Responding to defeat with the pride and tenacity of a champion, the I.B.M. computer Deep Blue drew even yesterday in its match against Garry Kasparov, the world's best human chess player, winning the second of their six games and stunning many chess experts with its strategy.
Joel Benjamin, the grandmaster who works with the Deep Blue team, declared breathlessly: ''This was not a computer-style game. This was real chess!''
He was seconded by others.
''Nice style!'' said Susan Polgar, the women's world champion. ''Really impressive. The computer played a champion's style, like Karpov,'' she continued, referring to Anatoly Karpov, a former world champion who is widely regarded as second in strength only to Mr. Kasparov. ''Deep Blue made many moves that were based on understanding chess, on feeling the position. We all thought computers couldn't do that.''
As is his wont after a loss, Mr. Kasparov did not speak to reporters. But an ebullient Deep Blue team did.
''It feels unbelievably great,'' said Murray Campbell, an I.B.M. researcher who has been working on Deep Blue since 1989. Mr. Campbell said that even though Deep Blue defeated Mr. Kasparov in the first game of their first match a year ago, there were indications that neither the computer nor Mr. Kasparov had played very well.
''This time it earned the win,'' Mr. Campbell said. ''It played beautifully.''
Deep Blue had the advantage of playing the white pieces and moving first. The game developed slowly, with Mr. Kasparov playing cautiously, as he had said he would in the opening games, waiting for the computer to reveal its weaknesses.
''We're not seeing the Garry Kasparov I would play against,'' said Yasser Seirawan, a grandmaster who was providing live commentary on the game. ''He has clearly adapted his style. Does adapting make him a better chess player? I don't know.''
The problem for Mr. Kasparov yesterday was that Deep Blue showed no weaknesses. It held the white advantage throughout, playing a patient opening known as the Ruy Lopez, and in the endgame pressured Mr. Kasparov's king with rook and queen threats, never letting him breathe. At one point, Mr. Kasparov, appearing stymied, moved a bishop forward, and two moves later moved it back, a bit of wasted time that may have cost him.
''Garry was playing Black, plus he gave the computer two moves,'' said Lev Alburt, a grandmaster and former United States champion who was among the few chess experts who did not at least feign surprise. ''That's a big advantage. Any strong grandmaster would have won from that position.''
Mr. Kasparov looked uncomfortable almost throughout the game, squirming and furrowing his brow, holding his chin in his hands and staring bullet holes into the board.
''A lot of people were reminded of Karpov, who used this opening and then squeezed people to death,'' Mr. Campbell said. ''It kept control the whole game, and then squeezed and squeezed. Garry was suffering the whole time. It was an unpleasant position for him to play, and he had to hang on and hang on and hope for a mistake.''
The match is being played at the Equitable Center at Seventh Avenue and 51st Street in Manhattan, where the players are sequestered in a small, specially constructed studio on the 35th floor. Up to 500 spectators have gathered in a ground-floor auditorium, where they are watching the game on video screens and listening to the commentary of highly rated chess players like Mr. Seirawan. Journalists and a variety of chess grandmasters have been crowded in a room on the 49th floor.
In spite of all the separate quarters, a connecting bolt of electricity flew through the building when Mr. Kasparov stood after Deep Blue's 45th move and offered his hand to Feng-Hsiung Hsu, the I.B.M. technician across the table, resigning the game.
''Usually what computers do is create their own threats,'' Ms. Polgar said. ''But what this was doing was considering Kasparov's counter-play.''
That amounts to strategic chess, playing against a hypothetical future, which computers had thus far not accomplished. Whether Deep Blue can continue to do so is uncertain. In the third game of the match, scheduled for 3 P.M. Wednesday, Mr. Kasparov will play White. And he will be angry.
''We really have to watch out for that,'' Mr. Campbell said. ''Last year he came back and whupped us.''