English

Permanence properties of property A and coarse embeddability for locally compact groups

Operator Algebras 2014-03-28 v1 Group Theory K-Theory and Homology Metric Geometry

Abstract

If HH is a lattice in a locally compact second countable group GG, then we show that GG has property A (respectively is coarsely embeddable into Hilbert space) if and only if HH has property A (respectively is coarsely embeddable into Hilbert space). Moreover, we show three interesting generalizations of this result. If HH is a closed subgroup of GG that is co-amenable in GG, and if HH has property A (respectively, is coarsely embeddable into Hilbert space), then we show that GG has property A (respectively, is coarsely embeddable into Hilbert space). We also show that an extension of property A groups still has property A. On the coarse embeddability side, we show that if {e}HGQ{e}\{e\}\rightarrow H\rightarrow G\rightarrow Q\rightarrow\{e\} is a short exact sequence, and if either HH is coarsely embeddable into Hilbert space and QQ has property A, or HH is compact and QQ is coarsely embeddable into Hilbert space, then GG is coarsely embeddable into Hilbert space. We extend the theory of measure equivalence to locally compact non-unimodular groups. In a natural way, we can also define measure equivalence subgroups. We show that property A and uniform embeddability into Hilbert space pass to measure equivalence subgroups. Using the same techniques, we show that also the Haagerup property, weak amenability and the weak Haagerup property pass to measure equivalence subgroups.

Keywords

Cite

@article{arxiv.1403.7111,
  title  = {Permanence properties of property A and coarse embeddability for locally compact groups},
  author = {Steven Deprez and Kang Li},
  journal= {arXiv preprint arXiv:1403.7111},
  year   = {2014}
}