Vakarchuk, S. B.; Zabutnaya, V. I. Inequalities between best polynomial approximations and some smoothness characteristics in the space \(L_2\) and widths of classes of functions. (English. Russian original) Zbl 1342.41033 Math. Notes 99, No. 2, 222-242 (2016); translation from Mat. Zametki 99, No. 2, 215-238 (2016). MSC: 41A50 41A17 PDFBibTeX XMLCite \textit{S. B. Vakarchuk} and \textit{V. I. Zabutnaya}, Math. Notes 99, No. 2, 222--242 (2016; Zbl 1342.41033); translation from Mat. Zametki 99, No. 2, 215--238 (2016) Full Text: DOI
Vakarchuk, Sergei B.; Shabozov, Mirgand Sh.; Zabutnaya, Valentina I. Structural characteristics of functions from \(L_2\) and the exact values of widths of some functional classes. (English. Ukrainian original) Zbl 1323.41015 J. Math. Sci., New York 206, No. 1, 97-114 (2015); translation from Ukr. Mat. Visn. 11, No. 3, 417-441 (2014). MSC: 41A17 41A50 41A10 PDFBibTeX XMLCite \textit{S. B. Vakarchuk} et al., J. Math. Sci., New York 206, No. 1, 97--114 (2015; Zbl 1323.41015); translation from Ukr. Mat. Visn. 11, No. 3, 417--441 (2014) Full Text: DOI
Vakarchuk, S. B.; Zabutnaya, V. I. A sharp inequality of Jackson-Stechkin type in \(L_{2}\) and the widths of functional classes. (English. Russian original) Zbl 1194.42005 Math. Notes 86, No. 3, 306-313 (2009); translation from Mat. Zametki 86, No. 3, 328-336 (2009). MSC: 42A10 41A17 41A46 PDFBibTeX XMLCite \textit{S. B. Vakarchuk} and \textit{V. I. Zabutnaya}, Math. Notes 86, No. 3, 306--313 (2009; Zbl 1194.42005); translation from Mat. Zametki 86, No. 3, 328--336 (2009) Full Text: DOI
Vakarchuk, S. V.; Zabutnaya, V. I. On Jackson type inequalities and width of classes of periodical functions in the space \(L_2\). (Russian) Zbl 1199.41068 Zb. Pr. Inst. Mat. NAN Ukr. 5, No. 1, 37-48 (2008). MSC: 41A17 PDFBibTeX XMLCite \textit{S. V. Vakarchuk} and \textit{V. I. Zabutnaya}, Zb. Pr. Inst. Mat. NAN Ukr. 5, No. 1, 37--48 (2008; Zbl 1199.41068)