Discrete subgroups

  • Roelof W. Bruggeman
Part of the Modern Birkhäuser Classics book series (MBC)


This chapter describes the class of discrete subgroups of the universal covering group that we shall consider: the cofinite discrete subgroups. The covering \(\tilde \Gamma \) of the modular group and all its subgroups of finite index belong to this class. This includes the groups \({\tilde \Gamma _\theta }\) and \({\tilde \Gamma _{com}}\) considered in the Chapters 14 and 15. There are many more cofinite discrete groups; most of them have nothing to do with the modular group.


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Copyright information

© Springer Basel AG 1994

Authors and Affiliations

  • Roelof W. Bruggeman
    • 1
  1. 1.Mathematisch InstituutUniversiteit UtrechtUtrechtThe Netherland

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