GNU Chess: Experiences Learned
with Communal Sharing
by Stuart Cracraft
(and contributors to the GNU Project)
Limited sharing has characterized the computer chess community
for the past two decades. Occasional research articles give hintsand suggestions for useful features, but rarely reveal the real
details of the critically important advances. We will here
describe an effort underway (titled "GNU Chess") to create a moreopen and friendly environment of sharing.GNU Chess is part of Project GNU, a large‐scale effort in which
the philosophical goals are far‐reaching. We will not go into any
great depth about these goals as they relate to the larger pro‐
ject, because these are described elsewhere [1]. However, we will
mention the basic issues and the changes we hope to encourage.The start of the GNU Chess project was a natural result of theexperiences gleaned in writing a chess program. While the authorwas at a progressive academic location [2], he was able to con‐
ceive the idea of a communal chess program only after much heart‐
ache. During the period of writing the initial version (which
has since undergone many improvements and whole revisions), it
became clear that the best features and most useful hints, the
very best of the heuristics, were hidden and difficult to find in
the literature.Sprinkled across many books, research papers, magazine articles,
accumulated in the community, during the past 25 years, there was
literally a void of true, empirical programs. Locating usable
programs was difficult. Many programs were the result of academicwork in "ivory towers", and hence were inaccessible to the common
man. Other programs were sequestered in research think‐tanks. Na‐
turally, developers of commercial programs carefully guarded
their source in order to protect their investment. On the otherhand, a few chess program source listings had actually been pub‐
lished, but these were not really very strong, often written in a
non‐general language, and frequently more pedantic than practi‐
cal.The idea of a reasonably strong communal program solidified.When we refer to a communal program, we do not regard this as
public‐domain software. Rather, we refer to a program which is
under the shared authority of a number of individuals, the prin‐
cipal contributors. These individuals have experienced and real‐
ized the positive results of a sharing community and the rapidimprovements that come through contributing in such a community.Further, these individuals devote time and energy to coordinating
the contributions of other individuals. While they exercise a
certain editorial right, this is usually not exercised arbitrari‐
ly; instead, a discussion is often undertaken.
Eventually, a working C program that played chess was available.
The coordinating institution for Project GNU [3], accepted our
suggestion of inclusion of a chess program in the GNU distribu‐
tion. Initial distribution of GNU Chess commenced in October of
1986. Interest in the project increased rapidly.Contributions came in from many places and people. Interfaces toX‐windows and SUN‐windows were donated, thus allowing very fancy
chess fonts on bit‐mapped screens. Also, contributions involving
large portions of opening books such as MCO and collections of
master games were added to the distribution. Additionally,
tree‐search modifications and heuristics were provided, and occa‐
sionally even entire rewrites.The program advanced in strength by several USCF class intervals
during a period of less than one year. During this time, many
unusual features and enhancements were added to the program, usu‐
ally under the coordination of two or more people, with one work‐
ing in a distant‐advisory capacity to the other. Frequently, gra‐
duate students would give up significant time from their thesis
work to devote energy to contributing. Their corporate counter‐
parts would often give up project time to make their donation.Contributors would often enter the project in a very forceful wayand then having made their contribution, learn the viability of
communal sharing once others had stepped in and contributed tothem, thus providing considerable reinforcement. Frequently, con‐
tributors would then go into "hibernation" for a long period oftime, but most of them remained open to contributing and were
helpful when asked to reprogram their particular contribution ina more recent version.GNU Chess has made great strides in relatively little time. Ithas run on many different hardware architectures and has beencompiled by a number of C compilers [4]. A sampling of the com‐
puters on which the program has run is: National 32032, Vax
11/750, 8550, 8600, 8650, Motorola 68020, CCI 5/32, CCI 6/32
(tahoe), Cray XMP.
It is our belief that GNU Chess will stimulate graduate research
in computer chess theory and practice. When students are able to
easily obtain a state‐of‐the‐art program in order to test out
their ideas, they will no longer need to reinvent the wheel. The
students will be able to investigate their research areas muchmore thoroughly, because they will spend more time on the specif‐
ic research areas they are concerned about. Basically, GNU Chess
"frees up" time in order to get on to more fundamental issues.
We also feel that as other researchers gain trust in the GNU
Chess project, they will be more likely to release their results
directly and rapidly, through journal articles, or directly to
the GNU project, and in fact become contributors and join the
present list [5]. At the very least, a communal, ever‐growing
program will encourage the few "closeted" researchers to be some‐
what more open in their approach to disseminating advances.In whatever form it takes, the progress toward elaboration of
machine chess is ongoing, and we hope that GNU chess will be
helpful to the community. Copies of GNU Chess source and "book",
as well as additional experimental code are available from theFree Software Foundation [3] or the author [6].
[1] The GNU Manifesto, Richard Stallman, Free Software Founda‐
tion, Inc.
[2] University of Southern California, Information Sciences In‐
stitute.
