oreopoulos wrote:Maybe 20 years ago, movegeneration algorithm was important for an engine performance. Nowadays, can you claim something like that??
I think this decision is bad for chess engines and not for Rybka alone.
Its only bad for chess engines if their authors want to enter them into tournaments such as the WCCC. If you want to enter the tournament, you have to write the program yourself. You can't copy code from others and then pretend it was all your own work. Pretty simple, really.
The issue of licensing is completely separate from the issue of ICGA tournament rules. If you want to sell a commercial engine (or even distribute an open-source one), you have to either avoid using other people's code, OR simply respect whatever license agreement they have attached to their code.
Copyright law in most countries, protects the rights of whoever owns the copyright to that code (for chess engines, that is usually the author). If you want to use someone else's copyrighted code in your engine, you need their permission. This permission usually comes in the form of a license. As long as you follow the conditions of the license, you can use it. If you break the license conditions, then you lose your permission and you are now infringing the owner's copyright if you distribute their code (or a compiled engine containing their code, or some code derived from their code, or a compiled engine containing some code derived from their code...)
Rybka is a commercial program that (at least in some versions) apparently contained code derived from Fruit 2.1. Rajlich did not follow the terms of the GPL license of Fruit 2.1, so he may be liable for copyright infringement because he sold a derived work based on that code.