Abstract (Elsevier)
A manifestly world sheet supersymmetric description of nontoroidal compactification is given. Supersymmetric chirally bosonized actions are shown to play an important role. We also construct nonlinear σ -models which allow the effective action for four-dimensional compactified string theories to be computed via the “ β -function” method. The specific model for the SO(44) four-dimensional heterotic string is explicitly given.