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Generalized numerical radius of a bounded linear operator

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Abstract

In this paper, we considered the generalized numerical radius of a bounded linear operator defined from a Hilbert space H into itself and derived certain basic properties of generalized numerical radius of normal and hyponormal operators. We then concentrate on nilpotent operators and operators that are involutions and idempotents and present estimates for the generalized numerical radius. We also considered several examples to illustrate our results.

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References

  1. Abu-Omar, A., Kittaneh, F.: A generalization of the numerical radius. Linear Algebra Appl. 428(7), 1460–1475 (2008)

    MathSciNet  Google Scholar 

  2. Bottazzi, T., Conde, C.: Generalized numerical radius and related inequalities. Oper. Matrices 15(4), 1289–1308 (2021)

    Article  MathSciNet  MATH  Google Scholar 

  3. Bhunia, P., Dragomir, S.S., Moslehian, M.S., Paul, K.: Lectures on Numerical Radius Inequalities. Infosys Science Foundation Series in Mathematical Sciences. Springer, Cham (2022). ISBN:978-3-031-13669-6; 978-3-031-13670-2

  4. Bhunia, P., Feki, K., Paul, K.: Generalized A-numerical radius of operators and related inequalities. Bull. Iran. Math. Soc. 48, 3883–3907 (2022)

    Article  MathSciNet  MATH  Google Scholar 

  5. Douglas, R.G.: Banach Algebra Techniques in Operator Theory. Academic Press, New York (1972)

    MATH  Google Scholar 

  6. Douglas, R.G.: On majorization, factorization, and range inclusion of operators on Hilbert space. Proc. Am. Math. Soc. 17(2), 413–415 (1966)

    Article  MathSciNet  MATH  Google Scholar 

  7. Dragomir, S.S.: The hypo-Euclidean norm of an n-tuple of vectors in inner product spaces and applications. J. Inequal. Pure Appl. Math. 8(2), 52 (2007)

  8. Fujii, M., Furuta, T., Kamei, E.: Furuta’s inequality and its application to Ando’s theorem. Linear Algebra Appl. 179, 161–169 (1993)

    Article  MathSciNet  MATH  Google Scholar 

  9. Furuta, T.: Applications of order preserving operator inequalities. In: Operator Theory and Complex Analysis (Sapporo, 1991). Operator Theory: Advances and Applications, vol. 59, pp. 180–190. Birkhäuser, Basel (1992)

  10. Gustafson, K.E., Rao, D.K.M.: Numerical Range. The Field of Values of Linear Operators and Matrices. Universitext, Springer, New York (1997)

    Google Scholar 

  11. Halmos, P.R.: A Hilbert Space Problem Book. Van Nostrand, Princeton (1967)

    MATH  Google Scholar 

  12. Kittaneh, F.: Notes on some inequalities for Hilbert space operators. Publ. Res. Inst. Math. Sci. 24(2), 283–293 (1988)

    Article  MathSciNet  MATH  Google Scholar 

  13. Mortad, M.H.: An application of the Putnam–Fuglede theorem to normal products of self-adjoint operators. Proc. Am. Math. Soc. 131, 3135–3141 (2003)

    Article  MathSciNet  MATH  Google Scholar 

  14. Mortad, M.H.: Counterexamples in Operator Theory. Birkhäuser/Springer, Cham (2022). ISBN:978-3-030-97813-6; 978-3-030-97814-3

  15. Moslehian, M.S., Nazafi, H.: An extension of the Löwner–Heinz inequality. Linear Algebra Appl. 437(9), 2359–2365 (2012)

    Article  MathSciNet  MATH  Google Scholar 

  16. Tanahashi, K.: On log-hyponormal operators. Integral Equ. Oper. Theory 34(3), 364–372 (1999)

    Article  MathSciNet  MATH  Google Scholar 

  17. Uchiyama, M.: Operators which have commutative polar decomposition. In: Contributions to Operator Theory and its Applications: The Tsuyoshi Ando Anniversary Volume, pp. 197–208 (1993)

  18. Yamazaki, T.: On upper and lower bounds of the numerical radius and an equality condition. Stud. Math. 178, 83–89 (2007)

    Article  MathSciNet  MATH  Google Scholar 

  19. Zamani, A., Moslehian, M.S., Xu, Q., Fu, C.: Numerical radius inequalities concerning with algebra norms. Mediterr. J. Math. 18(2), 1–13 (2021)

    Article  MathSciNet  MATH  Google Scholar 

  20. Zamani, A., Wojcik, P.: Another generalization of the numerical radius for Hilbert space operators. Linear Algebra Appl. 609, 114–128 (2021)

    Article  MathSciNet  MATH  Google Scholar 

  21. Zhang, F.: On the Bohr inequality of operators. J. Math. Anal. Appl. 333, 1264–1271 (2007)

    Article  MathSciNet  MATH  Google Scholar 

  22. Zhu, K.: Operator Theory in Function Spaces. Marcel Dekker, Inc., New York (1990)

    MATH  Google Scholar 

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Acknowledgements

The authors thank the referee and the editor for the valuable suggestions and comments on an earlier version. Incorporating appropriate responses to these in the article has led to a better presentation of the results.

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Correspondence to Mamata Rani Jena.

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Communicated by Yiu-Tung Poon.

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Das, N., Jena, M.R. Generalized numerical radius of a bounded linear operator. Adv. Oper. Theory 8, 62 (2023). https://doi.org/10.1007/s43036-023-00289-3

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