On subnormal operators whose spectrum are multiply connected domains.
Carlsson, M. (2011)
The New York Journal of Mathematics [electronic only]
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Carlsson, M. (2011)
The New York Journal of Mathematics [electronic only]
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Laurian Suciu (2006)
Extracta Mathematicae
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Some invariant subspaces for the operators A and T acting on a Hilbert space H and satisfying T*AT ≤ A and A ≥ 0, are presented. Especially, the largest invariant subspace for A and T on which the equality T* AT = A occurs, is studied in connections to others invariant or reducing subspaces for A, or T. Such subspaces are related to the asymptotic form of the subspace quoted above, this form being obtained using the operator limit of the sequence {TAT; n ≥ 1}. More complete results are...
Ahdout, Shahla, Rothman, Sheldon (2006)
Revista Colombiana de Matemáticas
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Bachir, A., Segres, A. (2009)
International Journal of Open Problems in Computer Science and Mathematics. IJOPCM
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Mecheri, S. (2003)
Acta Mathematica Universitatis Comenianae. New Series
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Pankov, Mark (2004)
Beiträge zur Algebra und Geometrie
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László Kérchy (1994)
Banach Center Publications
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In this survey article we are going to present the effectiveness of the use of unitary asymptotes in the study of Hilbert space operators.
Kowynia, Joanna (2005)
Zeszyty Naukowe Uniwersytetu Jagiellońskiego. Universitatis Iagellonicae Acta Mathematica
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Castejón, A., Corbacho, E., Tarieladze, V. (2002)
Georgian Mathematical Journal
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Kirchev, Kiril, Borisova, Galina (2005)
Serdica Mathematical Journal
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2000 Mathematics Subject Classification: Primary 47A48, Secondary 60G12. In this paper classes of K^r -operators are considered – the classes of bounded and unbounded operators A with equal domains of A and A*, finite dimensional imaginary parts and presented as a coupling of a dissipative operator and an antidissipative one with real absolutely continuous spectra and the class of unbounded dissipative K^r -operators A with different domains of A and A* and with real absolutely...
George A. Anastassiou, Heinz H. Gonska (1995)
Annales Polonici Mathematici
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In recent papers the authors studied global smoothness preservation by certain univariate and multivariate linear operators over compact domains. Here the domain is ℝ. A very general positive linear integral type operator is introduced through a convolution-like iteration of another general positive linear operator with a scaling type function. For it sufficient conditions are given for shift invariance, preservation of global smoothness, convergence to the unit with rates, shape preserving...
Yves Raynaud (2004)
Revista Matemática Complutense
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We show that the range of a contractive projection on a Lebesgue-Bochner space of Hilbert valued functions L(H) is isometric to a l-direct sum of Hilbert-valued L-spaces. We explicit the structure of contractive projections. As a consequence for every 1 < p < ∞ the class C of l-direct sums of Hilbert-valued L-spaces is axiomatizable (in the class of all Banach spaces).
Engliš, Miroslav (2005)
Journal of Lie Theory
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