In this paper, we establish global boundedness results for the jet determination order of CR maps between (not necessarily bounded) generic submanifolds in complex space. A key feature of our results is that they apply to Nash submanifolds, but do not extend to arbitrary real-analytic submanifolds.
{"title":"Global boundedness of the jet determination order for holomorphic mappings between generic Nash submanifolds in complex space","authors":"Nordine Mir","doi":"10.1112/blms.70250","DOIUrl":"https://doi.org/10.1112/blms.70250","url":null,"abstract":"<p>In this paper, we establish global boundedness results for the jet determination order of CR maps between (not necessarily bounded) generic submanifolds in complex space. A key feature of our results is that they apply to Nash submanifolds, but do not extend to arbitrary real-analytic submanifolds.</p>","PeriodicalId":55298,"journal":{"name":"Bulletin of the London Mathematical Society","volume":"58 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146091289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We classify all contact structures on 3-manifolds that admit a nonfree toric action, up to contactomorphism, and present them through explicit topological descriptions. Our classification is based on Lerman's classification of toric contact 3-manifolds up to equivariant contactomorphism [Lerman, J. Symplectic Geom. 1 (2003), 785–828]. We also prove that every contact 3-manifold with a nonfree toric action arises as the concave boundary of a toric linear plumbing over spheres inspired by Marinković et al. As a corollary of both results, we classify which contact 3-manifolds arise as the concave boundary of a linear plumbing of spheres.
我们对3流形上所有承认非自由环向作用的接触结构进行了分类,直到接触同构,并通过显式拓扑描述给出了它们。我们的分类是基于Lerman的环形接触3流形直到等变接触同构的分类[Lerman, J. simpltic Geom. 1(2003), 785-828]。我们还证明了每一个具有非自由环向作用的接触3流形都是由marinkovovic等人启发的球面上的环向线性管道的凹边界产生的。作为这两个结果的推论,我们分类了哪些接触3流形出现在球面线性管道的凹边界上。
{"title":"On contact 3-manifolds that admit a nonfree toric action","authors":"Aleksandra Marinković, Laura Starkston","doi":"10.1112/blms.70259","DOIUrl":"https://doi.org/10.1112/blms.70259","url":null,"abstract":"<p>We classify all contact structures on 3-manifolds that admit a nonfree toric action, up to contactomorphism, and present them through explicit topological descriptions. Our classification is based on Lerman's classification of toric contact 3-manifolds up to equivariant contactomorphism [Lerman, J. Symplectic Geom. <b>1</b> (2003), 785–828]. We also prove that every contact 3-manifold with a nonfree toric action arises as the concave boundary of a toric linear plumbing over spheres inspired by Marinković et al. As a corollary of both results, we classify which contact 3-manifolds arise as the concave boundary of a linear plumbing of spheres.</p>","PeriodicalId":55298,"journal":{"name":"Bulletin of the London Mathematical Society","volume":"58 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://londmathsoc.onlinelibrary.wiley.com/doi/epdf/10.1112/blms.70259","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146099323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We give two short proofs of the abelian Livšic theorem of Gogolev and Rodriguez Hertz. We show that these proofs may be extended to give new abelian Livšic theorems for positive density sets of null-homologous orbits and for amenable covers.
{"title":"Abelian Livšic theorems for Anosov flows","authors":"Richard Sharp","doi":"10.1112/blms.70258","DOIUrl":"https://doi.org/10.1112/blms.70258","url":null,"abstract":"<p>We give two short proofs of the abelian Livšic theorem of Gogolev and Rodriguez Hertz. We show that these proofs may be extended to give new abelian Livšic theorems for positive density sets of null-homologous orbits and for amenable covers.</p>","PeriodicalId":55298,"journal":{"name":"Bulletin of the London Mathematical Society","volume":"58 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://londmathsoc.onlinelibrary.wiley.com/doi/epdf/10.1112/blms.70258","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146091053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we investigate a special autonomous Schwarzian differential equation
本文研究一类特殊的自治Schwarzian微分方程
{"title":"A note on autonomous Schwarzian differential equations","authors":"Dong-hai Zhao, Jie Zhang, Liang-wen Liao","doi":"10.1112/blms.70256","DOIUrl":"https://doi.org/10.1112/blms.70256","url":null,"abstract":"<p>In this paper, we investigate a special autonomous Schwarzian differential equation\u0000\u0000 </p>","PeriodicalId":55298,"journal":{"name":"Bulletin of the London Mathematical Society","volume":"58 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146091009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We show that the ‘profinite direct sum’ is a good notion of infinite direct sums for profinite modules, having properties similar to those of direct sums of abstract modules. For example, the profinite direct sum of projective modules is projective, and there is a Mackey's formula for profinite modules described using these sums. As an application, we prove that the class of profinite groups of type