• Journal of applied mathematics & informatics
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• v.4 no.2
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• pp.555-561
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• 1997

In this paper we show that if A is a Banach algebra with radical R and D is a left derivation on A then $D(A){\subset}R$ if and only if $Q_RD^n$ is continuous for all $n{\geq}1$, where $Q_R$ is the canonical quotient map from A onto A/R.