Its various parts live in this ftp directory . There's also a Mac Crafty port. I consider it the best available starting point for any research chess programs which can make do with alpha-beta search. A free chess program with a simple form of opening-book learning. It runs under Windows, DOS, or unix.
Source code is available.
A unix chess program, which learns as of version 3.0. It is not as strong as crafty, but its evaluation learning feature is the most impressive around. Source for various versions is available in this ftp directory . The program has two forms of learning. Opening book learning remembers losing moves and stores them into the hash table before a search begins.