DOI: 10.33205/cma.1886631 ISSN: 2651-2939

Quantitative estimates and near-best properties of extended best approximation in $\Gamma_{w,q}$ spaces for \(0 < q \le 1\)

Maria Ines Gareis, Federico Dario Kovac, Fabian Eduardo Levis, Ludmila Zabala
This article investigates the extended best polynomial approximation operator, defined on the space of measurable functions, within the setting of Lorentz Gamma spaces \(\Gamma_{ w,q}\) for \(0 &lt; q \le 1\). We derive quantitative estimates for extended best approximations and the outer operator quasi-norm. As a consequence, we show that extended best approximations in \(\Gamma_{ w,1}\) are near-best approximations in \(\Gamma_{ w,q}\).

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