The Age of Spiritual Machines
- by
Raymond Kurzweil © 1990, MIT Press
Part V - "The World Chess
Championship"
Excerpts from his book:
PART v
"The
World Chess Championship"
As noted earlier, the best machine chess players are now competing
successfully at the national senior-master level, regularly defeating all but about 700
players. All chess machines use some variant of the recursive algorithm called
minimax, a
strategy whose computational requirements are multiplied by some constant for each
additional move ahead that is analyzed. Without a totally new approach, we thus need to
make exponential progress in computational power to make linear gains in game-playing
performance (though we are indeed making exponential progress in hardware). The analysis I
gave before estimated that the requisite computer power to achieve world-championship
chess playing should become available between 9 and 54 years from now. This estimate was
based on the continuing gains anticipated in the speeds of individual microprocessors. If
we factor in the increasing popularity of parallel-processing architectures, the result
will be much closer to the short end of this range. Some of the other scenarios in this
section require significant advances in both hardware power and software sophistication.
In my view, the ability of a machine to play championship chess is primarily a function of
the former. Some of the possible breakthroughs in electronic hardware discussed below will
be directly applicable to the chess issue. For example, if we are successful in harnessing
the third dimension in chip fabrication (that is, building integrated circuits with
hundreds or thousands of layers of active circuitry rather than just one), we will see a
major improvement in parallel processing: hundreds or thousands of processors on a single
chip. Taking into consideration only anticipated progress in conventional circuit-board
fabrication methodologies and continued development of parallel-processing architectures,
I feel that a computer world chess champion is a reasonable expectation by the end of the
century.
What will be the impact of such a development? For many, such as myself,
it will simply be the passing of a long anticipated milestone. Yes, chess is an
intelligent game (that is, it requires intelligence to play well), but it represents a
type of intelligence that is particularly well suited to the strengths of early machine
intelligence, what I earlier called level-2 intelligence (see "The Recursive Formula
and Three Levels of Intelligence"). While level-3 intelligence will certainly benefit
from the increasing power of computer hardware, it will also require substantial
improvements in the ability of computers to manipulate abstract concepts.
Defenders of human chess playing often say that though computers may
eventually defeat all human players, computers are not able to use the more abstract and
intuitive methods that humans use. For example, people can eliminate from consideration
certain pieces that obviously have no bearing on the current strategic situation and thus
do not need to consider sequences of moves involving those pieces. Humans are also able to
draw upon a wealth of experience of previous similar situations. However, neither of these
abilities is inconsistent with the recursive algorithm. The ability to eliminate from
consideration branches of the expanding tree of move-countermove possibilities not worth
pursuing is an important part, called pruning, of any minimax program. Drawing upon a data
base of previous board positions is also a common strategy in the more advanced chess
programs (particularly in the early game). It is estimated that human chess masters have
memorized between 20,000 and 50,000 chess boards. While impressive, it is clear that this
is again an area where machines have a distinct edge. There is little problem in a
computer mastering millions of board positions (each of which can have been analyzed in
great depth in advance). Moreover, it is feasible for computers to modify such previously
stored board positions to use them even if they do not precisely match a current position.
It may very well be that human players deploy methods of abstraction
other than recalling previous board positions, pruning and move expansion. There is little
evidence, however, that for the game of chess such heuristic strategies are inherently
superior to a simple recursive strategy combined with massive computational power. Chess,
in my view, is a good example of a type of intelligent problem solving well suited to the
strengths of the first half century of machine intelligence. For other types of problem
solving (level-3 problems), the situation is different.
Not everyone will cheerfully accept the advent of a computer chess
champion. Human chess champions have been widely regarded as cultural heroes, especially
in the Soviet Union; we regard the world chess championship as a high intellectual
achievement. If someone could compute spreadsheets in his head as quickly as (or faster
than) a computer, we would undoubtedly regard him as an amazing prodigy, but not as a
great intellect (in fact, he would actually be an idiot savant). A computer chess
championship is likely to cause a watershed change in how many observers view machine
intelligence (though perhaps for the wrong reasons). More constructively, it may also
cause a keener appreciation for the unique and different strengths (at least for the near
future) of machine and human intelligence.
