Singular Semi-Riemannian Geometry

This volume is an exposition of singular semi-Riemannian geometry: the study of a smooth manifold furnished with a degenerate (singular) metric tensor of arbitrary signature. The main topic of interest is those cases where metric tensors are assumed to be nondegenerate. In the literature manifolds with degenerate metric tensors have been studied extrinsically as degenerate submanifolds of semi-Riemannian manifolds. Here, the intrinsic structure of a manifold with a degenerate metric tensor is studied first, and then it is studied extrinsically by considering it as a degenerate submanifold of a semi-Riemannian manifold. The book is divided into three parts. The four chapters of Part I deal with singular semi-Riemannian manifolds. Part II is concerned with singular Kahler manifolds in four chapters parallel to Part I. Finally, Part III consists of three chapters treating singular quaternionic Kahler manifolds. This book is intended for graduate students of differential geometry, who have some background knowledge on the subject of complex manifolds already.