{"title":"Legendrian non-isotopic unit conormal bundles in high dimensions","authors":"Yukihiro Okamoto","doi":"10.1112/topo.70039","DOIUrl":"https://doi.org/10.1112/topo.70039","url":null,"abstract":"<p>For any compact connected submanifold <span></span><math>\u0000 <semantics>\u0000 <mi>K</mi>\u0000 <annotation>$K$</annotation>\u0000 </semantics></math> of <span></span><math>\u0000 <semantics>\u0000 <msup>\u0000 <mi>R</mi>\u0000 <mi>n</mi>\u0000 </msup>\u0000 <annotation>$mathbb {R}^n$</annotation>\u0000 </semantics></math>, let <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>Λ</mi>\u0000 <mi>K</mi>\u0000 </msub>\u0000 <annotation>$Lambda _K$</annotation>\u0000 </semantics></math> denote its unit conormal bundle, which is a Legendrian submanifold of the unit cotangent bundle of <span></span><math>\u0000 <semantics>\u0000 <msup>\u0000 <mi>R</mi>\u0000 <mi>n</mi>\u0000 </msup>\u0000 <annotation>$mathbb {R}^n$</annotation>\u0000 </semantics></math>. In this paper, we give examples of pairs <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <msub>\u0000 <mi>K</mi>\u0000 <mn>0</mn>\u0000 </msub>\u0000 <mo>,</mo>\u0000 <msub>\u0000 <mi>K</mi>\u0000 <mn>1</mn>\u0000 </msub>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$(K_0,K_1)$</annotation>\u0000 </semantics></math> of compact connected submanifolds of <span></span><math>\u0000 <semantics>\u0000 <msup>\u0000 <mi>R</mi>\u0000 <mi>n</mi>\u0000 </msup>\u0000 <annotation>$mathbb {R}^n$</annotation>\u0000 </semantics></math> such that <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>Λ</mi>\u0000 <msub>\u0000 <mi>K</mi>\u0000 <mn>0</mn>\u0000 </msub>\u0000 </msub>\u0000 <annotation>$Lambda _{K_0}$</annotation>\u0000 </semantics></math> is not Legendrian isotopic to <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>Λ</mi>\u0000 <msub>\u0000 <mi>K</mi>\u0000 <mn>1</mn>\u0000 </msub>\u0000 </msub>\u0000 <annotation>$Lambda _{K_1}$</annotation>\u0000 </semantics></math>, although they cannot be distinguished by classical invariants. Here, <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>K</mi>\u0000 <mn>1</mn>\u0000 </msub>\u0000 <annotation>$K_1$</annotation>\u0000 </semantics></math> is","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":"18 3","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://londmathsoc.onlinelibrary.wiley.com/doi/epdf/10.1112/topo.70039","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"G\u0000 $G$\u0000 -typical Witt vectors with coefficients and the norm","authors":"Thomas Read","doi":"10.1112/topo.70038","DOIUrl":"https://doi.org/10.1112/topo.70038","url":null,"abstract":"<p>For a profinite group <span></span><math>\u0000 <semantics>\u0000 <mi>G</mi>\u0000 <annotation>$G$</annotation>\u0000 </semantics></math> we describe an abelian group <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>W</mi>\u0000 <mi>G</mi>\u0000 </msub>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>R</mi>\u0000 <mo>;</mo>\u0000 <mi>M</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$W_G(R; M)$</annotation>\u0000 </semantics></math> of <span></span><math>\u0000 <semantics>\u0000 <mi>G</mi>\u0000 <annotation>$G$</annotation>\u0000 </semantics></math>-typical Witt vectors with coefficients in an <span></span><math>\u0000 <semantics>\u0000 <mi>R</mi>\u0000 <annotation>$R$</annotation>\u0000 </semantics></math>-module <span></span><math>\u0000 <semantics>\u0000 <mi>M</mi>\u0000 <annotation>$M$</annotation>\u0000 </semantics></math> (where <span></span><math>\u0000 <semantics>\u0000 <mi>R</mi>\u0000 <annotation>$R$</annotation>\u0000 </semantics></math> is a commutative ring). This simultaneously generalises the ring <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>W</mi>\u0000 <mi>G</mi>\u0000 </msub>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>R</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$W_G(R)$</annotation>\u0000 </semantics></math> of Dress and Siebeneicher and the Witt vectors with coefficients <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>W</mi>\u0000 <mo>(</mo>\u0000 <mi>R</mi>\u0000 <mo>;</mo>\u0000 <mi>M</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$W(R; M)$</annotation>\u0000 </semantics></math> of Dotto, Krause, Nikolaus and Patchkoria, both of which extend the usual Witt vectors of a ring. We use this new variant of Witt vectors to give a purely algebraic description of the zeroth equivariant stable homotopy groups of the Hill–Hopkins–Ravenel norm <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mi>N</mi>\u0000 <mrow>\u0000 <mo>{</mo>\u0000 <mi>e</mi>\u0000 <mo>}</mo>\u0000 ","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":"18 3","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://londmathsoc.onlinelibrary.wiley.com/doi/epdf/10.1112/topo.70038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}