Copyright (C) Peter Wentworth, Jeffrey Elkner, Allen B. Downey and Chris Meyers.

Edited by Martin Roelfs, Peter Kroon, Kasper Loopstra, Jonathan Barnoud,

Manuel Nuno Melo and Lourens-Jan Ugen.

Permission is granted to copy, distribute and/or modify this document

under the terms of the GNU Free Documentation License, Version 1.3

or any later version published by the Free Software Foundation;

with Invariant Sections being Foreword, Preface, and Contributor List, no

Front-Cover Texts, and no Back-Cover Texts. A copy of the license is

included in the section entitled "GNU Free Documentation License".