Best “Continuous” $n$-Term Approximations in the Spaces $S_\phi ^p$
We find exact values of upper bounds for the best approximations of $q$-ellipsoids by polynomials of degree $n$ in the spaces $S_\phi ^p$ in the case where the approximating polynomials are constructed on the basis of $n$-dimensional subsystems chosen successively from a given orthonormal system ϕ.
English version (Springer): Ukrainian Mathematical Journal 55 (2003), no. 5, pp 801–811.
Citation Example: Rukasov V. I., Stepanets O. I. Best “Continuous” $n$-Term Approximations in the Spaces $S_\phi ^p$ // Ukr. Mat. Zh. - 2003. - 55, № 5. - pp. 663-670.