© 1999 by London Mathematical Society
© The London Mathematical Society
Skew Derivations with Central Invariants
Department of Mathematics, DePaul University Chicago, IL 60614 USA. E-mail: jbergen{at}condor.depaul.edu
Institute of Mathematics, University of Bia
ystok 15-267, Bia
ystok, Poland. E-mail: piotrgr{at}cksr.ac.bialystok.pl
Received 3 December 1995. Revision received 30 June 1996.
If
is an automorphism and
is a
-derivation of a ring R, then the subring of invariants is the set R(
)={r
R|
(r)=0}. The main result of this paper is let R be a semiprime ring with an algebraic
-derivation
such that R(
) is central; then R is commutative. This theorem generalizes results on the invariants of automorphisms and derivations and is proved by reducing down to the special cases of automorphisms and derivations.