The Meaning of Deep Blue's Victory.
May 26, 1997, Vol. 2, No. 36 • By CHARLES KRAUTHAMMER
"What we have is the world's best chess player vs. Garry Kasparov."
-- Louis Gerstner, CEO of IBM
When on May 11 Deep Blue, an IBM computer, defeated Garry Kasparov in the sixth and deciding game of their man-vs.-machine match, the world took notice. It made front pages everywhere. Great story: BOX DEFEATS WORLD CHESS CHAMPION. Indeed: BOX DEFEATS BEST PLAYER OF ALL TIME. Kasparov is so good that in his entire life he has never once lost a match -- and he has been involved in some of the epic matches in chess history, including several Ali- Frazier-like classics with former world champion Anatoly Karpov.
Deep Blue won 2-1, with 3 draws. Nonetheless, the real significance of the match lay not in the outcome, however stunning. Why? Because the match was tied until Game Six and Game Six was decided by a simple misplay of the opening. Kasparov played the wrong move order -- making what should have been move 9 on move 7 -- and simply could not recover.
It was a temporary lapse of memory. (Most openings have been tested so many times by trial and error that there is no need to figure them out during the game. You come in knowing them by heart.) Such lapses are fatal against Deep Blue, however. This brute contains in its memory every opening of every recorded game played by every grandmaster ever. Deep Blue's "opening book" spotted the transposition immediately and pounced. Twelve moves later, his position in ruins, Kasparov resigned.
Blunders of this sort are entertaining and sensational. But they are not very illuminating. The real illumination in this match -- the lightning flash that shows us the terrors to come -- came in Game Two, a game the likes of which had never been seen before.
What was new about Game Two -- so new and so terrifying that Kasparov subsequently altered his style, went on the defensive, and eventually suffered a self-confessed psychological collapse ("I lost my fighting spirit") -- was that the machine played like a human. Grandmaster observers said that had they not known who was playing they would have imagined that Kasparov was playing one of the great human players, maybe even himself. Machines are not supposed to play this way.
What did Deep Blue do? What does it mean to play like a human?
We must start by looking at what it means to play like a computer. When computers play chess, or for that matter when they do anything, they do not reason. They do not think. They simply calculate.
In chess, it goes something like this. In any given position, the machine calculates:
"If I do A, and he does B, and I then do C, and he does D . . . then I will end up with position X."
"On the other hand, if I do A and he does B and I do C and he does not D but E . . . I'll end up with position Y."
Deep Blue, the most prodigious calculator in the history of man or machine, can perform this logic operation 200 million times every second. This means that in the average of three minutes allocated for examining a position, it is actually weighing 36 billion different outcomes.
Each outcome is a new position -- how the board will look -- -a few moves down the road (in our example: X and Y). The machine then totes up the pluses and minuses of each final position (for instance, a lost queen is a big minus, bishops stuck behind their own pawns are a smaller minus), chooses the one in 36 billion that has the highest number, and makes the move.
This is called "brute force" calculation and it is how Deep Blue and all good computers work. This is not artificial intelligence, which was the alternative approach to making computers play chess and do other intellectual tasks. In artificial intelligence you try to get the machine to emulate human thinking. You try to teach it discrimination, pattern recognition, and the like. Unfortunately, artificial-intelligence machines turn out to be a bust at chess.
The successful machines simply calculate. And it is with this kind of calculating ability that Deep Blue beat Kasparov last year in Game One of their maiden match in Philadelphia. It was the first time a computer had ever won a game from a world champion and it caused a sensation.
It happened this way: Late in the game Deep Blue found its king under fierce attack by Kasparov. Yet Deep Blue momentarily ignored the threat (lose the king and you lose the game) and blithely expended two moves going after a lowly stray (Kasparov) pawn. The experts were aghast. No human player would have dared do this. When your king is exposed, to give Kasparov two extra moves in which to press his attack is an invitation to suicide.