The series presents lecture notes for advanced undergraduate courses taught by the American Mathematical Society and the Mathematics Advanced Study Semesters (MASS) program. Katok gave her MASS course in the fall of 2000; the notes were published in MASS Selecta and in a Russian version, but she has revised and expanded them for this volume. The many exercises are included, along with the homework assignments. Annotation ©2007 Book News, Inc., Portland, OR (booknews.com)