<p>We consider 3-manifolds admitting the action of an involution such that its space of orbits is homeomorphic to <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13163_2025_523_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="25" /> </InlineMediaObject> <EquationSource Format="TEX">\(S^3.\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>S</mi> <mn>3</mn> </msup> <mo>.</mo> </mrow> </math></EquationSource> </InlineEquation> Such involutions are called <i>hyperelliptic</i> as the manifolds admitting such an action. We prove that the sectional 2-rank of a finite group acting on a 3-manifold and containing a hyperelliptic involution whose fixed-point set has two components has sectional 2-rank at most four; this upper bound is sharp. The cases where the hyperelliptic involution has a fixed-point set with a number of components different from 2 have been already considered in the literature. Our result completes the analysis and we obtain general results where the number of the components of the fixed-point set is not fixed. In particular, we obtain that a finite group acting on a 3-manifold and containing a hyperelliptic involution has 2-rank at most four, and four is the best possible upper bound. Finally, we restrict to the basic case of simple groups acting on hyperelliptic 3-manifolds: we use our result about the sectional 2-rank to prove that a simple group containing a hyperelliptic involution is isomorphic to <i>PSL</i>(2,&#xa0;<i>q</i>) for some odd prime power <i>q</i>, or to one of four other small simple groups.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

The 2-rank of finite groups acting on hyperelliptic 3-manifolds

  • Max Leopold Frisch Sbarra,
  • Mattia Mecchia

摘要

We consider 3-manifolds admitting the action of an involution such that its space of orbits is homeomorphic to \(S^3.\) S 3 . Such involutions are called hyperelliptic as the manifolds admitting such an action. We prove that the sectional 2-rank of a finite group acting on a 3-manifold and containing a hyperelliptic involution whose fixed-point set has two components has sectional 2-rank at most four; this upper bound is sharp. The cases where the hyperelliptic involution has a fixed-point set with a number of components different from 2 have been already considered in the literature. Our result completes the analysis and we obtain general results where the number of the components of the fixed-point set is not fixed. In particular, we obtain that a finite group acting on a 3-manifold and containing a hyperelliptic involution has 2-rank at most four, and four is the best possible upper bound. Finally, we restrict to the basic case of simple groups acting on hyperelliptic 3-manifolds: we use our result about the sectional 2-rank to prove that a simple group containing a hyperelliptic involution is isomorphic to PSL(2, q) for some odd prime power q, or to one of four other small simple groups.