Transactions of the American Mathematical Society

ISSN 1088-6850(online) ISSN 0002-9947(print)



Commutator estimates in $ W^*$-factors

Authors: A. F. Ber and F. A. Sukochev
Journal: Trans. Amer. Math. Soc. 364 (2012), 5571-5587
MSC (2010): Primary 46L57, 46L51, 46L52
Published electronically: May 21, 2012
MathSciNet review: 2931339
Full-text PDF

Abstract | References | Similar Articles | Additional Information

Abstract: Let $ \mathcal {M}$ be a $ W^*$-factor and let $ S\left ( \mathcal {M} \right ) $ be the space of all measurable operators affiliated with $ \mathcal {M}$. It is shown that for any self-adjoint element $ a\in S(\mathcal {M})$ there exists a scalar $ \lambda _0\in \mathbb{R}$, such that for all $ \varepsilon > 0$, there exists a unitary element $ u_\varepsilon $ from $ \mathcal {M}$, satisfying $ \vert[a,u_\varepsilon ]\vert \geq (1-\varepsilon )\vert a-\lambda _0\mathbf {1}\vert$. A corollary of this result is that for any derivation $ \delta $ on $ \mathcal {M}$ with the range in an ideal $ I\subseteq \mathcal {M}$, the derivation $ \delta $ is inner, that is, $ \delta (\cdot )=\delta _a(\cdot )=[a,\cdot ]$, and $ a\in I$. Similar results are also obtained for inner derivations on $ S(\mathcal {M})$.

References [Enhancements On Off] (What's this?)

Similar Articles

Retrieve articles in Transactions of the American Mathematical Society with MSC (2010): 46L57, 46L51, 46L52

Retrieve articles in all journals with MSC (2010): 46L57, 46L51, 46L52

Additional Information

A. F. Ber
Affiliation: Department of Mathematics, Tashkent State University, Uzbekistan

F. A. Sukochev
Affiliation: School of Mathematics and Statistics, University of New South Wales, Sydney, NSW 2052, Australia

Keywords: Derivations in von Neumann algebras, measurable operators, ideals of compact operators
Received by editor(s): November 18, 2010
Received by editor(s) in revised form: February 15, 2011
Published electronically: May 21, 2012
Article copyright: © Copyright 2012 American Mathematical Society
The copyright for this article reverts to public domain 28 years after publication.