  The evolution of sub-spaces in the framework of gravity with higher
derivatives is studied. Numerical solutions to exact differential equations are
found. It is shown that the initial conditions play crucial role in the space
dynamic. Appropriate metrics describing an expanding and a stationary sub-space
shed light on the well-known question: why our 3-dim space is large but extra
space is small and stable (if exists)? It is assumed that the values of
parameters at high energies strongly depend on uncontrolled quantum corrections
and, hence, are not equal to their values at low energies. Therefore, there is
no way to trace solutions throughout the energy range, and we restrict
ourselves to the sub-Planckian and the inflationary energies.
