HOWZAT

Counters jump over opponents’ pieces to capture them, and those that reach the opponent’s end of the board become “kings” and can move backwards as well as forwards.

Chinook was developed by teaching a computer to use rules of thumb or “heuristics” to know what move to make in particular situations. It became so sophisticated that in 1994 it became the first computer to win the human world championship in any game.

In a contest against Marion Tinsley, who lost only three tournament games in four decades and is considered the best player of all time, Chinook achieved a string of draws before Tinsley withdrew with health problems and conceded.

The new version of Chinook is more powerful still: even Tinsley could not have beaten it. “To this day, I still get people saying that you would never have beaten Tinsley,” Dr Schaeffer said. “The program today would never lose to Tinsley or anyone else, period.

“The program can achieve at least a draw against any opponent, playing either the black pieces or the white. That checkers is a draw is not a surprise: grandmaster players have conjectured this for decades.

“I think we’ve raised the bar — and raised it quite a bit, in terms of what can be achieved in computer technology and artificial intelligence. “With Chinook, we’ve pushed the envelope about one million times more than anything that’s been done before.

“Solving checkers has been something of an obsession of mine for nearly two decades, and it’s really satisfying to see it through to its conclusion.”

Independent games experts said Chinook’s achievement was genuinely remarkable. David Levy, president of the International Computer Games Association, said: “It’s a huge accomplishment. It’s by far the most complex game ever solved.”

Jaap van den Herik, editor of the International Computer Games Journal, said: “This is a tremendous achievement — a truly significant advance in artificial intelligence.”

While chess is unlikely to give up its secrets to a computer soon, Dr Schaeffer is confident that other popular games will be “solved” by computers in the near future. “The disc-flipping game of Othello is the next popular game that is likely to be solved but it will require considerably more resources than were needed to solve checkers,” he said.

A poker program developed by the same team, known as Polaris, is also facing its first test next week, in a $50,000 challenge against two human professionals in Vancouver.