© 1998 by London Mathematical Society
© The London Mathematical Society
Derivations with a Hereditary Domain
Departamento de Analisis Matematico, Facultad de Ciencias, Universidad de Granada 18071 Granada, Spain. E-mail: avillena{at}goliat.ugr.es
Received 7 January 1996. Revision received 19 March 1996.
We investigate the closability of those derivations D defined on a (non necessarily closed) subalgebra B of a complex Banach algebra A for which the conditions
BAB
B and dim[Bk
Rad(A)]<
hold for some k
N, where Rad(A) stands for the Jacobson radical of A. In this situation we show that the separating subspace Y(D) for D satisfies the property
B[B
Y(D)]B
Rad(A).
Furthermore, we demonstrate several specially relevant situations in which we get a closability property which is more precise than the former one.