Abstract
We consider quasi-self-adjoint extensions of the symmetric operator \( A = - (\operatorname{sgn} x)\frac{{d^2 }} {{dx^2 }},dom(A) = \{ f \in W_2^2 (\mathbb{R}):f(0) = f'(0) = 0\} \), in the Hilbert space L 2(ℝ). The main result is a criterion of similarity to a normal operator for operators of this class. The spectra and resolvents of these extensions are described. As an application we describe the main spectral properties of the operators \( (\operatorname{sgn} x)\left( { - \tfrac{{d^2 }} {{dx^2 }} + c\delta } \right)and (\operatorname{sgn} x)\left( { - \tfrac{{d^2 }} {{dx^2 }} + c\delta '} \right) \).
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Karabash, I., Kostenko, A. (2007). Spectral Analysis of Differential Operators with Indefinite Weights and a Local Point Interaction. In: Förster, KH., Jonas, P., Langer, H., Trunk, C. (eds) Operator Theory in Inner Product Spaces. Operator Theory: Advances and Applications, vol 175. Birkhäuser Basel. https://doi.org/10.1007/978-3-7643-8270-4_10
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DOI: https://doi.org/10.1007/978-3-7643-8270-4_10
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