We propose a criterion of transversality and disjointness for the Friedrichs and Krein extensions of a nonnegative symmetric operator in terms of the vectors {φj, j ϵ 𝕁} that form a Riesz basis of the defect subspace. The criterion is applied to the Friedrichs and Krein extensions of the minimal Schrödinger operator Ad with point potentials. We also present a new proof of the fact that the Friedrichs extension of the operator Ad is a free Hamiltonian.
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Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 70, No. 4, pp. 495–505, April, 2018.
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Kovalev, Y.G. On the Criteria of Transversality and Disjointness of Nonnegative Self-Adjoint Extensions of Nonnegative Symmetric Operators. Ukr Math J 70, 568–580 (2018). https://doi.org/10.1007/s11253-018-1517-9
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DOI: https://doi.org/10.1007/s11253-018-1517-9