Derivable mappings at unit operator on nest algebras Original Research Article

Let image be an operator subalgebra with the unit operator I in B(H). We say that a linear mapping φ from image into itself is a derivable mapping at I if φ(ST)=φ(S)T+Sφ(T) for any image with ST = I. In this paper, we show the following main result: every strongly operator topology continuous derivable mapping at I on a nest algebra image is an inner derivation.