Rodríguez, José M.; Yakubovich, Dmitry V. A Kolmogorov-Szegö-Krein type condition for weighted Sobolev spaces. (English) Zbl 1074.41004 Indiana Univ. Math. J. 54, No. 2, 575-598 (2005). An analogue of the Szegő condition for density of analytic polynomials in a weighted Sobolev space \( W^{k,p}\) of the circle with general weights is given here. This work of the authors is particularly close to questions studied in [J. A. Ball and T. R. Fanney, J. Oper. Theory 33, 43–78 (1995; Zbl 0849.47011)]. It is also observed that the solution of the question of density of analytic polynomials in weighted Sobolev spaces is of importance in the theory of sub-Jordan operators. Reviewer: H. P. Dikshit (New Delhi) Cited in 5 Documents MSC: 41A10 Approximation by polynomials Keywords:Szegö condition; weight; Sobolev spaces; weighted Sobolev spaces Citations:Zbl 0849.47011 PDFBibTeX XMLCite \textit{J. M. Rodríguez} and \textit{D. V. Yakubovich}, Indiana Univ. Math. J. 54, No. 2, 575--598 (2005; Zbl 1074.41004) Full Text: DOI