Maps preserving numerical ranges of operator products
نویسندگان
چکیده
منابع مشابه
Linear Maps Preserving the Higher Numerical Ranges of Tensor Products of Matrices
For a positive integer n, let Mn be the set of n×n complex matrices. Suppose m,n ≥ 2 are positive integers and k ∈ {1, . . . ,mn− 1}. Denote by Wk(X) the k-numerical range of a matrix X ∈Mmn. It is shown that a linear map φ : Mmn →Mmn satisfies Wk(φ(A⊗B)) = Wk(A⊗B) for all A ∈Mm and B ∈Mn if and only if there is a unitary U ∈Mmn such that one of the following holds. (i) For all A ∈Mm, B ∈Mn, φ(...
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ژورنال
عنوان ژورنال: Proceedings of the American Mathematical Society
سال: 2005
ISSN: 0002-9939
DOI: 10.1090/s0002-9939-05-08101-3