Abstract
We address two questions of Simon Thomas. First, we show that for any n ≥ 3 one can find a four-generated free subgroup of SLn(ℤ) which is profinitely dense. More generally, we show that an arithmetic group Γ that admits the congruence subgroup property has a profinitely-dense free subgroup with an explicit bound on its rank. Next, we show that the set of profinitely-dense, locally-free subgroups of such an arithmetic group Γ is uncountable.
Original language | English |
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Pages (from-to) | 525-539 |
Number of pages | 15 |
Journal | Journal of Group Theory |
Volume | 17 |
Issue number | 4 |
DOIs | |
State | Published - 1 Jul 2014 |
Bibliographical note
Funding Information:We acknowledge the support of the ERC grant 226135, the ERC grant 203418, the ISEF foundation, the Ilan and Asaf Ramon memorial foundation, the “Hoffman Leadership and Responsibility” fellowship program, the ISF grant 1003/11, the BSF grant 2010295, the SFB grant 701 “Spektrale Strukturen und TopologischeMethoden in der Mathematik”, the Emmy Noether Research Institute for Mathematics Bar-Ilan University, the Israel Science Foundation under ISF grant 657/09 and the Max Planck Institute for Mathematics, Bonn.
Funding
We acknowledge the support of the ERC grant 226135, the ERC grant 203418, the ISEF foundation, the Ilan and Asaf Ramon memorial foundation, the “Hoffman Leadership and Responsibility” fellowship program, the ISF grant 1003/11, the BSF grant 2010295, the SFB grant 701 “Spektrale Strukturen und TopologischeMethoden in der Mathematik”, the Emmy Noether Research Institute for Mathematics Bar-Ilan University, the Israel Science Foundation under ISF grant 657/09 and the Max Planck Institute for Mathematics, Bonn.
Funders | Funder number |
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Emmy Noether Research Institute for Mathematics Bar-Ilan University | |
Hoffman Leadership and Responsibility | |
Ilan and Asaf Ramon memorial foundation | |
Max Planck Institute for Mathematics | |
Bloom's Syndrome Foundation | 2010295 |
ISEF Foundation | |
Seventh Framework Programme | 226135, 203418 |
Iowa Science Foundation | 1003/11 |
European Commission | |
Israel Science Foundation | 657/09 |