Behavior of the entropy numbers of classes of multivariate functions with
mixed smoothness is studied here. This problem has a long history and some
fundamental problems in the area are still open. The main goal of this paper is
to develop a new method of proving the upper bounds for the entropy numbers.
This method is based on recent developments of nonlinear approximation, in
particular, on greedy approximation. This method consists of the following two
steps strategy. At the first step we obtain bounds of the best m-term
approximations with respect to a dictionary. At the second step we use general
inequalities relating the entropy numbers to the best m-term approximations.
For the lower bounds we use the volume estimates method, which is a well known
powerful method for proving the lower bounds for the entropy numbers. It was
used in a number of previous papers.