English

Quasi-representations of groups and two-homology

Operator Algebras 2022-04-20 v1 K-Theory and Homology

Abstract

The Exel-Loring formula asserts that two topological invariants associated to a pair of almost commuting unitary matrices coincide. Such a pair can be viewed as a quasi-representation of Z2\mathbb{Z}^2. We give a generalization of this formula for countable discrete groups. We also show the nontriviality of the corresponding invariants for quasidiagonal groups which are coarsely embeddable in a Hilbert space and have nonvanishing second Betti number.

Keywords

Cite

@article{arxiv.2111.05755,
  title  = {Quasi-representations of groups and two-homology},
  author = {Marius Dadarlat},
  journal= {arXiv preprint arXiv:2111.05755},
  year   = {2022}
}