  For a class of Friedmann-Robertson-Walker type string solutions with compact
hyperbolic spatial slices formulated in critical dimension, we find the world
sheet conformal field theory which involves the linear dilaton and
Wess-Zumino-Witten type model with the compact hyperbolic target space. By
analyzing the infrared spectrum, we conclude that the theory is actually
supercritical due to the modular invariance of string theory. Thus, taking into
account previous results, we conclude that all the simple nontrivial string
cosmological solutions are supercritical. A possible explanation of why we are
living in D=4 is provided. The interesting relation of this background with the
Supercritical String Cosmology (SSC) is pointed out.
