OpenChess

From Felix Kling, in the comments on ChessVibes.com

Felix Kling on March 31st, 2010 02:35

@anderson: Only Vas can answer those questions, again, I’m no programmer.

@blueofnoon: In this case writing such an engine would be an incredible amount of work if you would start from scratch. Wouldn’t that make it unlikely that the author uses fake names? This can’t be compared with little programs.

@KingTal: See my first argument: Why should anyone who has to work like hell to create such a program want to use such childish fake names? Which logical explanation could you offer for this?

@alpha123. Easy. They added quite some stuff to try to obfuscate the cloning, some tables Larry added to Rybka are slightly modified and such things, some algorithms are added, some are removed. It’s actually easy to create an engine with totally different output. About the big effort: Well, it’s not the first time. See Strelka. About the UCI parser: I’m no programmer, there may be classical examples or not many alternatives for that. However, such things can hardly be considered real inventions of a program. About the evaluation tables: I don’t know any details about it. But I don’t see why I should trust Mr. Hyatt more than Vas. Afaik Fabien never did such accusations and everything seems fine for him, so even if programmers took stuff from Fruit (and it’s clear that all major programmers had a good look at it) I don’t see a reason to consider any modern engine a fruit clone. again, I don’t know the Rybka sources and the only one who could answer that question is Vas.

Now I read that Fabien as the owner of Fruit didnt take offense by Rybka code. Reasonable or not what is exactly your business, of you, Bob and these two "known" obfuscators, to be further busy in the anti-Rybka campaign or coalition? What legal sense this all does have??

Fabien is not interested, so I am not interested too. I just show the similaries.

Fabian's final word on the influence of Fruit in Stelka was very soft:
"No worries as far as I am concerned.
Ideas are not a legal property.
The code was rewritten so it's OK with me.
Tournament organisers might think differently."

There is a controversy about the chess engine Strelka. It is clear that Stelka has used ideas from Fruit, but also that Strelka has been extensively rewritten (for instance, it uses a bitboard approach and has a huge amount of table driven decisions).

I have looked at the source and I would say that it seems sufficiently different to call it an original engine of its own right. The line of what is obvious inspiration and what is copying may not be as clear to others as it seems to me.

And also this:
When I reviewed the code, the most striking similarity I saw was in some of the structures. In the code, how it was actually processing the data, things looked to be rather different, but the underlying data structures showed a clear lineage of fruit (I am sure you will see the same thing).

It is up to you to decide if the use is fair use or not, I think. All of the people who looked at the code so far do not have the true intimacy with Fruit that you do for obvious reasons. Cosmetic changes could easily fool us.

The use that he makes of tables is a very good idea that I have championed for a long time. I think (even more) that it should be taken further. We can write code generators to generate different “perfect” code for every board position.

From: Fabien Letouzey [mailto:fabien_letouzey@hotmail.com]
Sent: Wednesday, April 16, 2008 12:54 AM
To: Dann Corbit
Subject: RE: Tempest in a teapot

[...]
No worries as far as I am concerned.
Ideas are not a legal property.
The code was rewritten so it's OK with me.
Tournament organisers might think differently.

I cannot say a definite yes or no ...

Fabien also see no problem with strelka based on Dann Corbit's code

Vas has never denied that he learned a lot from Fruit code and that he went through it with a fine tooth comb from top to bottom. He also gave an estimate to how much that information added to the strength of Rybka. Using general ideas and writing your own original code learnt from ideas is NOTHING like stealing and copying and pasting someone else's work and claiming it as your own. Even Fabien has mentioned that he had no problem with it since it was entirely re-written in a different format. After all ... that was the original intent of Fabien when he released Fruit code. [...]

2) The fact that you don't know if there possible is an agreement between Vas and Fabien that allows Vas to use Fruit code and that both gentlemen also decided to keep that silent. Maybe Vas even paid Fabien for the service. Seems such a natural explanation and if true you better stop your research. Why not research this as first?

Maybe there is some non public agreement between them. Maybe Fabien even works now in the Rybka team. Can we know?