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JOURNALS // Ufimskii Matematicheskii Zhurnal // Archive

Ufimsk. Mat. Zh., 2024 Volume 16, Issue 2, Pages 3–15 (Mi ufa689)

On embedding into Lorentz spaces (a distant case)

A. T. Baidaulet, K. M. Suleimenov

L.N. Gumilyov Eurasian National University, Kazhymukan str. 13, 010000, Astana, Kazakhstan

Abstract: In the work we study an upper bound for a non–increasing non–negative function in the space $L^{p}(0,1)$ by the modulus of continuity of a variable increment $\omega_{p,\alpha,\psi}(f,\delta)$. We show that for the increment of the function of form $f(x)-f(x+hx^{\alpha}\psi(x))$ in the bound the modulus of continuity casts into the form $\omega_{p,\alpha,\psi}\left(f,\frac{\delta}{\delta^{\alpha}\psi\left(\frac{1}{\delta}\right)}\right)$. We also study the embedding $\tilde H_{p,\alpha,\psi}^\omega \subset L(\mu,\nu)(\mu \not= \nu)$ (a distant case). We obtained necessary and sufficient conditions for the parameters $p$, $\alpha$, $\mu$, $\nu$ and the functions $\psi$, $\omega$ for this embedding.

Keywords: classes of functions, modulus of continuity of variable increment, non–increasing permutation of the function, Lorentz spaces.

UDC: 517.958

MSC: 34B45, 81Q15

Received: 29.04.2023


 English version:
Ufa Mathematical Journal, 2024, 16:2, 1–14


© Steklov Math. Inst. of RAS, 2024