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- [This article was reproduced from a GNU Bulletin.]
-
- GNU Chess
- by Stuart Cracraft
- copyright 1987 Stuart Cracraft
-
-
- GNU Chess is a communal chess program. Contributors donate their
- time and effort in order to make it a stronger, better, sleeker program.
- Contributions take many forms: interfaces to high-resolution displays,
- opening book treatises, speedups of the underlying algorithms, additions
- of extra heuristics. These contributions are then distributed to the
- large user-base so that all may enjoy the fruits of our labor. The
- original and continuing purpose of this project is to permanently end
- the rampant hoarding of computer chess software that has been the
- case for the past 20 years.
-
- Many people have contributed to GNU Chess. Their contributions have
- improved the program from being a patzer (weak program) to being a
- grandpatzer (decently strong program). In its growth since initial
- release, GNU Chess has gone from approximately class D to expert
- strength. It beats the Fidelity Excel commercial unit rather handily.
-
- GNU Chess's structure is a hybrid of the Shannon Type-A and
- Type-B methods. It conducts a full-width search to a fixed-depth
- and then continues with a quiescence search for many more ply.
- This quiescence search helps the program find positions which
- can be safely evaluated and which are not too turbulent. If
- a terminal position is too turbulent, the evaluation will be
- highly inaccurate. Additional searching by investigating series
- of captures, checks, and other potentially imbalance-producing
- moves is quite helpful.
-
- GNU Chess will sacrifice pieces in order to reach known winning
- endings. Also, it uses a trade-down bonus to encourage the stronger
- side to trade off certain types of pieces thus reaching a more
- simplified and therefore ostensibly "clearer" position.
-
- GNU Chess has certain types of knowledge regarding easier endgames.
- This allows it to play these endings somewhat better than might be
- expected.
-
- GNU Chess has time heuristics that it uses to improve its handling
- of time-controls and hasten its making of "obvious" moves.
-
- GNU Chess is interfaced to the SUN Windows and X Windows
- display protocols and can display its pieces in elaborate format,
- similar to chess diagrams.
-
- GNU Chess has an opening book which consists of many variations
- from MCO (Modern Chess Openings).
-
- For comparison purposes, GNU Chess running on a VAX 8650 is
- stronger than the famous Chess 4.5 running on a CDC 6400.
-
- We wish to acknowledge the contributions of the following
- individuals: (in alphabetical order) Jim Aspnes, Wayne Christopher,
- Steve Dougherty, David Goldberg, Richard Greenblatt, David Kittinger,
- Richard Stallman, John Stanback, and Ken Thompson.
-
- Contact information: The author may be reached by a variety of
- methods. Via U.S. mail: Stuart Cracraft, 5 Via Amistosa, Suite G,
- Rancho Santa Margarita, Ca. 92688 USA.
- By Arpanet: 'cracraft@venera.isi.edu'.
- By uucp mail: 'ucbvax!venera.isi.edu!cracraft'.
- The author may also be contacted via the Free Software Foundation, Inc.
- 675 Massachusetts Ave.,Cambridge MA 02139.
-