{"title":"The Kaczmarz Algorithm in Hilbert C∗-modules","authors":"Daniel Alpay , Chad Berner , Eric S. Weber","doi":"10.1016/j.exmath.2025.125738","DOIUrl":null,"url":null,"abstract":"<div><div>The Kaczmarz algorithm in Hilbert spaces is a classical iterative method for stably recovering vectors from inner product data. In this paper, we extend the algorithm to the setting of Hilbert <span><math><msup><mrow><mi>C</mi></mrow><mrow><mo>∗</mo></mrow></msup></math></span>-modules and establish analogues of its effectiveness in both finite-dimensional and stationary cases. Consequently, we demonstrate that continuous families of elements in a Hilbert space can be uniformly recovered using the Kaczmarz algorithm. Additionally, we develop a normalized Cauchy transform for continuous families of measures and use it to provide sufficient conditions under which standard frames in Hilbert <span><math><mrow><mi>C</mi><mrow><mo>(</mo><mi>X</mi><mo>)</mo></mrow></mrow></math></span>-modules can be generated by the Kaczmarz algorithm and realized as orbits of bounded operators.</div></div>","PeriodicalId":50458,"journal":{"name":"Expositiones Mathematicae","volume":"44 2","pages":"Article 125738"},"PeriodicalIF":0.8000,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Expositiones Mathematicae","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0723086925000933","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/11/25 0:00:00","PubModel":"Epub","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
The Kaczmarz algorithm in Hilbert spaces is a classical iterative method for stably recovering vectors from inner product data. In this paper, we extend the algorithm to the setting of Hilbert -modules and establish analogues of its effectiveness in both finite-dimensional and stationary cases. Consequently, we demonstrate that continuous families of elements in a Hilbert space can be uniformly recovered using the Kaczmarz algorithm. Additionally, we develop a normalized Cauchy transform for continuous families of measures and use it to provide sufficient conditions under which standard frames in Hilbert -modules can be generated by the Kaczmarz algorithm and realized as orbits of bounded operators.
Hilbert空间中的Kaczmarz算法是一种从内积数据中稳定恢复向量的经典迭代方法。在本文中,我们将该算法推广到Hilbert C * -模的集合,并建立了它在有限维和平稳情况下的有效性的类比。因此,我们证明了Hilbert空间中的连续族元素可以用Kaczmarz算法一致恢复。此外,我们开发了连续测度族的规范化Cauchy变换,并利用它提供了Hilbert C(X)-模块中的标准帧可以由Kaczmarz算法生成并实现为有界算子的轨道的充分条件。
期刊介绍:
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