We establish the exact-order estimates for the best bilinear approximations of the Nikol’skii–Besov classes \( {B}_{\mathrm{p},\theta}^{\mathrm{r}} \) of periodic functions of several variables. We also determine the orders of singular numbers for the integral operators with kernels from the classes \( {B}_{\mathrm{p},\theta}^{\mathrm{r}} \).
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Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 68, No. 9, pp. 1240–1250, September, 2016.
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Romanyuk, A.S., Romanyuk, V.S. Estimation of the Best Linear Approximations for the Classes \( {B}_{\mathrm{p},\theta}^{\mathrm{r}} \) and Singular Numbers of the Integral Operators. Ukr Math J 68, 1424–1436 (2017). https://doi.org/10.1007/s11253-017-1304-z
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DOI: https://doi.org/10.1007/s11253-017-1304-z