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On geometric properties of Morrey spaces. (English) Zbl 1474.46030

Ufim. Mat. Zh. 13, No. 1, 131-136 (2021) and Ufa Math. J. 13, No. 1, 131-136 (2021).
Summary: The study of Morrey spaces is motivated by many reasons. Initially, these spaces were introduced in order to understand the regularity of solutions to elliptic partial differential equations [F. Chiarenza and M. Frasca, Proc. Am. Math. Soc. 108, No. 2, 407–409 (1990; Zbl 0694.46029)]. In line with this, many authors study the boundedness of various integral operators on Morrey spaces. In this article, we are interested in their geometric properties, from functional analysis point of view. We show constructively that Morrey spaces are not uniformly non-\(\ell^1_n\) for any \(n\geqslant 2\). This result is sharper than earlier results, which showed that Morrey spaces are not uniformly non-square and also not uniformly non-octahedral. We also discuss the \(n\)-th James constant \(C_{\mathrm{J}}^{(n)}(X)\) and the \(n\)-th von Neumann-Jordan constant \(C_{\mathrm{NJ}}^{(n)}(X)\) for a Banach space \(X\), and obtain that both constants for any Morrey space \(\mathcal{M}^p_q(\mathbb{R}^d)\) with \(1\leqslant p<q<\infty\) are equal to \(n\).

MSC:

46B20 Geometry and structure of normed linear spaces
46E30 Spaces of measurable functions (\(L^p\)-spaces, Orlicz spaces, Köthe function spaces, Lorentz spaces, rearrangement invariant spaces, ideal spaces, etc.)
42B35 Function spaces arising in harmonic analysis

Citations:

Zbl 0694.46029

References:

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