On the Essential Spectrum of a Class of
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Manfred MΓΆller
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Article
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1998
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John Wiley and Sons
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English
β 513 KB
Abrtract. Sufficient conditions are given such that the product T1T2 of two unbounded operators in Hilbert spaces is essentially selfadjoint and that the nonzero numbers in the essential spectrum of the closure of TlT2 coincide with the nonzero numbers in the essential spectrum of T2T1. If the essen