Abstract
The paper studies approximation and structural geometric-topological properties of sets in normed and more general (asymmetric) spaces for which there exists a continuous selection for the best and near-best approximation operators. Sufficient conditions on the metric projection of sets which ensure the existence of a continuous selection for this projection are obtained, and the structural properties of such sets are determined. The existence of a continuous selection for the near-best approximation operator on a finite-dimensional space more general than a normed space is investigated. It is shown that the lower semicontinuity of the metric projection is sufficient for the existence of a continuous selection for the near-best approximation operator in the general case.
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Original Russian Text © I.G. Tsar’kov, 2017, published in Doklady Akademii Nauk, 2017, Vol. 475, No. 4, pp. 373–376.
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Tsar’kov, I.G. Continuous selection from the sets of best and near-best approximation. Dokl. Math. 96, 362–364 (2017). https://doi.org/10.1134/S1064562417040196
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DOI: https://doi.org/10.1134/S1064562417040196