{"title":"线上群作用模空间的实现结果","authors":"Joaquín Brum, Nicolás Matte Bon, Cristóbal Rivas, Michele Triestino","doi":"10.1112/topo.12357","DOIUrl":null,"url":null,"abstract":"<p>Given a finitely generated group <span></span><math>\n <semantics>\n <mi>G</mi>\n <annotation>$G$</annotation>\n </semantics></math>, the possible actions of <span></span><math>\n <semantics>\n <mi>G</mi>\n <annotation>$G$</annotation>\n </semantics></math> on the real line (without global fixed points), considered up to semi-conjugacy, can be encoded by the space of orbits of a flow on a compact space <span></span><math>\n <semantics>\n <mrow>\n <mo>(</mo>\n <mi>Y</mi>\n <mo>,</mo>\n <mi>Φ</mi>\n <mo>)</mo>\n </mrow>\n <annotation>$(Y, \\Phi)$</annotation>\n </semantics></math> naturally associated with <span></span><math>\n <semantics>\n <mi>G</mi>\n <annotation>$G$</annotation>\n </semantics></math> and uniquely defined up to flow equivalence, that we call the <i>Deroin space</i> of <span></span><math>\n <semantics>\n <mi>G</mi>\n <annotation>$G$</annotation>\n </semantics></math>. We show a realisation result: every expansive flow <span></span><math>\n <semantics>\n <mrow>\n <mo>(</mo>\n <mi>Y</mi>\n <mo>,</mo>\n <mi>Φ</mi>\n <mo>)</mo>\n </mrow>\n <annotation>$(Y, \\Phi)$</annotation>\n </semantics></math> on a compact metrisable space of topological dimension 1, satisfying some mild additional assumptions, arises as the Deroin space of a finitely generated group. This is proven by identifying the Deroin space of an explicit family of groups acting on suspension flows of subshifts, which is a variant of a construction introduced by the second and fourth authors. This result provides a source of examples of finitely generated groups satisfying various new phenomena for actions on the line, related to their rigidity/flexibility properties and to the structure of (path-)connected components of the space of actions.</p>","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":"17 4","pages":""},"PeriodicalIF":0.8000,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"A realisation result for moduli spaces of group actions on the line\",\"authors\":\"Joaquín Brum, Nicolás Matte Bon, Cristóbal Rivas, Michele Triestino\",\"doi\":\"10.1112/topo.12357\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Given a finitely generated group <span></span><math>\\n <semantics>\\n <mi>G</mi>\\n <annotation>$G$</annotation>\\n </semantics></math>, the possible actions of <span></span><math>\\n <semantics>\\n <mi>G</mi>\\n <annotation>$G$</annotation>\\n </semantics></math> on the real line (without global fixed points), considered up to semi-conjugacy, can be encoded by the space of orbits of a flow on a compact space <span></span><math>\\n <semantics>\\n <mrow>\\n <mo>(</mo>\\n <mi>Y</mi>\\n <mo>,</mo>\\n <mi>Φ</mi>\\n <mo>)</mo>\\n </mrow>\\n <annotation>$(Y, \\\\Phi)$</annotation>\\n </semantics></math> naturally associated with <span></span><math>\\n <semantics>\\n <mi>G</mi>\\n <annotation>$G$</annotation>\\n </semantics></math> and uniquely defined up to flow equivalence, that we call the <i>Deroin space</i> of <span></span><math>\\n <semantics>\\n <mi>G</mi>\\n <annotation>$G$</annotation>\\n </semantics></math>. We show a realisation result: every expansive flow <span></span><math>\\n <semantics>\\n <mrow>\\n <mo>(</mo>\\n <mi>Y</mi>\\n <mo>,</mo>\\n <mi>Φ</mi>\\n <mo>)</mo>\\n </mrow>\\n <annotation>$(Y, \\\\Phi)$</annotation>\\n </semantics></math> on a compact metrisable space of topological dimension 1, satisfying some mild additional assumptions, arises as the Deroin space of a finitely generated group. This is proven by identifying the Deroin space of an explicit family of groups acting on suspension flows of subshifts, which is a variant of a construction introduced by the second and fourth authors. This result provides a source of examples of finitely generated groups satisfying various new phenomena for actions on the line, related to their rigidity/flexibility properties and to the structure of (path-)connected components of the space of actions.</p>\",\"PeriodicalId\":56114,\"journal\":{\"name\":\"Journal of Topology\",\"volume\":\"17 4\",\"pages\":\"\"},\"PeriodicalIF\":0.8000,\"publicationDate\":\"2024-10-05\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Topology\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1112/topo.12357\",\"RegionNum\":2,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Topology","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1112/topo.12357","RegionNum":2,"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
摘要
给定一个有限生成的群 G $G$,G $G$在实线(无全局定点)上的可能作用,考虑到半共轭,可以用一个紧凑空间 ( Y , Φ ) $(Y, \Phi)$ 上的流的轨道空间来编码,这个紧凑空间与 G $G$自然相关,并且唯一定义到流等价,我们称之为 G $G$的 Deroin 空间。我们展示了一个实现结果:在拓扑维度为 1 的紧凑可元空间上的每一个扩张流 ( Y , Φ ) $(Y, \Phi)$ 在满足一些温和的附加假设后,都会作为有限生成群的 Deroin 空间出现。这是通过识别作用于子转移悬浮流的显式群族的 Deroin 空间来证明的,这是第二和第四作者提出的一种构造的变体。这一结果提供了有限生成的群满足直线上作用的各种新现象的例子,这些新现象与它们的刚性/柔性特性和作用空间的(路径)连接成分的结构有关。
A realisation result for moduli spaces of group actions on the line
Given a finitely generated group , the possible actions of on the real line (without global fixed points), considered up to semi-conjugacy, can be encoded by the space of orbits of a flow on a compact space naturally associated with and uniquely defined up to flow equivalence, that we call the Deroin space of . We show a realisation result: every expansive flow on a compact metrisable space of topological dimension 1, satisfying some mild additional assumptions, arises as the Deroin space of a finitely generated group. This is proven by identifying the Deroin space of an explicit family of groups acting on suspension flows of subshifts, which is a variant of a construction introduced by the second and fourth authors. This result provides a source of examples of finitely generated groups satisfying various new phenomena for actions on the line, related to their rigidity/flexibility properties and to the structure of (path-)connected components of the space of actions.
期刊介绍:
The Journal of Topology publishes papers of high quality and significance in topology, geometry and adjacent areas of mathematics. Interesting, important and often unexpected links connect topology and geometry with many other parts of mathematics, and the editors welcome submissions on exciting new advances concerning such links, as well as those in the core subject areas of the journal.
The Journal of Topology was founded in 2008. It is published quarterly with articles published individually online prior to appearing in a printed issue.