<p>This paper studies the relationship between an analytic compactification of the moduli space of flat <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="normal">SL</mi> <mn>2</mn> </msub> <mo stretchy="false">(</mo> <mi mathvariant="double-struck">C</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$\mathrm{SL}_{2}(\mathbb{C})$</EquationSource> </InlineEquation> connections on a closed, oriented 3-manifold <InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math> <mi>M</mi> </math></EquationSource> <EquationSource Format="TEX">$M$</EquationSource> </InlineEquation> defined by Taubes, and the Morgan–Shalen compactification of the <InlineEquation ID="IEq4"> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="normal">SL</mi> <mn>2</mn> </msub> <mo stretchy="false">(</mo> <mi mathvariant="double-struck">C</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$\mathrm{SL}_{2}(\mathbb{C})$</EquationSource> </InlineEquation> character variety of the fundamental group of <InlineEquation ID="IEq5"> <EquationSource Format="MATHML"><math> <mi>M</mi> </math></EquationSource> <EquationSource Format="TEX">$M$</EquationSource> </InlineEquation>. We exhibit an explicit correspondence between <InlineEquation ID="IEq6"> <EquationSource Format="MATHML"><math> <mi mathvariant="double-struck">Z</mi> <mo stretchy="false">/</mo> <mn>2</mn> </math></EquationSource> <EquationSource Format="TEX">$\mathbb{Z}/2$</EquationSource> </InlineEquation> harmonic 1-forms, measured foliations, and equivariant harmonic maps to ℝ-trees, as initially proposed by Taubes. As an application, we prove that <InlineEquation ID="IEq7"> <EquationSource Format="MATHML"><math> <mi mathvariant="double-struck">Z</mi> <mo stretchy="false">/</mo> <mn>2</mn> </math></EquationSource> <EquationSource Format="TEX">$\mathbb{Z}/2$</EquationSource> </InlineEquation> harmonic 1-forms exist on all reducible or Haken manifolds with respect to all Riemannian metrics. We also prove the existence of manifolds which support singular <InlineEquation ID="IEq8"> <EquationSource Format="MATHML"><math> <mi mathvariant="double-struck">Z</mi> <mo stretchy="false">/</mo> <mn>2</mn> </math></EquationSource> <EquationSource Format="TEX">$\mathbb{Z}/2$</EquationSource> </InlineEquation> harmonic 1-forms but which have compact <InlineEquation ID="IEq9"> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="normal">SL</mi> <mn>2</mn> </msub> <mo stretchy="false">(</mo> <mi mathvariant="double-struck">C</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$\mathrm{SL}_{2}(\mathbb{C})$</EquationSource> </InlineEquation> character varieties, and this resolves a folklore conjecture.</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

\(\mathbb{Z}/2\) harmonic 1-forms, ℝ-trees, and the Morgan-Shalen compactification

  • Siqi He,
  • Richard Wentworth,
  • Boyu Zhang

摘要

This paper studies the relationship between an analytic compactification of the moduli space of flat SL 2 ( C ) $\mathrm{SL}_{2}(\mathbb{C})$ connections on a closed, oriented 3-manifold M $M$ defined by Taubes, and the Morgan–Shalen compactification of the SL 2 ( C ) $\mathrm{SL}_{2}(\mathbb{C})$ character variety of the fundamental group of M $M$ . We exhibit an explicit correspondence between Z / 2 $\mathbb{Z}/2$ harmonic 1-forms, measured foliations, and equivariant harmonic maps to ℝ-trees, as initially proposed by Taubes. As an application, we prove that Z / 2 $\mathbb{Z}/2$ harmonic 1-forms exist on all reducible or Haken manifolds with respect to all Riemannian metrics. We also prove the existence of manifolds which support singular Z / 2 $\mathbb{Z}/2$ harmonic 1-forms but which have compact SL 2 ( C ) $\mathrm{SL}_{2}(\mathbb{C})$ character varieties, and this resolves a folklore conjecture.