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A generalisation of the inverse spectral theorem of Levitan and Gasymov

Published online by Cambridge University Press:  14 November 2011

Christine Thurlow
121 The Grove, Ealing, London W5


In the Inverse Spectral Theorem in the form given by Levitan and Gasymov, necessary and sufficient conditions are given for a non-decreasing function, p(ℷ), to be the spectral function of a Sturm–Liouville problem. In these conditions, p(ℷ) is compared with the spectral function for the particular Strum–Liouville problem

If the method of Levitan and Gasymov's proof is slightly adapted, the necessary and sufficient conditions can be stated in a more general form in which p(ℷ) is compared with the spectral function for any problem of the form

where hO is real and qo(x) locally integrable.

Research Article
Copyright © Royal Society of Edinburgh 1979

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