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JOURNALS // Matematicheskie Zametki // Archive

Mat. Zametki, 1973 Volume 13, Issue 5, Pages 637–646 (Mi mzm7167)

Diameters of certain sets in function spaces

Yu. I. Grigoryan

Erevan Polytechnic Institute

Abstract: The precise values of the diameters (according to A. N. Kolmogorov) of the class $H_C^\omega$ in the space $C[a,b]$ and lower bounds for the diameters of the class $H_p^\omega$ in the spaces $\widetilde {L_p}(o,2\pi)$ ($1\le p\le\infty$), for any modulus of continuity $\omega(\delta)$, are obtained. The latter bounds give the exact values of the odd-numbered diameters of the class $H_2^{1/2}=H_2^{\delta^{1/2}}$ and the exact order of decay of the diameters of the class $H_1^\omega$.

UDC: 517.5

Received: 10.11.1971


 English version:
Mathematical Notes, 1973, 13:5, 383–388

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© Steklov Math. Inst. of RAS, 2026