Expositions of mathematical subjects set forth in a manner comprehensible not only to teachers and students specializing in mathematics, but also to scientific workers in other fields. The monographs are intended for the wide circle of thoughtful people familiar with basic graduate or advanced undergraduate mathematics, encountered in the study of mathematics itself, or in the context of related disciplines, who wish to extend their knowledge without prolonged and critical study of the mathematical journals and treatises. The books in this series are hardbound.