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" . I now wouldn't be surprised if it also makes improper use of OSS libraries.
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.
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.
On the other hand, if ChessBase is found (and ruled) to have distributed software illegally, the company and its executives might have another problem. I don't know the specifics of German law, but I believe that distributing software (or any product) illegally is actually a criminal offense (no longer a civil dispute). That could (theoretically/eventually) lead to criminal prosecution and who knows .. jail time?
There was only one legal way for ChessBase to do what it did (rebrand stockfish without attribution), and that was to acquire a (non-gpl) license from all the stockfish developers. That was almost certainly possible, for enough money. Stockfish developers could arguably sue for those lost licensing fees.
Presumably it's important to establish damages (at least in a US jurisdiction) because otherwise they wouldn't have standing to bring a lawsuit.
In the US there are statutory damages for copyright infringement ($50k per act of infringement, tripled if wilful) so you're entitled to that much without having to prove any actual damages.
(Part of the point of having a legal fee schedule is, I suppose, to put a damper on the prices of legal help, because, like in medicine, the demand is otherwise extremely inelastic: when you need it, you really need it. That does not appear to work. I wonder if there is an approach that would work.)
Secondly, there is a morality clause with regards to attorney fees, so usurious rates like some US attorneys charge are harder to achieve.
This doesn't mean German attorneys are cheap. It's just not quite as out of control as the US legal system. (Though attorney's professional bodies are obviously lobbying to make it easier to charge more)
The legal fee schedule does put a damper on attorney work, and more importantly, makes it somewhat easier to predict costs should you need an attorney. If it's enough of a damper is open to interpretation. I
Of course, if there's one thing that lawyers are less likely to do than cap the earnings of their profession, it's to devalue it entirely.
You could also increase supply by reducing the level of qualification needed to become a lawyer. Increased competition would drive prices down. That too is highly unlikely.
Also, in Australia, you'll only recover a portion in accordance with scale limits (party-party costs). Indemnity costs (100% recovery) is rarely awarded. What's the case in the US?
1. Lost profits due to the infringement.
2. The profits the infringer made from the infringement.
3. The amount the infringer would have had to pay to license the work to use the way they did it if they had requested such a license from the copyright owner.
The first one would likely not apply to something that is solely licensed under GPL, but the other two might, especially #2.
I'm curious how #3 is determined.
There is something similar in the US for patent infringement damages. That involves the court trying to determine what would have happened in a hypothetical negotiation if the patent owner had been willing to license the patent and the infringer had wanted to license the patent.
That can work because usually with patents you can compare to other patent in the same or related field that are about as valuable and have been licensed out. I don't think that there are a lot of open source world class chess engines that are dual licensed for proprietary use that a court could use for comparison.
They are normally from $750-30000 per work infringed.
The lower limit can be lowered to $200 if the defendant can prove that they were an innocent infringer (they were not aware and had no reason to believe they were infringing). The defendant has the burden of proof for this.
The upper limit can be raised to $150000 if the infringement is "willful". The statute does not define "willful". Courts have taken it to mean reckless disregard. The defendant knew they were infringing and did it anyway.
The jury decides where in the range you end up, and they certainly might take into account the magnitude of your infringement so 10000 downloads might cost you more than 1000 by convincing the jury to choose somewhere high from the range, but the cap on the total will be $30k (or $150k if it was willful).
Note that this means that willfully distributing 10000000 copies of one movies is going to be a lot better for the defendant than distributing a single copy each of 300 different movies, if the plaintiff elects to ask for statutory damages.
The 10000000 copies of one movie is just one work infringed, so you are looking at $150000 worst case.
The single copy each of 300 movies is 300 works infringed, so best case (assuming you are not an innocent infringer) is the minimal amount of statutory damages per work, $750, times 300 works = $225000.
(But remember that the plaintiff gets to choose between statutory damages and actual damages. If you've distribute 10000000 copies of their movie, they'll probably go for actual damages which could be considerably more than $150000!)
Too late to delete, but thanks for the tuneup.
(in German) https://www.cmshs-bloggt.de/gewerblicher-rechtsschutz/urhebe...
* I don't know what the opposite of a plain-tiff is
Complainant and Respondent
This case however brings two new (as far as I'm aware) questions to the table:
- Whether the permanent license revocation clause holds up
- Whether the neural networks is considered a part of the covered work (and must therefore be provided in "source" form, rather than just a trained network)
The second one is especially interesting, since the court will likely have to go into how far the GPLs coverage extends into other parts of a covered work.
