Abstract:
We obtain upper and lower bounds for the best accuracy of approximation in
Stechkin's problem for the differentiation operator and in the problem of the
reconstruction of the derivative from the values of the function at a given
number of points for Nikol'skii and Besov classes of functions satisfying
mixed Hölder's conditions. These estimates give the order of these
quantities for almost all values of the parameters involved.
Keywords:accuracy, approximation, differential operator, recovery, derivative, function values, mixed.