We obtain exact order estimates for trigonometric and orthoprojection widths of the Besov classes B r p,θ and Nikol’skii classes Hr p of periodic functions of many variables in the space L q for certain relations between the parameters p and q.
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Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 61, No. 10, pp. 1348–1366, October, 2009.
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Romanyuk, A.S., Romanyuk, V.S. Trigonometric and orthoprojection widths of classes of periodic functions of many variables. Ukr Math J 61, 1589–1609 (2009). https://doi.org/10.1007/s11253-010-0300-3
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DOI: https://doi.org/10.1007/s11253-010-0300-3