International Journal of Mathematics and Mathematical Sciences
Volume 13 (1990), Issue 1, Pages 135-138
doi:10.1155/S0161171290000175
A note on one-parameter groups of automorphisms
Department of Mathematics, Quiad-i-Azam University, Islamabad, Pakistan
Received 7 July 1988; Revised 1 September 1988
Copyright © 1990 A. B. Thaheem and Noor Mohammad. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Let {αt:t∈R} and {βt:t∈R} be two commuting one-parameter groups of ∗-automorphisms of a von Neumann algebra M such that αt+α−t=βt+β−t for all t∈R. The purpose of this note is to provide a simple and short proof of the central decomposition result: αt=βt on Mp and a αt=β−t on M(1−p) for a central projection p∈M, without using the theory of spectral subspaces.