The texts published in this series are intended for graduate students and all mathematicians who wish to broaden their research horizons or who simply want to get a better idea of what is going on in a given field. They are introductions to areas that are close to modern research and prepare the reader for a better understanding of research papers. Many of the books can also be used to supplement graduate course programs. Editor for Vieweg's Aspects of Mathematics series is Klas Diedrich. The AMS is exclusive distributor in North America. Vieweg Verlag Publications are available worldwide from the AMS outside of Germany, Switzerland, Austria, and Japan. (ISSN 0179-2156). Hardcover.