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BRIEF MESSAGE
Approximation by spherical polynomials in $L^{p}$ for $p<1$
D. V. Gorbacheva, N. N. Dobrovolskiiba a Tula State University (Tula)
b Tula State Lev Tolstoy Pedagogical University (Tula)
Abstract:
Based on recently proved estimates for the $L^{1}$-Nikolskii constants for $\mathbb{S}^{d}$ and $\mathbb{R}^{d}$, effective bounds for the constant $K$ are given in the following inequality of the type Brown–Lucier for functions $f\in L^{p}(\mathbb{S}^{d})$, $0<p<1$:
$$
\|f-E_{1}f\|_{p}\le (1+2K)^{1/p}\inf_{u\in \Pi_{n}^{d}}\|f-u\|_{p},
$$
where $\Pi_{n}^{d}$ is the subspace of spherical polynomials, $E_{1}f$ is a best approximant of $f$ from $\Pi_{n}^{d}$ in the metric $L^{1}(\mathbb{S}^{d})$. The results are generalized to the case of the Dunkl weight.
Keywords:
spherical polynomial, best approximant, Nikoskii constant, Dunkl weight.
Received: 10.06.2021 Accepted: 20.09.2021
Citation:
D. V. Gorbachev, N. N. Dobrovolskii, “Approximation by spherical polynomials in $L^{p}$ for $p<1$”, Chebyshevskii Sb., 22:3 (2021), 453–456
Linking options:
https://www.mathnet.ru/eng/cheb1086 https://www.mathnet.ru/eng/cheb/v22/i3/p453
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Abstract page: | 131 | Full-text PDF : | 41 | References: | 15 |
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