{"title":"Some relationships between an operator and its transform \\(S_{r}(T)\\)","authors":"Safa Menkad, Sohir Zid","doi":"10.1007/s43036-024-00317-w","DOIUrl":null,"url":null,"abstract":"<div><p>Let <span>\\( T \\in \\mathcal {B}(\\mathcal {H})\\)</span> be a bounded linear operator on a Hilbert space <span>\\( \\mathcal {H}\\)</span>, and let <span>\\( T = U \\vert T \\vert \\)</span> be the polar decomposition of <i>T</i>. For any <span>\\(r > 0\\)</span>, the transform <span>\\(S_{r}(T)\\)</span> is defined by <span>\\(S_{r}(T) = U \\vert T \\vert ^{r} U\\)</span>. In this paper, we discuss the transform <span>\\(S_{r}(T)\\)</span> of some classes of operators such as p-hyponormal and rank one operators. We provide a new characterization of invertible normal operators via this transform. Afterwards, we investigate when an operator <i>T</i> and its transform <span>\\( S_{r}(T) \\)</span> both have closed ranges, and show that this transform preserves the class of EP operators. Finally, we present some relationships between an EP operator <i>T</i>, its transform <span>\\( S_{r}(T)\\)</span> and the Moore–Penrose inverse <span>\\( T^{+} \\)</span>.</p></div>","PeriodicalId":44371,"journal":{"name":"Advances in Operator Theory","volume":"9 2","pages":""},"PeriodicalIF":0.8000,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Advances in Operator Theory","FirstCategoryId":"1085","ListUrlMain":"https://link.springer.com/article/10.1007/s43036-024-00317-w","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
Let \( T \in \mathcal {B}(\mathcal {H})\) be a bounded linear operator on a Hilbert space \( \mathcal {H}\), and let \( T = U \vert T \vert \) be the polar decomposition of T. For any \(r > 0\), the transform \(S_{r}(T)\) is defined by \(S_{r}(T) = U \vert T \vert ^{r} U\). In this paper, we discuss the transform \(S_{r}(T)\) of some classes of operators such as p-hyponormal and rank one operators. We provide a new characterization of invertible normal operators via this transform. Afterwards, we investigate when an operator T and its transform \( S_{r}(T) \) both have closed ranges, and show that this transform preserves the class of EP operators. Finally, we present some relationships between an EP operator T, its transform \( S_{r}(T)\) and the Moore–Penrose inverse \( T^{+} \).
让\( T \in \mathcal {B}(\mathcal {H})\)是希尔伯特空间\( \mathcal {H}\)上的有界线性算子,并让\( T = U \vert T \vert \)是T的极性分解。对于任意的(r >0),变换(S_{r}(T)\)的定义是(S_{r}(T) = U \vert T \vert ^{r})。U\).本文讨论了一些类算子的变换(S_{r}(T)\),如 p-hyponormal 算子和一阶算子。我们通过这个变换提供了可逆正则算子的新特征。之后,我们研究了当算子 T 及其变换 \( S_{r}(T) \) 都具有封闭范围时的情况,并证明这个变换保留了 EP 算子类。最后,我们介绍了 EP 算子 T、它的变换 \( S_{r}(T)\) 和摩尔-彭罗斯逆 \( T^{+} \) 之间的一些关系。