Deformation theory of singular symplectic n-folds

Abstract

The notion of a holomorphically symplectic manifold can be generalized to the singular one. This paper studies the birational contraction maps between symplectic varieties, and then describes the deformation of a symplectic variety which has a symplectic resolution. Some examples are also included.

28 pages, to appear in Math. Ann The proof of (2.6) became short. Appendix is added