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Über Operatoren, die bedingte Basen in einem Hilbertraum erzeugen. (Russian) Zbl 0247.46037


MSC:

46B15 Summability and bases; functional analytic aspects of frames in Banach and Hilbert spaces
46C05 Hilbert and pre-Hilbert spaces: geometry and topology (including spaces with semidefinite inner product)
47A10 Spectrum, resolvent