The computer chess engine Rybka has been sensationally stripped of its multiple World Computer Chess Champion titles and banned from competing in future events.
The International Computer Games Association (ICGA) took the action after an investigation into claims Rybka was a derivative of other chess engines.
The decision by the ICGA comes after suspicions of cloned computer engines led to the formation of the ICGA Clone and Derivative Investigation Panel.
The Panel investigated long-standing rumours that Rybka programmer Vasik Rajlich (pictured) used programming code in the Rybka engine that was copied from the engines Fruit and Crafty without credit being given.
The report's findings are damning, and can be read in full here. Excerpts from the conclusions and recommendations are below.
Rybka 1.0 through 2.3 contain nearly identical evaluation functions to Fruit 2.1. The evaluation overlap between Rybka 1.0 beta and Fruit 2.1 is 74.4%. Between Rybka 2.3.2a and Fruit 2.1 the overlap is 64.3%. These are much, much higher than any other programs examined (which average about 30%).
Early pre-Rybka 1.0 beta versions used a great deal of Crafty code and functions, which indicates a continuing use of other program code by Vasik Rajlich.
Vasik Rajlich’s claims of complete originality are not borne out by the facts. Rybka’s rapid strength growth (over 800 ELO in about one year) is largely due to copying evaluation terms and programming methods from Fruit 2.1. Rajlich’s claim that “Rybka has a very original search and evaluation framework” is false.
None of the ICGA Tournament entry forms submitted by Vasik Rajlich indicated that much of Rybka’s code was based on Fruit 2.1 (and earlier versions on Crafty). This is in violation of the ICGA Tournament Rules. Suitable punishment is:
● to strip Rajlich of all ICGA Tournament Titles and,
● force the return of trophies and prize funds to the ICGA and,
● ban his programs from future competitions until he can satisfy the ICGA that they are no longer derivatives and that he has satisfied the conditions of any other penalties the ICGA imposes.
● encourage other tournaments (Leiden, Paderborn, CCT, TACCL, etc.) to disallow the entry of Rybka until it is proven “clean”.
So far there has been no response from Vas Rajlich to the decision.