The losers probably thought the license terms were just some of Stallman's psychodrama and not actual enforceable obligations.
The part about financial means stood out for me. All societies should work harder to ensure that money is not an impediment to obtaining justice.
Two brothers defrauded the government by forging signatures of the owners and notaries for the transfer of property deeds and took several hundred thousand Euros worth of land from various people.
My friend's family has been in court for 10 years trying to get it back.
The brothers mortgaged the properties to pay for litigation.
The real shit sandwich is that one brother died, and if the other brother dies, they start the proceedings all over again. If they win, it's purely in the name of justice; the lawyer will keep most of the money as payment for 10 years of litigation.
When I bought a house, all sorts of legal checks were required before I was allowed a mortgage. That seems like it would be standard practice.
Surprisingly, you can...
Of course, once it's time for a criminal to pay up, both they and the money mysteriously vanishes.
TL;DR, identity verification should be improved. Signatures are not working.
The bank isn't under any obligation to give you a mortgage. From their point of view they're lending you a big wedge of cash with the property as collateral, so they should be trying to satisfy themselves that the collateral is enough to cover the loan in case you default. If there's a non-negligible chance that the person they're lending the money to doesn't actually own the property (e.g. they're tied up in a legal dispute over ownership) then the bank has no collateral and is taking on a big risk.
> If a court does rule that the transfer was fraudulent, the bank can cancel the mortgage and demand immediate repayment.
What if the person doesn't have any means to pay back the mortgage? The bank has then just made a chunky loss. This is why the bank will typically do background checks on the property to establish ownership, condition of the property, environmental risks etc. (though this doesn't seem to have happened here, or the checks weren't overly thorough).
Obviously it could be different in the Czech Republic.
I'd assume someone like that existed there as well.
Doesn't mean it doesn't happen, of course.
I would assume that you should get the land and the bank can then sue the brothers to get their money back. Why should the mortgage be transfered to the original owners, they never agreed to it.
I'm just predicting the likely outcome.
Ah yes, the $80 Stockfish engine.
Microsoft lets any program use that UI: https://docs.microsoft.com/en-us/windows/win32/windowsribbon...
I've only seen a few programs take up the offer though. Probably because the style is almost synonymous with MS Office as you've noted
So a good program should look and feel similar to other programs
What do they mean by this?
You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11).
However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.
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.
Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, you do not qualify to receive new licenses for the same material under section 10.
Since Chessbase has not done that, Stockfish devs are no longer allowing Chessbase to use their code.
This simply reverts the code to copyrighted content, much like a book.
Like, if I ran Windows on a server and Microsoft revoked my license. Surely that's tested in a court at some point?
Windows comes with a click-wrap contract that you agree to when you install it, that restricts certain things you could usually do. So it's a bit of a bad example... but I'll use it anyways.
What does (generally, not legal advice, not a lawyer) need a license is making a copy of the software, i.e. installing windows onto your computer actually makes a copy, or making a copy of the installer for your friend - makes a copy. Just booting up the machine that already has windows installed on, that's (probably) not copyright infringement even if you don't have a valid license. It might be breach of contract depending on what contracts you have agreed to though! Physically giving your friend the computer with windows already installed on it, is similarly not copyright infringement. Cloning the hard-drive so you now have two hard-drives with windows installed, that's copyright infringement.
Using software is not one of the enumerated rights reserved to a copyright owner. Copying and distributing it are. So it's unclear whether a copyright owner has standing to sue you for using their software without a license. In the US there is conflicting caselaw, hinging on the legal status of the temporary copy made in the computer's RAM when a program is launched.
That they can sue is a non statement, you can sue for anything, but I don't believe it is obviously (or even likely) copyright infringement...
As far as I know it is like a book, if you have a copy you can read (execute) it, you just can't make new copies for your customers.
Whether or not that helps ChessBase... well... ya...
So like an ebook then. We don't have a good distinction in English between a) medium-length arrangement of words and punctuation and b) book.
Only CC0/WTFPL/Public Domain are renunciations of copyright.
Also, when it comes to code dedicated to public domain it is good to consider what wikipedia says about implied warranty: "The licensing process also allows authors, particularly software authors, the opportunity to explicitly deny any implied warranty that might give someone a basis for legal action against them." It is always good to include a clause saying that there is no warranty, implied or otherwise (unless of course you provide a warranty, which you probably should not do without restrictions on OSS code).
