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preface.dvi
Games of No Chance
MSRI Publications
Volume 29 , 1996
Preface
Combinatorial Game Theory, as an academic discipline, is still in its infancy.
Many analyses of individual games have appeared in print, starting in 1902 with
C. L. Bouton's analysis of the game of Nim. (For exact references to the works
mentioned here, please see A. Fraenkel's bibliography on pages 493{537 of this
volume.) It is was not until the 1930's that a consistent theory for impartial
games was developed, independently, by R. Sprague and P. M. Grundy, later to
be expanded and expounded upon by R. K. Guy and C. A. B. Smith. (Guy is
still going strong, as evidenced by his energy at this Workshop.) J. H. Conway
then developed the theory of partizan games, which represented a major advance.
Based on this theory, D. Knuth wrote his modern moral tale, Surreal Numbers .
The collaboration of E. R. Berlekamp, J. H. Conway and R. K. Guy gave us
Winning Ways , which \set to music", or at least to \rhyme", the theory so far.
In the process, many more games were discovered and analyzed: but more were
discovered than solved!
This Workshop, held from 11 to 21 July 1994, gave evidence of the growing
interest in combinatorial games on the part of experts from many elds: math-
ematicians, computer scientists, researchers in articial intelligence, economists,
and other social scientists. Players, some of whom make their living from games,
also attended. Visitors such as D. Knuth and H. Wilf dropped in for a few
hours or days and gave impromptu lectures. There was much cross-fertilization
of ideas, as could be expected from a meeting of people from such varied back-
grounds. One major paper by A. Fraenkel (pages 417{431) was conceived and
essentially written during the Workshop, being inspired by V. Pless's talk.
But the Workshop was not all seminars. There were books, games and puz-
zles on display. Two ocial tournaments, Dots-and-Boxes and Domineering,
attracted a lot of participants, and carried $500 rst prizes (funded by E. R. B.)
The nal matches were shown over closed-circuit TV, so that the spectators
could have a running commentary! (See pages 79{89.) Neither game is com-
pletely solved: Dots-and-Boxes is played by many school children, yet still holds
mysteries for adults.
The articles in this volume are divided into four groups. Part I is introductory.
Part II contains papers on some of the \classical" games, such as chess and
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PREFACE
Go. Part III studies many other games, of greatly varying degrees of diculty.
Part IV contains articles that push the traditional theory in new directions:
for example, by considering games more general than the strict denition of
combinatorial games allows (see pages 1 and 363). The book closes with a list
of unsolved problems by R. K. Guy, and a Master Bibliography by A. Fraenkel.
The increasing role of computers can be witnessed throughout, in areas ranging
from the solution of particular games to the use of the computer in teaching
humans.
Many thanks must go the sta of MSRI, who helped make the Workshop a
success. The facilities were wonderful. Thanks are due also to the Workshop
chairs, E. R. Berlekamp and R. K. Guy. Together with the rest of the orga-
nizing committee (J. H. Conway, N. D. Elkies, A. S. Fraenkel, J. G. Propp, K.
Thompson, and myself), they put together a wonderful and rich program.
In the preparation of this book, we are especially grateful to Silvio Levy,
who essentially rewrote two of the articles, edited all the others, found good
placements for the more than 200 gures, redrew some of them, and arranged
the typesetting.
Richard J. Nowakowski
All Games Bright and Beautiful
What is a combinatorial game? The usual denition is a game in which
(i) there are two players moving alternately;
(ii) there are no chance devices and both players have perfect information;
(iii) the rules are such that the game must eventually end; and
(iv) there are no draws, and the winner is determined by who moves last.
In this section, two master expositors lead us through many examples of such
games, and introduce the theory that has been developed to deal with them
(pages 13{78). As an appetizer, you may prefer to read rst J. H. Conway's
charming study (pages 3{12) of a game that does not satisfy this denition,
because it may well be endless. Or, if you already know the basic theory and
are dying for action, turn to the reports of the Workshop tournament nals, on
pages 79{89; or download the Gamesman's Toolkit, described on pages 93{98.
Have fun!
Strides on Classical Ground
The origins of chess and related games are lost in time; yet, in spite of hundreds of
years of analysis, they remain as interesting as ever, because of their fantastically
large conguration space. The articles presented here are steps in the continuing
endeavor to master these games, an endeavor in which the computer nowadays is
often a valuable tool. In fact, the \simpler" board game Nine Men's Morris has
succumbed to computer analysis, as reported by R. Gasser. Checkers may well
be on its way: J. Schaeer tells of the development of the program Chinook, and
pays a tribute to the extraordinary (human!) player M. Tinsley. N. Elkies and
L. Stiller write articles about chess, computerless in one case and computer-heavy
in the other. Shogi, also called Japanese chess, is Y. Kawano's subject.
The last four articles of this section deal with Go, a game that has come
under intense scrutiny recently. Although it is a territorial game and not, strictly
speaking, a combinatorial game according to the denition on page 1, the board
breaks up toward the end into a sum of smaller independent games, a situation
that the theory of combinatorial games handles well. Other aspects of Go, such
as ko, require extensions of the traditional theory, as explained in two of these
articles.
Taming the Menagerie
This section collects seven analyses of \simple" games in their dizzying variety:
from the hitherto ignored sowing games (where counters are distributed from one
pile to others, without ever being removed from the game) to take-away games
(where there is only one pile, but the rule specifying how many counters can
be removed may be endishly complicated). Not surprisingly, complete analyses
are hard to come by, but several interesting general results are proved. There
is also a description of a computer interface for Domineering, that archetype of
partizan board games, amazing in its economy and elegance.
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