|Dopov. Nac. akad. nauk Ukr. 2017, 3:3-7|
We obtain the necessary and sufficient conditions of unconditional basicity of functions that are solutions of second-order equations (Bessel-type), and the spectral parameter belongs to a discrete set coinciding with the zeros of an entire function of the exponential type.
|Keywords: basicity, Bernstein class, Bessel equation, Hilbert space, operator, real function, unconditional basis|
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