{"title":"C^*-代数包含的归一化器和近似单位","authors":"David R. Pitts","doi":"10.1512/iumj.2023.72.9539","DOIUrl":null,"url":null,"abstract":"For an inclusion of C*-algebras $D\\subseteq A$ with $D$ abelian, we show that when $n\\in A$ normalizes $D$, $n^*n$ and $nn^*$ commute with $D$. As a corollary, when $D$ is a regular MASA in $A$, every approximate unit for $D$ is also an approximate unit for $A$. This permits removal of the non-degeneracy hypothesis from the definition of a Cartan MASA in the non-unital case. ","PeriodicalId":50369,"journal":{"name":"Indiana University Mathematics Journal","volume":"55 1","pages":"0"},"PeriodicalIF":1.2000,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":"{\"title\":\"Normalizers and approximate units for inclusions of C^*-algebras\",\"authors\":\"David R. Pitts\",\"doi\":\"10.1512/iumj.2023.72.9539\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"For an inclusion of C*-algebras $D\\\\subseteq A$ with $D$ abelian, we show that when $n\\\\in A$ normalizes $D$, $n^*n$ and $nn^*$ commute with $D$. As a corollary, when $D$ is a regular MASA in $A$, every approximate unit for $D$ is also an approximate unit for $A$. This permits removal of the non-degeneracy hypothesis from the definition of a Cartan MASA in the non-unital case. \",\"PeriodicalId\":50369,\"journal\":{\"name\":\"Indiana University Mathematics Journal\",\"volume\":\"55 1\",\"pages\":\"0\"},\"PeriodicalIF\":1.2000,\"publicationDate\":\"2023-01-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"1\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Indiana University Mathematics Journal\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1512/iumj.2023.72.9539\",\"RegionNum\":2,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Indiana University Mathematics Journal","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1512/iumj.2023.72.9539","RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 1
摘要
对于包含C*-代数$D\subseteq A$和$D$阿贝尔,我们证明了当$n\在A$中归一化$D$时,$n^*n$和$nn^*$与$D$交换。作为推论,当$D$是$ a $中的正则MASA时,$D$的每一个近似单位也是$ a $的近似单位。这允许在非单情况下从Cartan MASA的定义中去除非简并假设。
Normalizers and approximate units for inclusions of C^*-algebras
For an inclusion of C*-algebras $D\subseteq A$ with $D$ abelian, we show that when $n\in A$ normalizes $D$, $n^*n$ and $nn^*$ commute with $D$. As a corollary, when $D$ is a regular MASA in $A$, every approximate unit for $D$ is also an approximate unit for $A$. This permits removal of the non-degeneracy hypothesis from the definition of a Cartan MASA in the non-unital case.