Derivations on Banach $*$-ideals in von Neumann algebras
A. F. Bera,
V. I. Chilinb,
F. A. Sukochevc a Institute of Mathematics of Republica of Uzbekistan
b National University of Uzbekistan
c University of New South Wales, School of Mathematics and Statistics
Abstract:
It is known that any derivation
$\delta: \mathcal M \to \mathcal M$ on the von Neumann algebra
$\mathcal M$ is an inner, i. e.
$\delta(x) := \delta_a(x) =[a, x] =ax -xa$,
$x \in \mathcal M$, for some
$a \in \mathcal M$. If
$H$ is a separable infinite-dimensional complex Hilbert space and
$\mathcal K(H)$ is a
$C^*$-subalgebra of compact operators in
$C^*$-algebra
$\mathcal B(H)$ of all bounded linear operators acting in
$H$, then any derivation
$\delta: \mathcal K(H) \to \mathcal K(H)$ is a spatial derivation, i.e. there exists an operator
$ a \in \mathcal B(H)$ such that
$\delta(x) = [x, a]$ for all
$x \in K(H)$. In addition, it has recently been established by Ber A. F., Chilin V. I., Levitina G. B. and Sukochev F. A. (JMAA, 2013) that any derivation
$\delta: \mathcal{E}\to \mathcal{E}$ on Banach symmetric ideal of compact operators
$\mathcal{E} \subseteq \mathcal K(H)$ is a spatial derivation. We show that the same result is also true for an arbitrary Banach
$*$-ideal in every von Neumann algebra
$\mathcal{M}$. More precisely: If
$\mathcal{M}$ is an arbitrary von Neumann algebra,
$\mathcal{E}$ be a Banach
$*$-ideal in
$\mathcal{M}$ and
$\delta\colon \mathcal{E}\to \mathcal{E}$ is a derivation on
$\mathcal{E}$, then there exists an element
$ a \in \mathcal{M}$ such that
$\delta(x) = [x, a]$ for all
$x \in \mathcal{E}$, i. e.
$\delta $ is a spatial derivation.
Key words:
von Neumann algebra, Banach $*$-ideal, derivation, spatial derivation.
UDC:
517.98
MSC: 46L57,
46L51,
46L52 Received: 21.03.2018
Language: English
DOI:
10.23671/VNC.2018.2.14715