This is GNU Go 3.8, a Go program. Development versions of GNU Go may be found at http://www.gnu.org/software/gnugo/devel.html. Contact us at gnugo@gnu.org if you are interested in helping.

About GNU Go and this Manual
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The challenge of Computer Go is not to beat the computer, but to program the computer.

In Computer Chess, strong programs are capable of playing at the highest level, even challenging such a player as Garry Kasparov. No Go program exists that plays at the same level as the strongest human players.

To be sure, existing Go programs are strong enough to be interesting as opponents, and the hope exists that some day soon a truly strong program can be written. This is especially true in view of the successes of Monte Carlo methods, and a general recent improvement of computer Go.

Before GNU Go, Go programs have always been distributed as binaries only. The algorithms in these proprietary programs are secret. No-one but the programmer can examine them to admire or criticise. As a consequence, anyone who wished to work on a Go program usually had to start from scratch. This may be one reason that Go programs have not reached a higher level of play.

Unlike most Go programs, GNU Go is Free Software. Its algorithms and source code are open and documented. They are free for any one to inspect or enhance. We hope this freedom will give GNU Go's descendents a certain competetive advantage.

Here is GNU Go's Manual. There are doubtless inaccuracies. The ultimate documentation is in the commented source code itself.

The first three chapters of this manual are for the general user. Chapter 3 is the User's Guide. The rest of the book is for programmers, or persons curious about how GNU Go works.  Chapter 4 is a general overview of the engine.  Chapter 5 introduces various tools for looking into the GNU Go engine and finding out why it makes a certain move, and Chapters 6--7 form a general programmer's reference to the GNU Go API. The remaining chapters are more detailed explorations of different aspects of GNU Go's internals.

Copyrights
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Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 and 2008 by the Free Software Foundation except as noted below.

All source files are distributed under the GNU General Public License (see GPL, version 3 or any later version), except gmp.c, gmp.h, gtp.c, and gtp.h.

The files gtp.c and gtp.h are copyright the Free Software Foundation. In the interests of promoting the Go Text Protocol these two files are licensed under a less restrictive license than the GPL and are free for unrestricted use (see GTP License).

The two files gmp.c and gmp.h were placed in the public domain by William Shubert, their author, and are free for unrestricted use.

Documentation files (including this manual) are distributed under the GNU Free Documentation License (see GFDL, version 1.3 or any later version).

The files regression/games/golois/*sgf are copyright Tristan Cazenave and are included with his permission.

The SGF files in regression/games/handtalk/ are copyright Jessie Annala and are used with permission.

The SGF files in regression/games/mertin13x13/ are copyright Stefan Mertin and are used with permission.

The remaining SGF files are either copyright by the FSF or are in the public domain.

Authors
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GNU Go maintainers are Daniel Bump, Gunnar Farneback and Arend Bayer. GNU Go authors (in chronological order of contribution) are Man Li, Wayne Iba, Daniel Bump, David Denholm, Gunnar Farnebäck, Nils Lohner, Jerome Dumonteil, Tommy Thorn, Nicklas Ekstrand, Inge Wallin, Thomas Traber, Douglas Ridgway, Teun Burgers, Tanguy Urvoy, Thien-Thi Nguyen, Heikki Levanto, Mark Vytlacil, Adriaan van Kessel, Wolfgang Manner, Jens Yllman, Don Dailey, Måns Ullerstam, Arend Bayer, Trevor Morris, Evan Berggren Daniel, Fernando Portela, Paul Pogonyshev, S.P. Lee and Stephane Nicolet, Martin Holters, Grzegorz Leszczynski and Lee Fisher.

Thanks
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We would like to thank Arthur Britto, David Doshay, Tim Hunt, Matthias Krings, Piotr Lakomy, Paul Leonard, Jean-Louis Martineau, Andreas Roever and Pierce Wetter for helpful correspondence.

Thanks to everyone who stepped on a bug (and sent us a report)!

Thanks to Gary Boos, Peter Gucwa, Martijn van der Kooij, Michael Margolis, Trevor Morris, Måns Ullerstam, Don Wagner and Yin Zheng for help with Visual C++.

Thanks to Alan Crossman, Stephan Somogyi, Pierce Wetter and Mathias Wagner for help with Macintosh. And thanks to Marco Scheurer and Shigeru Mabuchi for helping us find various problems.

Thanks to Jessie Annala for the Handtalk games.

Special thanks to Ebba Berggren for creating our logo, based on a design by Tanguy Urvoy and comments by Alan Crossman. The old GNU Go logo was adapted from Jamal Hannah's typing GNU: http://www.gnu.org/graphics/atypinggnu.html. Both logos can be found in doc/newlogo.* and doc/oldlogo.*.

We would like to thank Stuart Cracraft, Richard Stallman and Man Lung Li for their interest in making this program a part of GNU, William Shubert for writing CGoban and gmp.c, Rene Grothmann for Jago and Erik van Riper and his collaborators for NNGS.

Development
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You can help make GNU Go the best Go program.

This is a task-list for anyone who is interested in helping with GNU Go. If you want to work on such a project you should correspond with us until we reach a common vision of how the feature will work!

A note about copyright. The Free Software Foundation has the copyright to GNU Go. For this reason, before any code can be accepted as a part of the official release of GNU Go, the Free Software Foundation will want you to sign a copyright assignment.

Of course you could work on a forked version without signing such a disclaimer. You can also distribute such a forked version of the program so long as you also distribute the source code to your modifications under the GPL (see GPL). But if you want your changes to the program to be incorporated into the version we distribute we need you to assign the copyright.

Please contact the GNU Go maintainers, Daniel Bump (bump@sporadic.stanford.edu) and Gunnar Farnebäck (gunnar@lysator.liu.se), to get more information and the papers to sign.

Bug reports are very welcome, but if you can, send us bug FIXES as well as bug reports. If you see some bad behavior, figure out what causes it, and what to do about fixing it. And send us a patch! If you find an interesting bug and cannot tell us how to fix it, we would be happy to have you tell us about it anyway. Send us the sgf file (if possible) and attach other relevant information, such as the GNU Go version number. In cases of assertion failures and segmentation faults we probably want to know what operating system and compiler you were using, in order to determine if the problem is platform dependent.

If you want to work on GNU Go you should subscribe to the GNU Go development list. (http://lists.gnu.org/mailman/listinfo/gnugo-devel) Discussion of bugs and feedback from established developers about new projects or tuning the existing engine can be done on the list.