The Quarterly Journal of Mathematics Advance Access originally published online on February 10, 2006
The Quarterly Journal of Mathematics 2006 57(4):469-478; doi:10.1093/qmath/hal003
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
ON A BRE
AR
EMRL CONJECTURE AND DERIVATIONS OF BANACH ALGEBRAS

1 Department of Management and Information Technology, Southern Taiwan University of Technology, Yung-Kang, Tainan 710, Taiwan
2 Department of Mechanics and Mathematics, Tula State University, Tula, Russia
3 Department of Mathematics, National Cheng Kung University, Tainan 701, Taiwan
4 Department of Mathematics, National Taiwan University, Taipei 106, Taiwan
Corresponding author. E-mail: phlee{at}math.ntu.edu.tw
| Abstract |
|---|
In this paper, we answer a question on derivations of dense algebras of linear operators posed by Bre
ar and
emrl. Our theorem implies the following result: let
be a complex Banach algebra, and let d and g be continuous derivations of
. If dg(x) is quasi-nilpotent for every x
, then dg(x)3 lies in the radical of
for every x
. This result was proved by Bre
ar and
emrl with the additional assumption gd = dg.