GPL issues and the end of the Chess Engine Controvesy

This is all over the internet over the last couple of days

Rybka Banned

And the forums are full of people discussing and commenting, here is the Rybka forum:-

http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=22232

I think the main problem is that the Engine was entered into the World Computer Chess Championships when it was first released, for version 1 and 2, and at this stage it still contained code from 2 influential Open Source programs. The rules of the International Computer Games Association required that the contenders admitted when their programs were based on other sources, and this was not admitted by Rybka. After a release of a decompiled version it was found that Rybka was very similar to an engine named fruit, and also contained codes from Crafty. So eventually after more than 5 years Rybka has been disqualified based on accumulated evidence.

There is also the problem of the GPL (General Public Liscence), which requires that if GPL codes are used in a program that the source of the new program should also be released, and the authors given credit. This was not the case with Rybka however.

An interesting case is the fact that an Engine named IPPOLIT was released that claimed to be stronger than Rybka. The Author of Rybka, Vasich Rajlich claimed that the IPPOLIT sources were his code and that it was stolen from his computer or decompiled from a Rybka executable. It is interesting that since he claimed this on his forums he could arguably be in accordance with section 6.b of the GPL. A look at the site for IPPOLIT shows that the group responsible for the release call themselves the Decembrists (Russian revolutionary link) and claim to be waging a software war against the capitalists. This could in fact be a clear contempt for the GPL because after all GPL code is usually free.