English

Commutators Close to the Identity in Unital C*-Algebras

Operator Algebras 2021-04-06 v1

Abstract

Let H\mathcal{H} be an infinite dimensional Hilbert space and B(H)\mathcal{B}(\mathcal{H}) be the C*-algebra of all bounded linear operators on H\mathcal{H}, equipped with the operator-norm. By improving the Brown-Pearcy construction, Terence Tao in 2018, extended the result of Popa [1981] which reads as : For each 0<ε1/20<\varepsilon\leq 1/2, there exist D,XB(H)D,X \in \mathcal{B}(\mathcal{H}) with [D,X]1B(H)ε\|[D,X]-1_{\mathcal{B}(\mathcal{H})}\|\leq \varepsilon such that DX=O(log51ε)\|D\|\|X\|=O\left(\log^5\frac{1}{\varepsilon}\right), where [D,X]:=DXXD[D,X]:= DX-XD. In this paper, we show that Tao's result still holds for certain class of unital C*-algebras which include B(H)\mathcal{B}(\mathcal{H}) as well as the Cuntz algebra O2\mathcal{O}_2.

Keywords

Cite

@article{arxiv.2104.02035,
  title  = {Commutators Close to the Identity in Unital C*-Algebras},
  author = {K. Mahesh Krishna and P. Sam Johnson},
  journal= {arXiv preprint arXiv:2104.02035},
  year   = {2021}
}

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10 pages