They say it's compatible, but not recommended.
"Unlike the Public Domain Mark, CC0 should not be used to mark works already free of known copyright and database restrictions and in the public domain throughout the world. However, it can be used to waive copyright and database rights to the extent you may have these rights in your work under the laws of at least one jurisdiction, even if your work is free of restrictions in others. Doing so clarifies the status of your work unambiguously worldwide and facilitates reuse."
As I understand it, you can't just waive copyright on your own work - copyright is something you get automatically in most jurisdictions on the planet. Licenses like CC0 and WTFPL are operating within the copyright regime - they use the laws to make your work behave as if it was not subject to copyright - but they can't actually make your work not copyrighted.
It's like a difference between simulation and reality. CC0, WTFPL, etc. are simulating a copyright-free reality on top of the copyright system. No matter how close to perfect they get, it's still a simulation, and copyright is the underlying runtime.
Seems inefficient, but I understand if thats their only remedy, as provided by their own license
I don't think that prevents somebody sympathetic (if such a person exists) from re-distributing it to Chessbase though.
Would this be legal?
But it would be a breach of copyright for Chessbase to distribute or modify the code, after their license has been terminated.
Open source chess developers warn about a commercial engine based on Stockfish - https://news.ycombinator.com/item?id=26185139 - Feb 2021 (130 comments)
I thought there were others - maybe someone will find one?
"In particular, the license states that if one redistributes a program derived from our work, the corresponding modifications of our sources and all information needed to build that program must be made available. Only after explicitly informing Albert Silver (the author of the net in Fat Fritz 2) of a license violation have matching C++ sources, but not the net weights, been made available. Obviously, we condemn the approach taken."
Should I be legally compelled to share the net weights of my trained NN?
If you have a non-GPL license to use and redistribute the data you use to train the neural net, I would imagine not.
Under GPLv3, the answer is explicitly clear:
"The output from running a covered work is covered by this License only if the output, given its content, constitutes a covered work."
In order for NN weights to be covered, the weights would need to be in themselves a derivative of a GPLv3-licensed work.
Training a NN on GPLv3 licensed training sets would (IMHO) make it a derivative work, that's what a lot of the Copilot uproar is about.
A forked project doesn't have the right to grant people licenses to code which they don't own.
Very good point.
The viral nature of the GPL and other copyleft licenses expressly allow this and put a healthy fear of improper OSS reuse and deployment in most rational software companies.
1. ChessBase was in violation of the GPL, but then cured the violation by releasing code (https://stockfishchess.org/blog/2021/statement-on-fat-fritz-...). But the post claims they refused to release the weights.
2. But the weights are already being released with the program they're selling. Otherwise, how would the program run? Why would they refuse, when they already distribute the weights with every copy of the program? I thought maybe Fat Fritz 2 was a cloud-hosted solution (weights aren't provided locally), but https://en.chessbase.com/post/running-leela-and-fat-fritz-on... seems to indicate it can run on a laptop with a GPU.
I suspect Stockfish may be trying to argue that whatever code was used to generate the weights is also covered under GPL, and that ChessBase is in violation because they refuse to release this code. I hope they don't try that argument, because it's certainly not true; you're free to train a chess engine however you want, insert the weights into a GPL'd program, and then are under no obligation to release the code to train the weights.
3. Setting aside the question of copyright entirely, it's unclear that Fat Fritz 2 is actually worse. Stockfish references https://www.sp-cc.de/ as an independent rating system, but if you look at the detail view (https://www.sp-cc.de/files/programs.dat) Fat Fritz 2 only seems to be compared to Stockfish 13 (210218) and not the latest versions of Stockfish.
I'm on Stockfish's side here, because I suspect ChessBase simply duplicated StockFish's training methodology and tried to pass it off as their own. (The engine's performance seems almost identical.) But I hope Stockfish has an airtight case for court. It'd be a bad idea to hinge the GPL violation on "they refused to release the neural net weight training code."
In the same way that, e.g. Windows can run from binaries, without distributing the source code? That is to say, the weights are in a binary format that is not amenable to re-use without decompilation and reverse-engineering.
Given that the chess engine in question is just a tweaked version of Stockfish, this will have a severe impact on their ability to sell their product.
