Geometry and Quantum Symmetries of Superstring Vacua

Abstract

We report on some recent progress which has been made in the understanding of general features of superstring compacti cations. The following aspects are discussed: special geometry of the moduli space of (2,2) vacua, target-space duality symmetries, di erential equations for the periods of holomorphic three-forms, and higher loop (genus) string corrections to the tree-level e ective action through target-space modular anomaly cancellations.