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Proceedings of the American Mathematical Society

Published by the American Mathematical Society since 1950, Proceedings of the American Mathematical Society is devoted to shorter research articles in all areas of pure and applied mathematics.

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

The 2020 MCQ for Proceedings of the American Mathematical Society is 0.85.

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On iterated similarities of operators
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by Domingo A. Herrero PDF
Proc. Amer. Math. Soc. 72 (1978), 519-520 Request permission

Abstract:

Let $\mathcal {L}(\mathcal {H})$ be the algebra of operators on a complex Hilbert space $\mathcal {H}$. If $A \in \mathcal {L}(\mathcal {H})$ is invertible and $\{ X \in \mathcal {L}(\mathcal {H}):\left \|{A^k}X{A^{ - k}}\right \| \leqslant C(X) < \infty ,k = 0,1,2, \ldots \}$ coincides with $\mathcal {L}(\mathcal {H})$, then A is a multiple of a similarity of a unitary operator.
References
    J. A. Deddens, Another characterization of nest algebras (preprint).
  • Shôichirô Sakai, $C^*$-algebras and $W^*$-algebras, Ergebnisse der Mathematik und ihrer Grenzgebiete, Band 60, Springer-Verlag, New York-Heidelberg, 1971. MR 0442701
  • Béla de Sz. Nagy, On uniformly bounded linear transformations in Hilbert space, Acta Univ. Szeged. Sect. Sci. Math. 11 (1947), 152–157. MR 22309
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Additional Information
  • © Copyright 1978 American Mathematical Society
  • Journal: Proc. Amer. Math. Soc. 72 (1978), 519-520
  • MSC: Primary 47A65
  • DOI: https://doi.org/10.1090/S0002-9939-1978-0509246-3
  • MathSciNet review: 509246