One inequality of the Landau – Kolmogorov type for periodic functions of two variable

• Date: 2019
• Main Authors: Babenko, V. F., Бабенко, В. Ф.
• Format: Article
• Language: Russian
• Published: Institute of Mathematics, NAS of Ukraine 2019
• Online Access: https://umj.imath.kiev.ua/index.php/umj/article/view/1428
• Journal Title: Ukrains’kyi Matematychnyi Zhurnal

We obtain a new sharp inequality of the Landau – Kolmogorov type for a periodic function of two variables that estimates the convolution of the best uniform approximations of its partial primitives by the sums of univariate functions with the help of its $L_{\infty}$ -norm and uniform norms of its m...