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On estimate for numerical radius of some contractions

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Abstract

For the numerical radius of an arbitrary nilpotent operator T on a Hilbert space H, Haagerup and de la Harpe proved the inequality \(w(T) \leqslant \left\| T \right\|cos\frac{\pi }{{n + 1}}\), where n ≥ 2 is the nilpotency order of the operator T. In the present paper, we prove a Haagerup-de la Harpe-type inequality for the numerical radius of contractions from more general classes.

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Authors and Affiliations

  1. Institute of Mathematics and Mechanics, Azerbaijan National Academy of Sciences, Baku, Azerbaijan

    M. T. Karaev

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  1. M. T. Karaev
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Published in Ukrains’kyi Matematychnyi Zhurnal, Vol. 58, No. 10, pp. 1335–1339, October, 2006.

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Karaev, M.T. On estimate for numerical radius of some contractions. Ukr Math J 58, 1512–1516 (2006). https://doi.org/10.1007/s11253-006-0150-1

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  • DOI: https://doi.org/10.1007/s11253-006-0150-1

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