{"title":"超常可测算子,隶属于半有限冯-诺依曼代数","authors":"Airat Bikchentaev","doi":"10.1007/s43036-024-00388-9","DOIUrl":null,"url":null,"abstract":"<div><p>Let <span>\\(\\mathcal {M}\\)</span> be a von Neumann algebra of operators on a Hilbert space <span>\\(\\mathcal {H}\\)</span> and <span>\\(\\tau \\)</span> be a faithful normal semifinite trace on <span>\\(\\mathcal {M}\\)</span>, <span>\\(S(\\mathcal {M}, \\tau )\\)</span> be the <span>\\( ^*\\)</span>-algebra of all <span>\\(\\tau \\)</span>-measurable operators. Assume that an operator <span>\\(T\\in S(\\mathcal {M}, \\tau )\\)</span> is paranormal or <span>\\( ^*\\)</span>-paranormal. If <span>\\(T^n\\)</span> is <span>\\(\\tau \\)</span>-compact for some <span>\\(n\\in \\mathbb {N}\\)</span> then <i>T</i> is <span>\\(\\tau \\)</span>-compact; if <span>\\(T^n=0\\)</span> for some <span>\\(n\\in \\mathbb {N}\\)</span> then <span>\\(T=0\\)</span>; if <span>\\(T^3=T\\)</span> then <span>\\(T=T^*\\)</span>; if <span>\\(T^2\\in L_1(\\mathcal {M}, \\tau )\\)</span> then <span>\\(T\\in L_2(\\mathcal {M}, \\tau )\\)</span> and <span>\\(\\Vert T\\Vert _2^2=\\Vert T^2\\Vert _1\\)</span>. If an operator <span>\\(T\\in S(\\mathcal {M}, \\tau )\\)</span> is hyponormal and <span>\\(T^{*p}T^q\\)</span> is <span>\\(\\tau \\)</span>-compact for some <span>\\(p, q \\in \\mathbb {N}\\cup \\{0\\}\\)</span>, <span>\\(p+q \\ge 1\\)</span> then <i>T</i> is normal. If <span>\\(T\\in S(\\mathcal {M}, \\tau )\\)</span> is <i>p</i>-hyponormal for some <span>\\(0<p\\le 1\\)</span> then the operator <span>\\((T^*T)^p-(TT^*)^p\\)</span> cannot have the inverse in <span>\\( \\mathcal {M}\\)</span>. If an operator <span>\\(T\\in S(\\mathcal {M}, \\tau )\\)</span> is hyponormal (or cohyponormal) and the operator <span>\\(T^2\\)</span> is Hermitian then <i>T</i> is normal.</p></div>","PeriodicalId":44371,"journal":{"name":"Advances in Operator Theory","volume":"9 4","pages":""},"PeriodicalIF":0.8000,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Hyponormal measurable operators, affiliated to a semifinite von Neumann algebra\",\"authors\":\"Airat Bikchentaev\",\"doi\":\"10.1007/s43036-024-00388-9\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Let <span>\\\\(\\\\mathcal {M}\\\\)</span> be a von Neumann algebra of operators on a Hilbert space <span>\\\\(\\\\mathcal {H}\\\\)</span> and <span>\\\\(\\\\tau \\\\)</span> be a faithful normal semifinite trace on <span>\\\\(\\\\mathcal {M}\\\\)</span>, <span>\\\\(S(\\\\mathcal {M}, \\\\tau )\\\\)</span> be the <span>\\\\( ^*\\\\)</span>-algebra of all <span>\\\\(\\\\tau \\\\)</span>-measurable operators. Assume that an operator <span>\\\\(T\\\\in S(\\\\mathcal {M}, \\\\tau )\\\\)</span> is paranormal or <span>\\\\( ^*\\\\)</span>-paranormal. If <span>\\\\(T^n\\\\)</span> is <span>\\\\(\\\\tau \\\\)</span>-compact for some <span>\\\\(n\\\\in \\\\mathbb {N}\\\\)</span> then <i>T</i> is <span>\\\\(\\\\tau \\\\)</span>-compact; if <span>\\\\(T^n=0\\\\)</span> for some <span>\\\\(n\\\\in \\\\mathbb {N}\\\\)</span> then <span>\\\\(T=0\\\\)</span>; if <span>\\\\(T^3=T\\\\)</span> then <span>\\\\(T=T^*\\\\)</span>; if <span>\\\\(T^2\\\\in L_1(\\\\mathcal {M}, \\\\tau )\\\\)</span> then <span>\\\\(T\\\\in L_2(\\\\mathcal {M}, \\\\tau )\\\\)</span> and <span>\\\\(\\\\Vert T\\\\Vert _2^2=\\\\Vert T^2\\\\Vert _1\\\\)</span>. If an operator <span>\\\\(T\\\\in S(\\\\mathcal {M}, \\\\tau )\\\\)</span> is hyponormal and <span>\\\\(T^{*p}T^q\\\\)</span> is <span>\\\\(\\\\tau \\\\)</span>-compact for some <span>\\\\(p, q \\\\in \\\\mathbb {N}\\\\cup \\\\{0\\\\}\\\\)</span>, <span>\\\\(p+q \\\\ge 1\\\\)</span> then <i>T</i> is normal. If <span>\\\\(T\\\\in S(\\\\mathcal {M}, \\\\tau )\\\\)</span> is <i>p</i>-hyponormal for some <span>\\\\(0<p\\\\le 1\\\\)</span> then the operator <span>\\\\((T^*T)^p-(TT^*)^p\\\\)</span> cannot have the inverse in <span>\\\\( \\\\mathcal {M}\\\\)</span>. If an operator <span>\\\\(T\\\\in S(\\\\mathcal {M}, \\\\tau )\\\\)</span> is hyponormal (or cohyponormal) and the operator <span>\\\\(T^2\\\\)</span> is Hermitian then <i>T</i> is normal.</p></div>\",\"PeriodicalId\":44371,\"journal\":{\"name\":\"Advances in Operator Theory\",\"volume\":\"9 4\",\"pages\":\"\"},\"PeriodicalIF\":0.8000,\"publicationDate\":\"2024-10-07\",\"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/s43036-024-00388-9\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Advances in Operator Theory","FirstCategoryId":"1085","ListUrlMain":"https://link.springer.com/article/10.1007/s43036-024-00388-9","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
Hyponormal measurable operators, affiliated to a semifinite von Neumann algebra
Let \(\mathcal {M}\) be a von Neumann algebra of operators on a Hilbert space \(\mathcal {H}\) and \(\tau \) be a faithful normal semifinite trace on \(\mathcal {M}\), \(S(\mathcal {M}, \tau )\) be the \( ^*\)-algebra of all \(\tau \)-measurable operators. Assume that an operator \(T\in S(\mathcal {M}, \tau )\) is paranormal or \( ^*\)-paranormal. If \(T^n\) is \(\tau \)-compact for some \(n\in \mathbb {N}\) then T is \(\tau \)-compact; if \(T^n=0\) for some \(n\in \mathbb {N}\) then \(T=0\); if \(T^3=T\) then \(T=T^*\); if \(T^2\in L_1(\mathcal {M}, \tau )\) then \(T\in L_2(\mathcal {M}, \tau )\) and \(\Vert T\Vert _2^2=\Vert T^2\Vert _1\). If an operator \(T\in S(\mathcal {M}, \tau )\) is hyponormal and \(T^{*p}T^q\) is \(\tau \)-compact for some \(p, q \in \mathbb {N}\cup \{0\}\), \(p+q \ge 1\) then T is normal. If \(T\in S(\mathcal {M}, \tau )\) is p-hyponormal for some \(0<p\le 1\) then the operator \((T^*T)^p-(TT^*)^p\) cannot have the inverse in \( \mathcal {M}\). If an operator \(T\in S(\mathcal {M}, \tau )\) is hyponormal (or cohyponormal) and the operator \(T^2\) is Hermitian then T is normal.