Chinook Checkers Software Program – The Origins of Chinook Software

Chinook is by far the most famous checkers software program in the world. It was developed in 1989 by Jonathan Schaeffer, who started out working on a computer chess program, but later decided to work on a computer checkers program instead.

Along with Schaeffer, the team that was responsible for the development of Chinook checkers included Norman Treolar, Robert Lake, and Martin Bryant. Treolar served as the resident checkers expert of the team, and was primarily responsible for the program’s evaluation function, as well as its opening book. Lake, for his part was tasked with compiling the program’s endgame databases. Bryant would join in later on in the project, and was responsible for writing a very comprehensive opening book for Chinook. In addition to this team, a number of graduate students were also involved in the project.

Chinook was notable in that introduced the world of computer checkers to something that had not existed previously: endgame databases. The Chinook development team was responsible for producing databases that gave computers exact knowledge of all the positions with 8 pieces or less on the board in the form of win/loss/draw. Up until the release of the Chinook checkers software, the endgame databases for chess were computed as distance-to-win databases.

The win/loss/draw scheme implemented by the Chinook checkers software database is particularly noteworthy in that considerably less information has to be stored, which makes it possible to compress databases to an even greater degree. This is an important consideration if any user wishes to access the database during a search. The 8-piece database would later turn out to be approximately 6GB in its compressed form. By most accounts, the Chinook endgame database was then largest endgame database ever computed.

Like the early checkers software program developed by Duke University programmers, the development team of Chinook checkers software wanted their program to play against the then checkers world champion, Marion Tinsley. While the Duke University team’s match against Tinsley failed to materialize, Jonathan Schaeffer and his staff did manage to secure a match with the world champion in 1992. Unfortunately for them, the Chinook checkers software lost the match with 2 wins and 4 losses.

It must be said though that the program did not have the 8-piece database in place at that time. By 1994, the program did have the 8-piece database implemented, and a rematch with Tinsley was rescheduled. Tinsley however was suffering from poor health at this time, and forfeited the match as a result with 6 games that ended in draws. Chinook was later retired, although you may still download Chinook checkers on many web sites today.