{"title":"Tracial weights on topological graph algebras","authors":"JOHANNES CHRISTENSEN","doi":"10.1017/etds.2024.20","DOIUrl":null,"url":null,"abstract":"<p>We describe two kinds of regular invariant measures on the boundary path space <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240304092108222-0628:S0143385724000208:S0143385724000208_inline1.png\"><span data-mathjax-type=\"texmath\"><span>$\\partial E$</span></span></img></span></span> of a second countable topological graph <span>E</span>, which allows us to describe all extremal tracial weights on <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240304092108222-0628:S0143385724000208:S0143385724000208_inline2.png\"><span data-mathjax-type=\"texmath\"><span>$C^{*}(E)$</span></span></img></span></span> which are not gauge-invariant. Using this description, we prove that all tracial weights on the C<span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240304092108222-0628:S0143385724000208:S0143385724000208_inline3.png\"><span data-mathjax-type=\"texmath\"><span>$^{*}$</span></span></img></span></span>-algebra <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240304092108222-0628:S0143385724000208:S0143385724000208_inline4.png\"><span data-mathjax-type=\"texmath\"><span>$C^{*}(E)$</span></span></img></span></span> of a second countable topological graph <span>E</span> are gauge-invariant when <span>E</span> is free. This in particular implies that all tracial weights on <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240304092108222-0628:S0143385724000208:S0143385724000208_inline5.png\"><span data-mathjax-type=\"texmath\"><span>$C^{*}(E)$</span></span></img></span></span> are gauge-invariant when <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240304092108222-0628:S0143385724000208:S0143385724000208_inline6.png\"><span data-mathjax-type=\"texmath\"><span>$C^{*}(E)$</span></span></img></span></span> is simple and separable.</p>","PeriodicalId":50504,"journal":{"name":"Ergodic Theory and Dynamical Systems","volume":"67 1","pages":""},"PeriodicalIF":0.8000,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ergodic Theory and Dynamical Systems","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1017/etds.2024.20","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
We describe two kinds of regular invariant measures on the boundary path space $\partial E$ of a second countable topological graph E, which allows us to describe all extremal tracial weights on $C^{*}(E)$ which are not gauge-invariant. Using this description, we prove that all tracial weights on the C$^{*}$-algebra $C^{*}(E)$ of a second countable topological graph E are gauge-invariant when E is free. This in particular implies that all tracial weights on $C^{*}(E)$ are gauge-invariant when $C^{*}(E)$ is simple and separable.
期刊介绍:
Ergodic Theory and Dynamical Systems focuses on a rich variety of research areas which, although diverse, employ as common themes global dynamical methods. The journal provides a focus for this important and flourishing area of mathematics and brings together many major contributions in the field. The journal acts as a forum for central problems of dynamical systems and of interactions of dynamical systems with areas such as differential geometry, number theory, operator algebras, celestial and statistical mechanics, and biology.