A modification of the Ford geometric approach to the problem of approximation of complex numbers by elements of an imaginary quadratic number field is developed. An upper bound for the Hurwitz constant for the field is obtained in terms of the geometry of the isometric fundamental domain for the cor
Sofic groups and diophantine approximation
โ Scribed by Andreas Thom
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 157 KB
- Volume
- 61
- Category
- Article
- ISSN
- 0010-3640
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โฆ Synopsis
Abstract
We prove the algebraic eigenvalue conjecture of J. Dodziuk, P. Linnell, V. Mathai, T. Schick, and S. Yates (see [2]) for sofic groups. Moreover, we give restrictions on the spectral measure of elements in the integral group ring. Finally, we define integer operators and prove a quantization of the operator norm below 2. To the knowledge of the author, there is no group known that is not sofic. ยฉ 2007 Wiley Periodicals, Inc.
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