79 citations · 210 across the 18 of their papers we have counts for
9 papers · 1 filter
Norm attainment of a class of block operator matrices
Kangjian Wu, Jiayu Ling, Qingxiang Xu
Given complex numbers and a non-negative continuous function defined on , consider the matrix $$ M_t = \begin{pmatrix} a & t \\ ct & bφ(t)…
The polar decomposition of the product of three operators
Dingyi Du, Qingxiang Xu, Shuo Zhao
In the setting of adjointable operators on Hilbert -modules, this paper deals with the polar decomposition of the product of three operators. The relationship between the pola…
Some upper bounds for the -numerical radius of block matrices
Qingxiang Xu, Zhongming Ye, Ali Zamani
Let be the diagonal operator matrix determined by a positive bounded operator . For semi-H…
Seminorm and numerical radius inequalities of operators in semi-Hilbertian spaces
M. S. Moslehian, Q. Xu, A. Zamani
Let be a positive bounded operator on a Hilbert space . The semi-inner product ${\langle x, y\rangle}_A := \langle Ax, y\ra…
Numerical radius inequalities concerning with algebraic norms
A. Zamani, M. S. Moslehian, Q. Xu +1
We give an expression for a generalized numerical radius of Hilbert space operators and then apply it to obtain upper and lower bounds for the generalized numerical radius. We also…
Halmos' two projections theorem for Hilbert -module operators and the Friedrichs
Wei Luo, Mohammad Sal Moslehian, Qingxiang Xu
Halmos' two projections theorem for Hilbert space operators is one of the fundamental results in operator theory. In this paper, we introduce the term of two harmonious projections…
Positivity of block matrices of operators
Mohammad Sal Moslehian, Mohsen Kian, Qingxiang Xu
We review some of the significant generalizations and applications of the celebrated Douglas theorem on the equivalence of factorization, range inclusion, and majorization of opera…
New multiplicative perturbation bounds for the generalized polar decomposition
Na Liu, Wei Luo, Qingxiang Xu
Some new Frobenius norm bounds of the unique solution to certain structured Sylvester equation are derived. Based on the derived norm upper bounds, new multiplicative perturbation…
Perturbation estimation for the parallel sum of Hermitian positive semi-definite matrices
Wei Luo, Chuanning Song, Qingxiang Xu
Let be the set of all complex matrices. For any Hermitian positive semi-definite matrices and in , their new c…