Abstract
For the case of a simply connected domain in the plane one proves necessary and sufficient conditions for the representation of functions of the Hardy class H1 by an integral with respect to the harmonic measure of its boundary values. A theorem is given, characterizing the rate of decrease of the best polynomial approximations of an entire function in Hardy classes by the order and the type of this function.
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Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 3, pp. 342–347, March, 1991.
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Dovgoshei, A.A. Integral representations in Hardy classes and best approximations in certain functional spaces. Ukr Math J 43, 306–311 (1991). https://doi.org/10.1007/BF01670070
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DOI: https://doi.org/10.1007/BF01670070