Abstract
Techniques are developed to obtain strong converse inequalities for various linear approximation processes. This will establish equivalence between the approximating rate of a certain linear process and the appropriate PeetreK-functional. Approximation processes that will be treated have to be saturated asK-functionals are saturated. These general methods will lead to new results on the various trigonometric polynomial approximation processes, on holomorphic semigroups, on Bernstein polynomials and on other commonly used approximation processes.
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Supported by NSERC A4816 of Canada.
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Ditzian, Z., Ivanov, K.G. Strong converse inequalities. J. Anal. Math. 61, 61–111 (1993). https://doi.org/10.1007/BF02788839
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DOI: https://doi.org/10.1007/BF02788839