Norm-Attainability and Range-Kernel Orthogonality of Elementary Operators
Abstract
Various aspects of elementary operators have been characterized by many mathematicians. In this paper, we consider norm-attainability and orthogonality of these operators in Banach spaces. Characterizations and generalizations of norm-attainability and orthogonality are given in details. We first give necessary and sufficient conditions for norm-attainability of Hilbert space operators then we give results on orthogonality of the range and the kernel of elementary operators when they are implemented by norm-attainable operators in Banach spaces.
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References
- [1] C. Benitez, Orthogonality in normed linear spaces: a classification of the different concepts and some open problems, Rev. Mat., 2 (1989), 53-57.
- [2] J. Anderson, On normal derivations, Proc. Amer. Math. Soc., 38 (1973), 135-140.
- [3] F. Kittaneh, Normal derivations in normal ideals, Proc. Amer. Math. Soc., 6 (1995), 1979-1985.
- [4] S. Mecheri, On the range and kernel of the elementary operators $\sum_{i=1}^{n}A_{i}XB_{i}-X$}, Acta Math. Univ. Comnianae, 52 (2003), 119-126.
- [5] A. Bachir, A. Segres, Numerical range and orthogonality in normed spaces, Filomat, 23 (2009), 21-41.
- [6] G. Bachman, L. Narici, Functional Analysis, Academic press, New York, 2000.
- [7] D. K. Bhattacharya, A. K. Maity, Semilinear tensor product of $\Gamma$- Banach algebras, Ganita, 40(2) (1989), 75-80.
- [8] F. Bonsall, J. Duncan, Complete Normed Algebra, Springer Verlag, New York, 1973.
- [9] J. O. Bonyo, J. O. Agure, Norm of a derivation and hyponormal operators, Int. J. Math. Anal., 4(14) (2010), 687-693.
- [10] S. Bouali, Y. Bouhafsi, On the range of the elementary operator $X\mapsto AXA-X$, Math. Proc. R. Ir. Acad., 108 (2008), 1-6.
