Geometriae Dedicata

, Volume 118, Issue 1, pp 1–21

Counting Overlattices in Automorphism Groups of Trees

Article

Abstract

We give an upper bound for the number uΓ(n) of “overlattices” in the automorphism group of a tree, containing a fixed lattice Γ with index n. For an example of Γ in the automorphism group of a 2p-regular tree whose quotient is a loop, we obtain a lower bound of the asymptotic behavior as well.

Keywords

groups acting on trees graph of groups 

Mathematics Subject Classification (2000)

20F65 20E08 

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Copyright information

© Springer 2006

Authors and Affiliations

  1. 1.Yale UniversityNew HavenU.S.A
  2. 2.ENS Paris, UMR 8553Paris Cedex 05France

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