K. V. Pozharska | Searcharxiv

arXiv2024

Estimates for the approximation characteristics of the Nikol'skii-Besov classes of functions with mixed smoothness in the space $B_{q,1}$

Exact-order estimates are obtained for some approximation characteristics of the classes of periodic multivariate functions with mixed smoothness (the Nikol'skii-Besov classes $B^{\boldsymbol{r}}_{p, θ}$) in the space $B_{q,1}$, $1 \leq p, q \leq \infty$, which norm is stronger than the $L_q$-norm. It is shown, that in the multivariate case (in contrast to the univariate) in most of the considered situations the obtained estimates differ in order from the corresponding estimates in the space $L_q$. Besides, a significant progress is made in estimates for the considered approximation characteristics of the classes $B^{\boldsymbol{r}}_{p, θ}$ in the space $B_{q, 1}$ comparing to the known estimates in the space $L_q$.

math.CA↗

arXiv2024

Best approximations for classes of periodic functions of many variables with bounded dominating mixed derivative

We established exact in order estimates an approximation of the Sobolev classes $W^{\boldsymbol{r}}_{p,\boldsymbolα}(\mathbb{T}^d)$ of periodic functions of many variables with a bounded dominating mixed derivative. The approximation is made using trigonometric polynomials with the spectrum in step-hyperbolic crosses, and the error is estimated in the metric of the space $B_{q,1}(\mathbb{T}^d)$, $1 \leqslant p, q < \infty$.

math.CA↗