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Almost quasi-isometries and more non-C*-exact groups

Published online by Cambridge University Press:  14 July 2016

MARTIN FINN-SELL
MARTIN FINN-SELL*
Affiliation:
Fakultät für Mathematik, Oskar-Morgenstern-Platz 1, 1090 Wien, Österreich. e-mails: martin.finn-sell@univie.ac.at
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Abstract

We study permanence results for almost quasi-isometries, the maps arising from the Gromov construction of finitely generated random groups that contain expanders (and hence that are not C*-exact). We show that the image of a sequence of finite graphs of large girth and controlled vertex degrees under an almost quasi-isometry does not have Guoliang Yu's property A. We use this result to broaden the application of Gromov's techniques to sequences of graphs which are not necessarily expanders. Thus, we obtain more examples of finitely generated non-C*-exact groups.

Type
Research Article
Information
Mathematical Proceedings of the Cambridge Philosophical Society , Volume 162 , Issue 3 , May 2017 , pp. 393 - 403
Copyright
Copyright © Cambridge Philosophical Society 2016 

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