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Entropy and approximation numbers of limiting embeddings; an approach via Hardy inequalities and quadratic forms. (English) Zbl 1242.47018
Let $B$ be the unit ball in ${ℝ}^{n}$. The paper deals with the continuous embeddings of a special weighted Sobolev space of functions defined on $B$ into the Lebesgue space of complex-valued measurable functions on $B$. The weights involve log-terms. In the case where the embeddings are compact, some two-sided estimates for the entropy numbers and approximation numbers are proved.
##### MSC:
 47B06 Riesz operators; eigenvalue distributions; approximation numbers, $s$-numbers etc.of operators 41A46 Approximation by arbitrary nonlinear expressions; widths and entropy 47B38 Operators on function spaces (general)
##### References:
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