Strelka v2.0 released as open source

The strong and controversial chess engine Strelka has been released as open source.

The source is here: http://sdchess.ru/engines/Strelka_2_0.rar

The key postsfrom the chess software discussion groups seem to be this one where Vasik Rajlic, author of Rybka, claims Strelka has stolen from Rybka v1.0.

Anthony Cozzie, author of the strong engine Zappa, wrote a nice overview of what he saw in Strelka:

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I expected that Rybka was going to be a fast simple program with an obfuscated node count, but I had no idea just how right that was going to be. On my machine the 32-bit Strelka gets 1.2 million nps or so, which means a 64 bit compile would get 2.5M, or about 5X as fast as my poor little Zappa. In terms of knowledge, there is very little that is not in well known except for the material tables, which should be very fast. I'm also pretty amazed at how aggressively the search prunes. Not only will Strelka drop straight into the q-search on a depth-3 search search, but because it orders all captures first, it will reduce almost all noncapture/check moves.



Anyway, in my professional opinion Strelka is basically Fritz5 + history reductions + bigger (but not more) mobility/passed pawn terms + super-vasik-material evaluation. What's amazing to me is how well it works. I don't know whether to laugh at the silliness of all the speculation surrounding Rybka and how horribly wrong it was, or congratulate you for taking a completely different path than everyone else.
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US law seems to allow software to be decompiled and reverse-engineered if you pay for the software, so there's some chance that it is indeed legal to steal secrets this way, however it sure feels wrong. There have been discussions going on for years about the "secret sauce" in Rybka, and I alway wonder what closed source professional programs do differently from open source ones.