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REFINEMENTS OF THE NORM OF TWO ORTHOGONAL PROJECTIONS
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作者 Xiaohui LI Meiqi LIU Chunyuan DENG 《Acta Mathematica Scientia》 SCIE CSCD 2024年第4期1229-1243,共15页
In this paper,some refinements of norm equalities and inequalities of combination of two orthogonal projections are established.We use certain norm inequalities for positive contraction operator to establish norm ineq... In this paper,some refinements of norm equalities and inequalities of combination of two orthogonal projections are established.We use certain norm inequalities for positive contraction operator to establish norm inequalities for combination of orthogonal projections on a Hilbert space.Furthermore,we give necessary and sufficient conditions under which the norm of the above combination of o`rthogonal projections attains its optimal value. 展开更多
关键词 NORM orthogonal projection positive operator SPECTRAL block operator valued matrix
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Furi-Martelli-Vignoli spectrum and Feng spectrum of nonlinear block operator matrices 被引量:1
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作者 Xiao-Mei Dong De-Yu Wu Alatancang Chen 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第4期130-138,共9页
We investigate the Furi-Martelli-Vignoli spectrum and the Feng spectrum of continuous nonlinear block operator matrices,and mainly describe the relationship between the Furi-Martelli-Vignoli spectrum(compared to the F... We investigate the Furi-Martelli-Vignoli spectrum and the Feng spectrum of continuous nonlinear block operator matrices,and mainly describe the relationship between the Furi-Martelli-Vignoli spectrum(compared to the Feng spectrum)of the whole operator matrix and that of its entries.In addition,the connection between the Furi-Martelli-Vignoli spectrum of the whole operator matrix and that of its Schur complement is presented by means of Schur decomposition. 展开更多
关键词 nonlinear operator SPECTRUM block operator matrix
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HYPONORMALITY OF BLOCK TOEPLITZ OPERATORS ON THE WEIGHTED BERGMAN SPACES 被引量:1
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作者 Jongrak LEE 《Acta Mathematica Scientia》 SCIE CSCD 2017年第6期1695-1704,共10页
In this paper we consider the block Toeplitz operators TФ on the weighted Bergman space A2α(D, Cn) and we give a necessary and sufficient condition for the hyponor-mality of block Toeplitz operators with symbol in... In this paper we consider the block Toeplitz operators TФ on the weighted Bergman space A2α(D, Cn) and we give a necessary and sufficient condition for the hyponor-mality of block Toeplitz operators with symbol in the class of functions Ф=F + G* withmatrix-valued polynomial functions F and G with degree 2. 展开更多
关键词 block Toeplitz operators hyponormal weighted Bergman space
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Block dual Toeplitz Operators on the Orthogonal Complements of Fock Spaces
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作者 Jian Xiang DONG Chun Xu XU Yu Feng LU 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2024年第8期1967-1988,共22页
In this paper,we characterize the boundedness and compactness of the block dual Toeplitz operators acting on the orthogonal complement of the Fock spaces,and the compactness of the finite sum of two dual Toeplitz oper... In this paper,we characterize the boundedness and compactness of the block dual Toeplitz operators acting on the orthogonal complement of the Fock spaces,and the compactness of the finite sum of two dual Toeplitz operators products.The commutator and semi-commutator induced by the block dual Toeplitz operators are considered. 展开更多
关键词 block dual Toeplitz operators BOUNDEDNESS COMPACTNESS Fock space (semi)-commutator
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On the Adjoint of Operator Matrices with Unbounded Entries II
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作者 De Yu WU Alatancang CHEN 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2015年第6期995-1002,共8页
In this paper, the adjoint of a densely defined block operator matrix L=[A B C D] in a Hilbert space X ×X is studied and the sufficient conditions under which the equality L*=[A* B* C* D*] holds are obtained... In this paper, the adjoint of a densely defined block operator matrix L=[A B C D] in a Hilbert space X ×X is studied and the sufficient conditions under which the equality L*=[A* B* C* D*] holds are obtained through applying Frobenius-Schur factorization. 展开更多
关键词 block operator matrix adjoint operator Frobenius-Schur factorization
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