Chinook is a computer program that plays checkers (also known as draughts). It was developed 1989-2007 at the University of Alberta, by a team led by Jonathan Schaeffer and consisting of Rob Lake, Paul Lu, Martin Bryant, and Norman Treloar.
Chinook is the first computer program to win the world champion title in a competition against humans. In 1990 it won the right to play in the human World Championship by being second to Marion Tinsley in the US Nationals. At first the American Checkers Federation and English Draughts Association were against the participation of a computer in a human championship. When Tinsley resigned his title in protest, the ACF and EDA created the new title Man vs. Machine World Championship, and competition proceeded. Tinsley won with four wins to Chinook's two, with 33 draws.
In a rematch, Chinook was declared the Man-Machine World Champion in checkers in 1994 in a match against Marion Tinsley after six drawn games, and Tinsley's withdrawal due to pancreatic cancer. While Chinook became the world champion, it never defeated the best checkers player of all time, Tinsley, who was significantly superior to even his closest peer.
In 1995, Chinook defended its man-machine title against Don Lafferty in a 32 game match. The final score was 1-0 with 31 draws for Chinook over Lafferty. After the match, Jonathan Schaeffer decided not to let Chinook compete any more, but instead try to solve checkers. At the time it was rated at 2814 Elo.
Chinook's program algorithm includes an opening book, a library of opening moves from games played by grandmasters; a deep search algorithm; a good move evaluation function; and an end-game database for all positions with eight pieces or fewer. The linear handcrafted evaluation function considers several features of the game board, including piece count, kings count, trapped kings, turn, runaway checkers (unimpeded path to be kinged) and other minor factors. All of Chinook's knowledge was programmed by its creators, rather than learned with artificial intelligence.