English

A computation with the Connes-Thom isomorphism

Operator Algebras 2012-03-05 v1 K-Theory and Homology

Abstract

Let AMn(R)A \in M_{n}(\mathbb{R}) be an invertible matrix. Consider the semi-direct product RnZ\mathbb{R}^{n} \rtimes \mathbb{Z} where Z\mathbb{Z} acts on Rn\mathbb{R}^{n} by matrix multiplication. Consider a strongly continuous action (α,τ)(\alpha,\tau) of RnZ\mathbb{R}^{n} \rtimes \mathbb{Z} on a CC^{*}-algebra BB where α\alpha is a strongly continuous action of Rn\mathbb{R}^{n} and τ\tau is an automorphism. The map τ\tau induces a map τ~\widetilde{\tau} on BαRnB \rtimes_{\alpha} \mathbb{R}^{n}. We show that, at the KK-theory level, τ\tau commutes with the Connes-Thom map if det(A)>0\det(A)>0 and anticommutes if det(A)<0\det(A)<0. As an application, we recompute the KK-groups of the Cuntz-Li algebra associated to an integer dilation matrix.

Keywords

Cite

@article{arxiv.1203.0383,
  title  = {A computation with the Connes-Thom isomorphism},
  author = {S. Sundar},
  journal= {arXiv preprint arXiv:1203.0383},
  year   = {2012}
}
R2 v1 2026-06-21T20:27:58.826Z