Chinook: Twenty Years Later

Edmonton: On August 17, 1992, for the first time in history a human sat down to play a computer for a world championship title. I was privileged to be part of that historic event: man versus machine for the World Checkers Championship.

In the summer of 1989, I started writing a checkers-playing program, the knee-jerk reaction to the poor result of my chess program in the 1989 World Computer Chess Championship. After two months of intense work, the program, christened Chinook, competed in the Computer Olympiad. To my delight, it won the gold medal. That success inspired me and I spent most of my 1989-1990 sabbatical working on the program.

In August 1990, Chinook competed in the premier section of the U.S. Championship ending up in second place. First place was taken by the World Champion, Dr. Marion Tinsley. In the seventh round of the event, Tinsley and Chinook squared off in a four-game match – all draws. This was the first time in history that a human world champion had played a non-exhibition event against a computer in any game.

By coming second, Chinook earned the right to play Tinsley for his title. The match took place in August 1992 in London, England. The following description of that event has been taken from my book One Jump Ahead (Springer-Verlag, 2007).

After making the first three moves of the checkers game, the arbiter, Con McCarrick of Ireland, reaches out and starts White’s clock running. The White pieces are commanded by a tall, slim man dressed in a modest green suit, tie held in place by a clip with “Jesus” spelled out in colored stones. He pauses for a moment, makes his move, and then presses a button that stops his clock and starts Black’s. His opponent, playing the Black side, immediately captures a piece. Just two friends playing a game of checkers, or so it seems.

There is a flurry of camera flashes as photographers jockey for position. After five minutes of this, McCarrick indicates that the time for picture taking is over; it’s now time for the players to think. As the reporters withdraw, the field of view for the spectators widens, and they can see not just the adversaries, but a computer terminal perched beside the Black player. On a large screen overhead, a realistic-looking white hand occasionally reaches out and makes a move on a computer-generated board. Once complete, a sinister-looking black hand makes the next move. Back and forth the two hands move on the screen, mirroring the moves played between the two combatants. White and black, metaphors for good and evil. The careful observer notes that both hands have a wedding ring on the second finger from the right, and the second finger from the left is bent, as if it has been in an accident. Realism versus animation, metaphors for man and machine.

The White player, Dr. Marion Tinsley, is clearly the crowd favorite. He is a young-looking sixty-five years old. At the start of the game he is relaxed and smiling, confident about the outcome, seemingly oblivious to the obvious tension that fills the air. The day before, at the opening ceremony, Tinsley gave a speech in which he said, “A reporter over here said a while ago, ‘You can’t lose, can you?’...right now I am just free of all stress and strain because I feel I can’t lose.” Dr. Tinsley is St. George and his opponent is the dragon. Confidence is a knight’s greatest asset. Without it, all is lost from the start.

Tinsley (right) and Schaeffer (left) squaring off for the World Checkers Championship (1992)

Moving the Black pieces is Dr. Jonathan Schaeffer, whose appearance is unbefitting for his role as the dragon. At thirty-five years old with brown curly hair and looking uncomfortable in a suit jacket without a tie, he appears to be ill at ease playing the moves. While Tinsley exudes confidence, Schaeffer seems hesitant and unsure of himself. Each move is double-checked, as if he isn’t sure how to play the game. In fact, Schaeffer is a novice player at best. Yet surprisingly, he’s here playing for the highest honor in the world of checkers—the world championship.

Chinook team (August 1992). From left to right: Duane Szafron, Joe Culberson, Paul Lu, Brent Knight, Jonathan Schaeffer, Rob Lake, and Steve Sutphen. Our checkers expert, Norman Treloar, is missing.

If you watch the participants onstage closely, you notice that every time Tinsley makes a move, Schaeffer reaches over to a computer keyboard, types a few key strokes, and then stares, not at Tinsley or the checkerboard, but at the computer screen by his side. The screen is at an angle so that only Schaeffer can read the contents; Tinsley is forbidden to look at it. Sometimes Schaeffer’s eyes wander off the screen and stare intently at his adversary. Tinsley pays no attention; he is lost in the world of checkers, as move sequences and checkers patterns mingle in his mind. Abruptly, something interrupts Schaeffer’s stare, and after a quick glance at the computer screen, he reaches out and plays a move. Other than relaying moves to and from the computer screen, he hardly ever looks at the checkerboard.

On the other side of the room a large refrigerator-like box stands alone, shunned by everyone. Yet every time Schaeffer interacts with the keyboard a panel of lights on the box starts dancing, as if excited by the contact. If you listen closely you can hear the hum of fans inside, keeping the contents cool, and a noticeable clicking sound resembling that of a Geiger counter. Few in the room know that the “box” is a $300,000 state-of-the-art Silicon Graphics computer. Even fewer care that the machine actually contains eight computers, all working cooperatively to solve a problem: find the best move to play in the game.

It is August 17, 1992, and the venue is the five-star Park Lane Hotel in central London, England. Dr. Tinsley is defending his world championship title against the computer program Chinook. Dr. Schaeffer, a duffer checkers player by his own admission, is just babysitting the program. His role is solely to relay moves between the board, which is the battleground, and the computer.

In the physical domain machines have been superior to man for many decades. Would you want to run a race against a car? Would you want to compete against a forklift at weightlifting? But in the mental domain humans remain supreme. For the first time in history a computer has earned the right to play for a human world championship. Man, confident with his God-given gift of intelligence, is being challenged by a computer, a mere machine. Man the creator is being challenged by his offspring the computer.

Are we witnessing history in the making? Will the electronic computer master mankind, his maker? Can a computer win the world checkers championship?

Where have the years gone? Surely it can’t be twenty years! On April 22, 2012, I held a reunion event for the members of the Chinook team that were still living in Edmonton. Compare the photos of the team from 1992 and 2012. We are just as young looking today as we were back then, despite the faulty camera that makes my brown hair look gray.

Chinook team (August 2012). From left to right Steve Sutphen, Duane Szafron, Jonathan Schaeffer, Rob Lake, and Paul Lu.

What happened in the match? That’s the subject of a future posting.