"It can't be bargained with. It can't be reasoned with. It doesn't feel pity, or remorse, or fear," said the hunted human, Reese, of the title character in the movie, The Terminator. He could have been speaking of Deep Junior (DJ), the computer chess champion of the world. After a six-game match slugged out over two weeks in New York City against Garry Kasparov, the highest-rated human player ever, the computer managed an even score.

Jeff Christensen/Reuters

Chess grandmaster Garry Kasparov studies the board in the fourth game of his match against Deep Junior, in New York City. The six-game contest ended in a draw on 7 February.

Matters could hardly have gone better for the event's chief sponsor, the International Chess Federation (FIDE, Lausanne), which put up a US $1 million prize. Upwards of two million people followed the games live on a number of Web sites that carried move-by-move commentary by grandmasters and tyros alike.

Six years ago, the legendary Russian grand master Kasparov, then world champion, attributed a certain inhuman sentience to IBM Corp.'s Deep Blue, a dedicated chess machine with hundreds of processors that made history by beating him. It is a measure of how far things have come that he must now pay similar respect to a commercially available program (albeit one running on up to 8 off-the-shelf microprocessors with as much as 8 GB of RAM).

To be sure, even the best computers still occasionally make moves so strange or stupid that no human, not even a beginner, could have made them. Yet no such moves, with "silicon" written all over them, cropped up in this match.

However, several bad moves certainly had "carbon" written all over them—the all-too-human mistakes of Kasparov. "DJ has so far passed the chess Turing test," wrote chess analyst Michael Greengard on chessbase.com. (Alan Turing, the British mathematician, famously proposed that any computer, communicating remotely, that could not be distinguished from a human being must be deemed intelligent.)

In the first three games, Kasparov got an advantage by exploiting the machine's shaky strategic insight. This manifested itself in Deep Junior's propensity to position pieces poorly (in games one and two) and allow the weakening of its king's position (in game three). Yet Kasparov won only the first of those three games. The computer's nerveless feats of calculation enabled it to exploit Kasparov's tactical mistakes to draw the second game and win the third. Kasparov got no advantage at all in the fourth and fifth games and was fortunate to draw them. In the sixth game, Kasparov got a rather better position, but—cowed by his earlier reversals—he agreed to a draw.

In the game the computer won, the third, Kasparov (playing White) sacrificed a pawn to develop a powerful attack, but Deep Junior's precise defense whittled down his advantage. Kasparov, by now short of time—each player is allotted a quota for each game—tried to force a draw. But on move 32, he miscalculated by moving his rook to the square h5 [see "Grid"].

Looking ahead, Kasparov expected Deep Junior to grab the White pawn at d4 with its queen, which would have allowed him to sacrifice his rook, taking the pawn at h7; after the Black king captures the rook, Kasparov's queen can take Black's knight, beginning an infinite series of checks that would lead to a draw.

However, Deep Junior instead found a canny alternative, taking the pawn with its knight instead of with its queen. The move required seeing ahead nine captures and recaptures, checks and threats, all in a forcing line—that is, one in which the defender typically has only one or two possible moves. Kasparov himself would surely have discovered this move, if he had been at his best, with plenty of time to think, rather than the 10 minutes he actually had to make his next eight moves. The computer not only had far more time left on its clock, it required far less time to see the combinations. And, of course, the computer is always at its best when it is a matter of brute-force calculation.

Two more checks by the White knight followed, but because of Deep Junior's shrewd 32nd move, they had to stop, given the impending counter-sacrifice of Black's knight, at b3, with check, opening the way for the Black queen to d1, checkmate.

Faced with the prospect of being down two pawns with no compensating attack, Kasparov clutched his head in disgust. After two more moves, he resigned, leaving the match tied. Neither side would win another game.

For an analysis of what the latest man-computer chess match says about the ongoing contest between human and machine intelligence, got to http://www.spectrum.ieee.org/WEBONLY/wonews/mar03/chesscom.html.