3 ms·

I haven't followed computer chess for a few years, so wasn't aware there was such a growing controversy, especially considering how dominant Rybka has been(or w

by sireat 15y ago

I haven't followed computer chess for a few years, so wasn't aware there was such a growing controversy, especially considering how dominant Rybka has been(or was). Maybe someone who is more familiar with the case can explain what happened to warrant such an action? Crafy(free/open source though not GPL) by http://en.wikipedia.org/wiki/Robert_Hyatt http://en.wikipedia.org/wiki/Robert_Hyatt has been one of the cornerstones in computer chess. I am sure most aspiring computer chess programmers have looked at its source and techniques. Fruit I also believe was open source(not sure what licence). Now, both Crafty and Fruit are very strong GM level programs on a modern computer but are far from being the best. In fact, I(a lowly FM) routinely was able to find flaws in their algorithms (especially Crafty) and draw or win games using standard tricks(closed openings, passive no obvious weakness openings, etc.). Rybka is pretty much immune to such anti computer chess shenigans. It has a much better "knowledge" of human chess somewhat explained by fact that Rajlich is an IM. In fact, Rybka stood heads and shoulders above all the other contenders for a while.

nas 15y ago
There have been rumblings for years, at least since Strelka came out. I happen to think the GPLed code of Fruit was the best thing to happen to computer chess for a long while (thank you to Fabian). IMHO, cloning is not a bad thing since allows incremental improvement by multiple authors. Cloning without respecting the license of the source, however, it not okay and it seems clear now that's what Rajlich did.
- sireat 15y ago
  Thank you for the explanation! I took the time to read the official report on Rybka Investigation and Summary of Findings for the ICGA http://www.chessvibes.com/plaatjes/rybkaevidence/RybkaInvestigation.pdf http://www.chessvibes.com/plaatjes/rybkaevidence/RybkaInvest... For those interested in the issue, I recommend you read the report, as well. Some real heavies weight in on the issue including Ken Thompson. All are in agreement that early versions of Rybka show disturbing similarities to Crafty and then Fruit(this is when the big jump in rating performance was made). Rajlich has continued to claim that his code is all original which is highly doubtful. To me the real damning evidence was by Hyatt, which showed that the early version of Rybka has whole bunch of useless code from Crafty, which Hyatt had used: "Summary: Pre-Rybka 1.6.1 contains much identical code to Crafty, even including large blocks of code with obsolete code inside them, and code that performs tests that make no sense today (code that was left in Crafty by accident, by Robert Hyatt, also shows up in Rybka 1.6.1)." Off course, most of the code must be gone by the later versions, but it is seriously in such a bad taste to be so disrespectful to other programmers.
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by sireat 15y ago

nas 15y ago

There have been rumblings for years, at least since Strelka came out. I happen to think the GPLed code of Fruit was the best thing to happen to computer chess for a long while (thank you to Fabian). IMHO, cloning is not a bad thing since allows incremental improvement by multiple authors. Cloning without respecting the license of the source, however, it not okay and it seems clear now that's what Rajlich did.

sireat 15y ago
Thank you for the explanation! I took the time to read the official report on Rybka Investigation and Summary of Findings for the ICGA http://www.chessvibes.com/plaatjes/rybkaevidence/RybkaInvestigation.pdf http://www.chessvibes.com/plaatjes/rybkaevidence/RybkaInvest... For those interested in the issue, I recommend you read the report, as well. Some real heavies weight in on the issue including Ken Thompson. All are in agreement that early versions of Rybka show disturbing similarities to Crafty and then Fruit(this is when the big jump in rating performance was made). Rajlich has continued to claim that his code is all original which is highly doubtful. To me the real damning evidence was by Hyatt, which showed that the early version of Rybka has whole bunch of useless code from Crafty, which Hyatt had used: "Summary: Pre-Rybka 1.6.1 contains much identical code to Crafty, even including large blocks of code with obsolete code inside them, and code that performs tests that make no sense today (code that was left in Crafty by accident, by Robert Hyatt, also shows up in Rybka 1.6.1)." Off course, most of the code must be gone by the later versions, but it is seriously in such a bad taste to be so disrespectful to other programmers.

deleted 15y ago

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