ON COMMUTATIVITY OF BANACH ALGEBRAS WITH DERIVATIONS

Abstract

The aim of this paper is to discuss the commutativity of a Banach algebra $A$ via its derivations. In particular, we prove that if $A$ is a unital prime Banach algebra and $A$ has a nonzero continuous linear derivation $d:A\rightarrow A$ such that either $d((xy)^{m})-x^{m}y^{m}$ or $d((xy)^{m})-y^{m}x^{m}$ is in the centre of $A$ for an integer $m=m(x,y)$ and sufficiently many $x,y$, then $A$ is commutative. We give examples to illustrate the scope of the main results and show that the hypotheses are not superfluous.