### Abstract

For a Haken 3-manifold M with incompressible boundary, we prove that the mapping class group H(M) acts properly discontinuously on a contractible simplicial complex, with compact quotient. This implies that every torsionfree subgroup of finite index in H(M) is geometrically finite. Also, a simplified proof of the fact that torsionfree subgroups of finite index in H(M) exist is given. All results are given for mapping class groups that preserve a boundary pattern in the sense of K. Johannson. As an application, we show that if F is a nonempty compact 2-manifold in ∂M such that ∂M - F is incompressible, then the classifying space BDiff(M rel F) of the diffeomorphism group of M relative to F has the homotopy type of a finite aspherical complex.

Original language | English |
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Pages (from-to) | 275-301 |

Number of pages | 27 |

Journal | Pacific Journal of Mathematics |

Volume | 188 |

Issue number | 2 |

DOIs | |

Publication status | Published - 1999 Apr |

### ASJC Scopus subject areas

- Mathematics(all)

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## Cite this

*Pacific Journal of Mathematics*,

*188*(2), 275-301. https://doi.org/10.2140/pjm.1999.188.275