Under the rules of the match that the company has negotiated with the “Jeopardy!” producers, the computer will not have to emulate all human qualities. It will receive questions as electronic text. The human contestants will both see the text of each question and hear it spoken by the show’s host, Alex Trebek.

The computer will respond with a synthesized voice to answer questions and to choose follow-up categories. I.B.M. researchers said they planned to move a Blue Gene supercomputer to Los Angeles for the contest. To approximate the dimensions of the challenge faced by the human contestants, the computer will not be connected to the Internet, but will make its answers based on text that it has “read,” or processed and indexed, before the show.

There is some skepticism among researchers in the field about the effort. “To me it seems more like a demonstration than a grand challenge,” said Peter Norvig, a computer scientist who is director of research at Google. “This will explore lots of different capabilities, but it won’t change the way the field works.”

The I.B.M. researchers and “Jeopardy!” producers said they were considering what form their cybercontestant would take and what gender it would assume. One possibility would be to use an animated avatar that would appear on a computer display.

“We’ve only begun to talk about it,” said Harry Friedman, the executive producer of “Jeopardy!” “We all agree that it shouldn’t look like Robby the Robot.”

Mr. Friedman added that they were also thinking about whom the human contestants should be and were considering inviting Ken Jennings, the “Jeopardy!” contestant who won 74 consecutive times and collected $2.52 million in 2004.

I.B.M. will not reveal precisely how large the system’s internal database would be. The actual amount of information could be a significant fraction of the Web now indexed by Google, but artificial intelligence researchers said that having access to more information would not be the most significant key to improving the system’s performance.