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 |