设R(H)是复Hilbert空间形上的有界线性算子全体且dim H≥2.本文证明了R(H)上的线性满射φ保持两个算子乘积非零投影性的充分必要条件是存在R(H)中的酉算子U以及复常数λ满足λ^2=1,使得φ(x)=λU*XU, X∈R(H).同时也得到了线性映射保持两个算子Jordan三乘积非零投影的充分必要条件.
Let R(H) be the algebra of all bounded linear operators on a complex Hilbert space H with dim H ≥ 2. It is proved that a linear surjective map φ on R(H) preserves the nonzero projections of products of two operators if and only if there is a unitary operator U in R(H) such that φ(x)=λU*XU, X∈R(H) for some constants λ with ,λ^2 = 1. Related results for linear surjective maps preserving Jordan triple products of two operators are also obtained.