On conditions that the spectra of certain operators be discrete

M. A. Shubin

M. V. Lomonosov Moscow State University

Abstract: Certain necessary and sufficient conditions for the discreteness of the spectrum of an operator are obtained in terms of its symbol and also in terms of its Wick and anti-Wick symbol.

UDC: 513.88

Received: 07.01.1971

 English version: Mathematical Notes, 1972, 11:3, 147–151

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