Proceedings of the American Mathematical Society

ISSN 1088-6826(online) ISSN 0002-9939(print)



Operator versions of the Kantorovich inequality

Author: P. G. Spain
Journal: Proc. Amer. Math. Soc. 124 (1996), 2813-2819
MSC (1991): Primary 47A63; Secondary 15A45, 65F65
MathSciNet review: 1328379
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Abstract: The Operator Kantorovich Inequality

\begin{displaymath}(R^2 - r^2) \, u^* (a^* a) \, u \ \le \ R^2 \, (u^* a^* u) (u^* a u) \end{displaymath}

holds for a wide class of operators $a$ on a Hilbert space $\mathcal {H}$ and all operators $u: % \mathcal {K}\to % \mathcal {H}$ for which $[a] \, u$ is a partial isometry, $[a]$ being the range projection of $a.$

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Additional Information

P. G. Spain
Affiliation: Department of Mathematics, University of Glasgow, Glasgow G12 8QW, Scotland

Keywords: Kantorovich Inequality, Cauchy-Schwarz Inequality
Received by editor(s): March 23, 1995
Communicated by: Palle E. T. Jorgensen
Article copyright: © Copyright 1996 American Mathematical Society