Inventiones mathematicae

, Volume 149, Issue 3, pp 579–617 | Cite as

The residual finiteness of negatively curved polygons of finite groups

  • Daniel T. Wise


A subgroup MG is almost malnormal provided that for each gGM, the intersection M g M is finite. It is proven that the free product of two virtually free groups amalgamating a finitely generated almost malnormal subgroup, is residually finite. A consequence of a generalization of this result is that an acute-angled n-gon of finite groups is residually finite if n≥4. Another consequence is that if G acts properly discontinuously and cocompactly on a 2-dimensional hyperbolic building whose chambers have acute angles and at least 4 sides, then G is residually finite.

Mathematical Subject Classification (2000): 20E05, 20E06, 20E26, 20F32 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • Daniel T. Wise
    • 1
  1. 1.Department of Mathematics, UC Berkeley, Berkeley, CA 94720, USAUS

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