In this talk we consider a new class of convex optimization problems,
which admit faster black-box optimization schemes. For analyzing
their rate of convergence, we introduce a notion of mixed accuracy of an
approximate solution, which is a convenient generalization of
the absolute and relative accuracies. We show that for our problem
class, a natural Quasi-Newton method is always faster than the standard
gradient method. At the same time, after an appropriate normalization,
our results can be extended onto the general convex unconstrained
minimization problems.