Note that it’s legal to sell stockfish as long as you’re compliant with GPLv3. ChessBase seems to be compliant.
Stockfish argues that ChessBase isn’t compliant because they refuse to release the weights. But this makes no sense; the weights are distributed with every copy of Fat Fritz 2. (Otherwise, how would the program run? It’s not cloud-based, as far as I can tell.)
Stockfish may be trying to say “you must open source any training code used to make the weights.” But this claim falls flat; you could use this same argument to say that any GPLv3 codebase must be fully open source in order to sell it, including all DLLs used by the program.
Stockfish seems to be saying that they have grounds for lawsuit because they have terminated ChessBase’s license. But GPLv3 doesn’t give you the ability to terminate a license arbitrarily; it requires you meet some specific criteria, and it’s unclear that ChessBase meets it.
I think it’s lame that ChessBase sold stockfish for $80. But that’s different than being illegal, and we should worry about the precedents set here.
No. The first license violation was that ChessBase released FF2 without source code for their modified Stockfish, and without the GPL license. This was later fixed after we reported it. The second license violation was Houdini, which contains Stockfish code, and even today is not a available under the GPL.
This reasoning isn’t correct.
The weights may be as object code not as source. Simply saying the program runs doesn’t mean you’ve distributed the weights anymore than it means your distributed the code.
Last time this came up people pointed at the installation information clause
> “Installation Information” for a User Product means any methods, procedures, authorization keys, or other information required to install and execute modified versions of a covered work in that User Product from a modified version of its Corresponding Source. The information must suffice to ensure that the continued functioning of the modified object code is in no case prevented or interfered with solely because modification has been made.
> Corresponding Source conveyed, and Installation Information provided, in accord with this section must be in a format that is publicly documented (and with an implementation available to the public in source code form), and must require no special password or key for unpacking, reading or copying.
https://github.com/official-stockfish/Stockfish/blob/sf_14/C...
Unless your license has been terminated by the copyright holders, in which case you cannot be compliant with the license because don't have a license to distribute the material at all.
> Stockfish argues that ChessBase isn’t compliant because they refuse to release the weights.
I haven't seen them argue this anywhere. You've linked to their previous statement in which they only say that they "condemn" the fact that the weights are not being released.
The announcement says that they've filed the lawsuit "to enforce the consequences of the license termination" because "ChessBase is ignoring the fact that they no longer have the right to distribute Stockfish, modified or unmodified, as part of their products."
> But GPLv3 doesn’t give you the ability to terminate a license arbitrarily; it requires you meet some specific criteria, and it’s unclear that ChessBase meets it.
You seem to be talking about this paragraph in the GPLv3 (https://github.com/official-stockfish/Stockfish/blob/sf_14/C...) :
"Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice."
However, this is not ChessBase's first violation. They've also tried to pass off Houdini as original work: https://shop.chessbase.com/en/products/houdini_6_pro_multipr...
Houdini 6 is also a stockfish clone. https://chess.stackexchange.com/questions/29181/is-houdini-6...
> I think it’s lame that ChessBase sold stockfish for $80.
This case is a bit different though: Chessbase (unlike RH and RMS) didn't tell anyone their product was open source, but pretended it was their own proprietary work and that it was better than the leading open source engine that it was stolen from.
But I'm just wading into this subject matter, so others chime in if I'm missing something :)
It's very clear from the story that it's the first one: they're not compliant with the GPL. At least that's what the Stockfish authors are claiming. They're pretty obviously acting in good faith and appear to be correct in their claim. ChessBase haven't laid out their side of the story other than their marketing materials saying "we developed the software in house and it's better than that open source stuff" and I wouldn't expect them to have a defence based on anything other than technicalities. You won't be seeing a blog post from them, because their lawyers have told them to say nothing.
> which means your customers could give it away for free if they so choose
ChessBase is selling the software, and they aren’t getting undercut because they are not redistributing everything the customer needs to rebuild it from source. It will be interesting to find out what that is (neural net weights, or whatever) and whether the court upholds that this is not copylefted under the GPL.
If this company has two products that under the hood seem to rely heavily on open source but they don't mention it, then it sounds this is their business model.
German court does care way too much for the "Urheberrecht" -- copyright -- and this is clearly a violation of it.
If they would let this go through, nobody would take the German court serious again, and there is too much interest in not letting that happen.
In any case, they also sell a music software called "Ludwig 3" [1]. I now wouldn't be surprised if it also makes improper use of OSS libraries.
[1] http://www.komponieren.de/arrangieren.html