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