Exact values of the best (α, β) -approximations of classes of convolutions with kernels that do not increase the number of sign changes

• Date: 2017
• Main Authors: Parfinovych, N. V., Парфинович, Н. В.
• Format: Article
• Language: Russian
• Published: Institute of Mathematics, NAS of Ukraine 2017
• Online Access: https://umj.imath.kiev.ua/index.php/umj/article/view/1759
• Journal Title: Ukrains’kyi Matematychnyi Zhurnal

We obtain the exact values of the best $(\alpha , \beta )$-approximations of the classes $K \ast F$ of periodic functions $K \ast f$ such that $f$ belongs to a given rearrangement-invariant set $F$ and $K$ is $2\pi$ -periodic kernel that do not increase the number of sign changes by the subspaces...