Boyanov–Naydenov problem and the inequalities of various metrics

• Date: 2026
• Main Authors: Doroshenko, D., Kofanov, V., Дорошенко, Данііл, Кофанов, Володимир, Кофанов, Владимир Александрович
• Format: Article
• Language: Ukrainian
• Published: Institute of Mathematics, NAS of Ukraine 2026
• Online Access: https://umj.imath.kiev.ua/index.php/umj/article/view/9328
• Journal Title: Ukrains’kyi Matematychnyi Zhurnal

UDC 517.51 We solve the Boyanov–Naidenov problem $\|x\|_{q, \delta} \to \sup$ on classes of differentiable functions $ W^r_{p, \omega}(A_0, A_r) := \{x\in L^r_{\infty}\colon \|x\|_{p, \omega} \le A_0,$ $ \|x^{(r)}\|_{\infty} \le A_r \}, $ where $\|x\|_{p, \, \delta} := \sup \{\|x\|_{L_p[a, b]}\colon...