Classical Inhomogeneities in String Cosmology

We generalize previous work on inhomogeneous pre-big bang cosmology by including the effect of nontrivial moduli and antisymmetric-tensor‐axion fields. The general quasihomogeneous asymptotic solution—as one approaches the big bang singularity from perturbative initial data—is given and its range of validity is discussed, allowing us to give a general quantitative estimate of the amount of inflation obtained during the perturbative pre-big bang era. The question of determining early-time ‘‘attractors’’ for generic pre-big bang cosmologies is also addressed, and a motivated conjecture is advanced. We also discuss S-duality-related features of the solutions, and speculate on the way an asymptotic T-duality symmetry may act on moduli space as one approaches the big bang. @S0556-2821~98!01104-7#