Acknowledgements. Some material in this book was presented in mini-courses
taught by JSC at the Instituto de Ciencias Matematica Sao Carlos, Universidade
de Sao Paulo, and Instituto de Matematica e Estatistica, Universidade de Sao
Paulo during 1996. His visit to Brasil was supported by a Faculty Service and
Development Award from the University of South Alabama, and by grants from
FAPESP, Brasil. Additional support for JSC was provided by a grant from the
National Security Agency. The University of South Florida supported MS with a
grant from the Research and Creative Scholarship Grant Program.
We offer our gratitude to several people for valuable discussions and comments.
First of all, we are grateful for our wives' and families' support and understanding
as the project was being developed. We have benefitted from correspondence and
comments of John Baez, Vera Carrara, Richard Hitt, Seiichi Kamada, Misha Kapra-
nov, Louis Kauffman, Laurel Langford, Joachim Rieger, Maria "Cindinha" Ruas,
Daniel Silver, James Stasheff, and Oleg Viro. The financial and moral support of
Cameron Gordon and Kunio Murasugi was essential during the early development
of this research. Sergei Gelfand and Sarah Donnelly at the AMS deserve special
kudos for working with us. They have been patient with our writing quirks, and
persistent in getting the manuscript to press.
J. Scott Carter