Stechkin-type estimate for nearly copositive approximation of periodic functions

• Date: 2020
• Main Authors: Dzyubenko, G. A., Дзюбенко, Г. А.
• Format: Article
• Language: Ukrainian
• Published: Institute of Mathematics, NAS of Ukraine 2020
• Online Access: https://umj.imath.kiev.ua/index.php/umj/article/view/1127
• Journal Title: Ukrains’kyi Matematychnyi Zhurnal

Under the conditions that a continuous $2\pi$-periodic function $f$ on the real axis changes its sign at $2s$ points $y_i\colon {-\pi}\le y_{2s}<y_{2s-1}<\ldots <y_1<\pi,$ $s\in\Bbb N,$ the other points $y_i,$ $i\in\Bbb Z,$ are defined by periodicity, and...