Babaev, M. B. A. Approximation of Sobolev classes of functions by sums of products of functions of a lesser number of variables and quasidiameters. (Russian. English summary) Zbl 0604.41030 Dokl., Akad. Nauk Az. SSR 42, No. 3, 3-5 (1986). This article is devoted to the approximation of the Sobolev class of functions by some variety representing the sum of products of functions of lesser number of variables. Two further types of quasi-widths are introduced and estimated: Kolmogorov and Alexandrov ones. Cited in 3 Documents MSC: 41A46 Approximation by arbitrary nonlinear expressions; widths and entropy 41A65 Abstract approximation theory (approximation in normed linear spaces and other abstract spaces) Keywords:Kolmogorov quasi-widths; Alexandrov quasi-widths; Sobolev class of functions PDFBibTeX XMLCite \textit{M. B. A. Babaev}, Dokl., Akad. Nauk Az. SSR 42, No. 3, 3--5 (1986; Zbl 0604.41030)