I have no intent to publish this book with a traditional publisher, so
it will remain freely available indefinitely. If you have comments,
corrections, suggestions for additions, etc., please send them to me!

--------------

Copyright: William Stein, 2004.

License: FREE! More precisely,
this book my be freely redistributed, copied, or even sold without
requiring you to obtain written permission from me. You may even
extend or change this book, but this preface page must remain in any
derived work, and any derived work must also remain free, including
the L^{A}TEX source files. In particular, I have no interest in
making any money from this book.

Please send me any typos or corrections: ` [email protected]`.

**Acknowledgement:** This book closely builds on
Swinnerton-Dyer's book [SD01] and Cassels's article
[Cas67]. Many of the students of Math 129 at Harvard
during Spring 2004 made helpful comments: Jennifer Balakrishnan, Peter
Behrooz, Jonathan Bloom, David Escott Jayce Getz, Michael Hamburg,
Deniz Kural, Danielle li, Andrew Ostergaard Gregory Price, Grant
Schoenebeck, Jennifer Sinnott, Stephen Walker, Daniel Weissman, and
Inna Zakharevich. Also the course assistant Matt Bainbridge made many
helpful comments.

William Stein 2004-05-06