Government agencies around the world depend on Cray's supercomputers, some costing $30 million or more, for sophisticated modeling and simulations for everything from weather to wars.

Advances in computer visualization - borrowed from engineering applications, atmospheric studies and, as always, Hollywood special effects - gave rise to a dazzling array of sophisticated modeling and rendering tools.

It may turn out that these questions can only be settled by experiment, or by sophisticated modeling of the neuron in the presence of a realistic ultrasonic wave.

No-migration petitions involve sophisticated hydrogeological and geochemical modeling.

Therefore more sophisticated modeling and algorithms have been developed to address the problem.

He shared with Joseph Ritchie, C.R.T.'s president, an expertise in sophisticated mathematical modeling, and Ritchie shared some computer programming.

Intelligent agents have been used before in research environments, but this is the first time such sophisticated behavioral modeling has been put in a video game, Dr. Johnson said.

Rick Lehner, a spokesman for the agency, said the military also had sophisticated modeling and simulation capability and was confident the interceptor would work.

"The initial studies in 1964 were conducted using the most sophisticated modeling," Mr. Cermak said, "and it's an approach that is still being used at wind tunnels today."

Using sophisticated mathematical modeling, they found that: