaptive perturbations to be included, and along the way we derive a perturbed Fejér monotonicity lemma which is of independent interest.
title A Generalized Block-Iterative Projection Method for the Common Fixed Point Problem Induced by Cutters
topic Optimization and Control
Functional Analysis
47H10, 90C31, 49K40, 90C30, 90C59
G.1.6; G.1.2; F.2.1
url https://arxiv.org/abs/2204.09770