An IBM computer displayed a few quirks but played to a draw on the opening day of a man vs. machine showdown with two human champions of the popular US television game show Jeopardy!.
"Watson," a supercomputer named after the founder of the US technology giant Thomas Watson, and human contestant Brad Rutter each had $5,000 after the first day of the three-day match.
The other human player, Ken Jennings, was trailing the pair with $2,000.
Watson, represented on stage by a large computer monitor, was frequently quicker to the buzzer than Rutter and Jennings, correctly answering questions in its artificial voice.
Jeopardy!, which first aired on US television in 1964, tests a player's knowledge in a range of categories, from geography to politics to history to sports and entertainment.
A dollar amount is attached to each question and the player with the most money at the end of the game is the winner. Players have money deducted for wrong answers.
In a twist on traditional game play, contestants are provided with clues and need to supply the questions.
Watson receives the clues electronically by text message at the same time as they are revealed to the human contestants. The first player to hit the buzzer gets to answer the question.
Watson showed an impressive grasp of the Beatles songbook.
"What is Maxwell's silver hammer?" replied Watson to the clue "Bang, bang, his silver hammer came down upon her head," a reference to the Beatles song.
"What is Eleanor Rigby?" Watson answered correctly to the clue "She died in the church and was buried along with her name, nobody came."
Watson at one point built up a commanding lead with $4,000 to $200 each for Rutter and Jennings.
But the machine then began to slip up, oddly repeating a wrong answer to a question Jennings had already answered incorrectly.
Jennings wrongly identified the 1920s as the decade during which the crossword puzzle and the Oreo cookie were introduced.
Given its chance, Watson also said in the 1920s.
"No, Ken said that," Jeopardy! host Alex Trebek admonished Watson.
Rutter then answered correctly -- the 1910s.
On another question, about a one-legged US Olympic champion, the clue was "It was the anatomical oddity of US gymnast George Eyser who won a gold medal on the parallel bars in 1904."
Watson replied "What is a leg?" instead of "What is missing a leg?"
"Watson's very bright, very fast but he has some weird little moments once in a while," Trebek said.
Watson, which is not connected to the Internet, plays the game by crunching through multiple algorithms at dizzying speed and attaching a percentage score to what it believes is the correct response.
Watson, which has been under development at IBM Research labs in New York since 2006, is the latest machine developed by IBM to challenge mankind -- in 1997, an IBM computer named "Deep Blue" defeated world chess champion Garry Kasparov in a six-game match.
Developing a supercomputer that can compete with the best human Jeopardy! players, however, involves challenges more complex than those faced by the scientists behind "Deep Blue," according to IBM researchers.
Watson uses what IBM calls Question Answering technology to tackle Jeopardy! clues, gathering evidence, analyzing it and then scoring and ranking the most likely answer.
"You are about to witness what may prove to be an historic competition -- an exhibition match pitting an IBM computer system against the two most celebrated and successful players in Jeopardy! history," Trebek said to kick off the show.
Jennings holds the Jeopardy! record of 74 straight wins while Rutter won a record $3.25 million on the show.
The winner of the Jeopardy! showdown is to receive $1 million. Second place is worth $300,000 and the third place finisher pockets $200,000.
IBM plans to donate 100 percent of its winnings to charity. Jennings and Rutter plan to give 50 percent of their prize money to charity.
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