Zappa (Chess engine)

Zappa, Zap!Chess or Zappa Mexico, is a UCI chess engine written by Anthony Cozzie, a graduate student at the University of Illinois at Urbana-Champaign. The program emphasizes sound search and a good use of multiple processors. Earlier versions of Zappa are free (though not open-source software) and the current version (Zappa Mexico) is available at Shredder Computer Chess.

Zappa scored an upset victory at the World Computer Chess Championship in August, 2005, in Reykjavík, Iceland where it won with a score of 10½ out of 11, and beat both Junior and Shredder, programs that had won the championship many times. In the speed chess portion of the tournament Zappa placed second, after Shredder. Zappa's other tournament successes include winning CCT7 on the Internet Chess Club (ICC) and defeating Grandmaster Jaan Ehlvest 3-1.

In Mexico in September 2007 Zappa won a match against Rybka by a score of 5½ - 4½. Many commentators had predicted a slew of draws based on the strength of the engines, but the differences in style provided an interesting match with several decisive games and many fighting draws. For some time, Zappa was considered one of the two strongest commercially available chess programs; see engine rating lists like CCRL for current rankings. Some speculate that Zappa's more efficient SMP parallel search could make it stronger on enough processors.