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In this paper, we present some necessary and sufficient conditions for the existence of solutions, hermitian solutions and positive solutions to the system of operator equations AXB=C=BXA in the setting of bounded linear operators on a Hilbert space. Moreover, we obtain the general forms of solutions, hermitian solutions and positive solutions to the system above. 相似文献
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Let H be a complex Hilbert space and B(H)the algebra of all bounded linear operators on H.An operator A is called the truncation of B in B(H)if A=PABPA*,where PA and PA*denote projections onto the closures of R(A)and R(A*),respectively.In this paper,we determine the structures of all additive surjective maps on B(H)preserving the truncation of operators in both directions. 相似文献
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Let Bs(H) be the real linear space of all self-adjoint operators on a complex Hilbert space H with dim H ≥ 2.It is proved that a linear surjective map on Bs (H) preserves the nonzero projections of Jordan products of two operators if and only if there is a unitary or an anti-unitary operator U on H such that (X)=λU XU,X∈Bs(H) for some constant λ with λ∈{1,1}. 相似文献
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设X是具有无限重复度的无限维或维数不小于3的有限维复Banach空间,B(X)是X上全体有界线性算子组成的Banach代数.首先证明了单位算子不能表示成3个平方幂零算子之和,利用算子分块矩阵技巧获得了平方幂零算子的本质特征.以此特征为基础,刻画了B(X)上双边保持二次算子可加满射的结构. 相似文献
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设H是复Hilbert空间,B(H)是H上的有界线性算子全体组成的代数,M?B(H)是von Neumann代数,"≤"表示M中的*-偏序,即A,B∈M,若A~*A=A~*B,AA~*=BA~*,则A≤B.本文研究了von Neumann代数中*-偏序的上确界和下确界,证明了von Neumann代数M的子集关于*-偏序的上、下确界和B(H)中的上、下确界一致.同时,给出了M的*-偏序遗传子空间的表示,证明了弱~*闭子空间A?M,满足A∈M,B∈A,由A≤B可得A∈A,当且仅当存在唯一具有相同中心投影的投影对E,F∈M,使得A=EMF. 相似文献
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令β是维数大于1的Hilbert空间H上的套,algβ为相应的套代数.k为一非零有理数.本文证明了algβ上的k-Jordan可导映射,即δ(k(ab+ba))=k(δ(a)b+aδ(b)+δ(b)a+bδ(a)),(?)a,b∈algβ,是algβ上的可加导子.特别地,当H是无限维时,δ是内导子.我们也给出了k-Jordan三重可导映射的相应结果. 相似文献