Abstract
In this paper we study band truncation approximations for operators in uniform Roe algebras of countable discrete groups. Under conditions on certain growth rates for discrete groups, we find large classes of dense subspaces of uniform Roe algebras whose elements can be approximated by their band truncations in the operator norm. We apply these results to construct a nested family of spectral invariant Banach algebras on discrete groups. For a group with polynomial growth, the intersection of these Banach algebras is a spectral invariant dense subalgebra of the uniform Roe algebra. For a group with subexponential growth, we show that the Wiener algebra of the group is a spectral invariant dense subalgebra of the uniform Roe algebra.
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Acknowledgments
The authors wish to thank the referees for their huge amount of corrections, explanations, and valuable comments on the original version of this paper. The authors are also very grateful to Taxas A&M University for its support and hospitality during their visits. The second author wishes to thank the Erwin Schrödinger International Institute for Mathematical Physics, Universität Wien, for its support and hospitality during his visit in April, 2014, in the Workshop on “Geometry of Computation in Groups”. The third author is also indebted to the China Scholarship Council for its support. The authors are supported in part by NSFC (No. 11231002, 11420101001, 10901033, 10971023).
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Communicated by Hans G. Feichtinger.
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Chen, X., Wang, Q. & Wang, X. Truncation Approximations and Spectral Invariant Subalgebras in Uniform Roe Algebras of Discrete Groups. J Fourier Anal Appl 21, 555–574 (2015). https://doi.org/10.1007/s00041-014-9380-z
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DOI: https://doi.org/10.1007/s00041-014-9380-z
Keywords
- Discrete group
- Uniform Roe algebra
- Truncation approximation
- Spectral invariant subalgebra
- Wiener algebra