علی تقوی

Let H be a complex Hilbert space and B(H) denotes the algebra of all bounded linear operators on H. Suppose that  : B(H) 􀀀! B(H) is an additive surjective map. We prove that if  satis es (A)(P) = (P)(A) if and only if AP = PA for  2 f1;􀀀1g and for all A and idempotent P in B(H), then  is a *-automorphism.