MENTALLY and physically tired, world chess champion Garry Kasparov needs to make a superhuman effort this weekend if he is to defeat the machine Deep Blue in the closing games of their absorbing rematch.
The contest is tied after four games, just as it was in their 1996 clash in Philadelphia, but the momentum is with the improved and modified IBM supercomputer following many exhausting hours at the board and an uncharacteristic passivity from the Russian grandmaster.
The turning point for Kasparov came the day after Sunday's second encounter when analysis revealed that he had resigned in a drawn position, a remarkable miscalculation that had never happened before to the man respected as the best player in the history of the ancient game.
Instead of maintaining the lead in the match, it was tied at one win each.
Two draws followed on Tuesday and Wednesday in which the system proved to be Kasparov's equal in almost every aspect of the game.
Many grandmasters and hundreds of chess fans want to see the creative, swashbuckling Kasparov style return to the board for today's fifth game, when he will play with the white pieces and the advantage of the first move for the last time in the $1.1 million contest.
The sixth and final game is tomorrow, when Deep Blue will play with white.
In the 12 years since becoming the youngest world champion in history at the age of 22, Kasparov has successfully defended world championship titles four times.
Deep Blue is an IBM RS/6000 SP parallel processor with specialised microchips for chess. It can examine hundreds of millions of chess positions per second or 50 billion possibilities in three minutes, the average time it takes for a human to make a move in classical chess formats in which the game can last several hours
The match, which is being held in a Manhattan skyscraper office complex, is part chess contest and part research project to help develop computers that can make complex, simultaneous calculations for applications such as weather forecasting, air traffic control and molecular dynamics.
