Proper Kasparov Cycles and the Baum-Connes Conjecture
Abstract
We introduce the notion of proper Kasparov cycles for Kasparov's G-equivariant KK-theory for a general locally compact, second countable topological group G. We show that for any proper Kasparov cycle, its induced map on K-theory factors through the left-hand side of the Baum-Connes conjecture. This allows us to upgrade the direct splitting method, a recent new approach to the Baum-Connes conjecture which, in contrast to the standard gamma element method (the Dirac dual-Dirac method), avoids the need of constructing proper algebras and the Dirac and the dual-Dirac elements. We introduce the notion of Kasparov cycles with Property (gamma) removing the G-compact assumption on the universal space EG in the previous paper "Direct Splitting Method for the Baum-Connes Conjecture". We show that the existence of a cycle with Property (gamma) implies the split-injectivity of the Baum-Connes assembly map for all coefficients. We also obtain results concerning the surjectivity of the assembly map.
Keywords
Cite
@article{arxiv.1909.07844,
title = {Proper Kasparov Cycles and the Baum-Connes Conjecture},
author = {Shintaro Nishikawa},
journal= {arXiv preprint arXiv:1909.07844},
year = {2020}
}
Comments
This paper has been withdrawn: there are unfixable mistakes in the proof of Proposition 1.6 (at the last equality, page 9) and in the proof of Lemma 1.34 (at the first line, page 30). Lemma 1.34 was crucial for the proof of main theorems, namely Theorem A and B