Norm Properties of $S$-Universal Operators

Norm Properties of $S$-Universal Operators

We investigate the norm properties of a generalized derivation on a norm ideal $\mathcal{J}$ in $\mathcal{B}(H)$, the algebra of bounded linear operators on a Hilbert space $H$. Specifically, we extend the concept of $S-$universality from the inner derivation to the generalized derivation context, establish the necessary conditions for the attainment of the optimal value of the circumdiameters of numerical ranges and the spectra of two bounded linear operators on $H$. Moreover, we characterize the antidistance from an operator to its similarity orbit in terms of the circumdiameters, norms, numerical and spectra radii of a pair of $S$-universal operators.

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  • [1] J. G. Stampfli, The norm of a derivation, Pac. J. Math. 33 (1970).
  • [2] R. Schatten, Norm ideals of completely continuos operators, Springler-Verlag,Berlin (1960),55-79.
  • [3] L. A. Fialkow, A note on norm ideals and the operator $X\rightarrow AX-XB$, Isr. J. Math., 32 (1979), 331-348.
  • [4] M. Barraa and M. Boumazgour, Inner derivation and norm equality, Proc. Amer. Math. Soc., 130(2) (2001), 471-476.
  • [5] J. O. Bonyo and J. O. Agure, Norms of Derivations Implemented by S-universal Operators, Int. J. Math. Anal., 5(5) (2011), 215-222
  • [6] J. O. Bonyo and J. O. Agure, Norms of Inner Derivations on Norm Ideals, Int. J. Math. Anal., 4 (14)(2010), 695-701.
  • [7] F. Bonsall and J. Duncan, Complete Normed Algebras, Springer-Verlag New York Heidelberg Berlin 1973.
  • [8] A. Pere and M. Martin, Local Multipliers of $C^{*}-Algebras$Algebras, Springer-Verlag, Lodon New York Heidelberg Berlin.
  • [9] S. Y. Shaw, On numerical ranges of generalized derivations and related properties, J. Austral. Math. Soc., 36 (1984), 134-142.
  • [10] C. S. Lin,The Unilateral Shift and a Norm Equality for Bounded Linear Operators, Proc. Amer. Math. Soc., 127 (1999) No. 6, 1693-1696.
  • [11] M. Barraa and S. Pedersen,On the Product of two Generalized Derivations, Proc. Amer. Math. Soc., 127 (1999), 2679-2683.
  • [12] P. Halmos, A Hilbert space problem book, Van Nostrand, Princeton, 1970.
  • [13] T. Ando, Bounds for Anti-distance, J. Convex Anal., 3 (1996) No. 2, 371-373.