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Commensurations and
subgroups of finite index of Thompson's group $F$
José Burillo, Sean Cleary and Claas E Röver |
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Geometry & Topology 12 (2008) 1701–1709
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Abstract |
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We determine the abstract commensurator of Thompson’s group and describe it in terms of piecewise linear homeomorphisms of the real line. We show is not finitely generated and determine which subgroups of finite index in are isomorphic to . We also show that the natural map from the commensurator group to the quasi-isometry group of is injective. |
Keywords
Thompson group, commensurator
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Mathematical Subject Classification 2000
Primary: 20E34, 20F65
Secondary: 26A30, 20F28
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References |
Publication
Received: 9 November 2007
Revised: 9 May 2008
Accepted: 26 March 2008
Published: 19 June 2008
Proposed: Walter Neumann
Seconded: Benson Farb, Martin Bridson
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Authors |
| José Burillo | |
| Departament de Matemàtica Aplicada
IV Universitat Politècnica de Catalunya Escola Politècnica Superior de Castelldefels Avda. Del Canal Olímpic 15 08860 Castelldefels (Barcelona) Spain |
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| http://www-ma4.upc.edu/~burillo/ | |
| Sean Cleary | |
| Department of Mathematics
R8133 The City College of New York Convent Ave & 138th New York, NY 10031 USA |
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| http://www.sci.ccny.cuny.edu/~cleary/ | |
| Claas E Röver | |
| Department of Mathematics University of Ireland, Galway University Road Galway Ireland |
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| http://www.maths.nuigalway.ie/~chew/ | |
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