On discreteness of commensurators
نویسندگان
چکیده
منابع مشابه
On Discreteness of Commensurators
We begin by showing that commensurators of Zariski dense subgroups of isometry groups of symmetric spaces of non-compact type are discrete provided that the limit set on the Furstenberg boundary is not invariant under the action of a (virtual) simple factor. In particular for rank one or simple Lie groups, Zariski dense subgroups with non-empty domain of discontinuity have discrete commensurato...
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We prove that the abstract commensurator of a nontrivial free group, an infinite surface group, or more generally a group that splits appropriately over a cyclic subgroup is not finitely generated. This applies in particular to all torsion-free word-hyperbolic groups with infinite outer automorphism group and abelianization of rank at least 2. We also construct a finitely generated group which ...
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ژورنال
عنوان ژورنال: Geometry & Topology
سال: 2011
ISSN: 1364-0380,1465-3060
DOI: 10.2140/gt.2011.15.331