Moduli spaces and locally symmetric varieties

Abstract

This survey paper is about moduli spaces in algebraic geometry for which a period map gives that space the structure of a (possibly incomplete) locally symmetric variety and about their natural compactifications. We outline the Baily-Borel compactification for such varieties, and show that it usually differs from the compactifications furnished by the standard techniques in algebraic geometry. It turns out however, that a reconciliation is possible by means of a generalization of the Baily-Borel construction for the class of incomplete locally symmetric varieties that occur here.

The emphasis is here on moduli spaces of varieties other than that of polarized abelian varieties.