Singularities of solutions of differential equations forms the common
theme of these papers taken from a seminar held at the Institute for
Advanced Study in Princeton in 1977-1978. While some of the lectures
were devoted to the analysis of singularities, others focused on
applications in spectral theory. As an introduction to the subject, this
volume treats current research in the field in such a way that it can be
studied with profit by the non-specialist.