I'm not sure how this would work with derivative code, though. I wonder if they could take a fork of StockFish, which is not StockFish and therefore subject to a different license agreement, and go on their merry way. I don't think that tactic would work (the original author can still claim copyright over the code from the forked repository, I believe) but it might be a possible defence? I think? Not a great one, though.
I don't see any other way ChessBase can get out of this, unless the court decides that the termination clause is unlawful for some reason.
They mean that the weights are not open sourced. If the weights are distributed separately and not considered part of the "Corresponding Source", that may not be a GPL violation, and the blog post does not imply that it is. (They only say that they condemn the approach.)
> 2. But the weights are already being released with the program they're selling. Otherwise, how would the program run? Why would they refuse, when they already distribute the weights with every copy of the program? I thought maybe Fat Fritz 2 was a cloud-hosted solution (weights aren't provided locally), but https://en.chessbase.com/post/running-leela-and-fat-fritz-on... seems to indicate it can run on a laptop with a GPU.
The GPL can be interpreted to require that all the input necessary to reproduce and run a functioning binary must be distributed. If the weights and engine are integrated in one binary, and not "all the source code needed to generate, install, and run the object code and to modify the work, including scripts to control those activities" is provided, that could be a GPL violation. This does not apply if the weights are distributed separately under a different license.
> I'm on Stockfish's side here, because I suspect ChessBase simply duplicated StockFish's training methodology and tried to pass it off as their own. (The engine's performance seems almost identical.) But I hope Stockfish has an airtight case for court. It'd be a bad idea to hinge the GPL violation on "they refused to release the neural net weight training code."
They may have terminated the license in response to the Houdini revelations which is another chess engine based on Stockfish that Chessbase has sold as original work, disguising its Stockfish origins in violation of the GPL.
As the GPLv3 says under Section 8  the license can be reinstated if "this is the first time you have received notice of violation of this License (for any work) from that copyright holder" - the first violation would have been Fat Fritz 2.
Build an opening repertoire from PGNs.
Drill that using spaced repetition (like Chessable)
Import all my games from Lichess and Chess.com
Tell me when I deviate from my repertoire in those games.
Do you know of a software or combo that can achieve that?
Also Opening Tree for bulk analysis:
They're both free and open source.
It stores your games and gives you an explorer for your games similar to what openingtree does.
Here is an example for the current world champion: https://www.chessmonitor.com/u/kcc58R9eeGY09ey5Rmoj/explorer
Does this wording seem extremely weird to anyone else?
According to the GPL:
> You may not propagate or modify a covered work except
> as expressly provided under this License. Any attempt
> otherwise to propagate or modify it is void, and will
> AUTOMATICALLY TERMINATE your rights under this License
Capitalization added by me. Maybe it's a nitpick, but it seems to me that the "termination clause" as people are calling it, isn't something you "invoke" or a sword you use to slay people who violate the GPL. It's an automatic process which you, the copyright holder, don't really control in any way.
In a technical sense yes, the GPL avoided giving rights holders an option to terminate. There’s no such thing as automatic enforcement of these things though (well, not for GPL, music industry is a different story), so it is not a big difference. I’m pretty sure you could just send a violator a fresh copy of the code and establish a new license agreement with them, so it’s still up to the rights holder if they want to continue.
Almost everybody skips reading the terms and licenses of things
In the chess case, the team probably assumed that open source meant “do whatever you want,” and nobody dug any deeper than that, and now they’re getting sued
Edit: the comments below say that they knew about the license issue for years
While the end user might be sloppy on checking the license aspect, developers certainly are aware at some stage, especially commercial developers by the time they create or modify their about dialog.
Yeah, nobody reads this stuff. I've even seen developers fail to understand the implications of the license they're applying to their own code and then get mad when people do things that are allowed.
Most people will not actually go to court over any of this stuff either. Surprising to actually see someone getting sued over licenses nobody reads.
"Non-starter" is a gross mischaracterization for GPLv3 for most companies, even most software companies, considering there is quite a bit of GPLv3 software in a modern GNU+Linux distro that they likely rely on.
Try and find a single major corporation in the world that is willing to bind it's proprietary intellectual property to GPLv3. It's a tribute, honestly, to that license that most companies realize that they have to go all-in on open-source (at which point GPLv3 is fine)
The UI is terrible, a sad relic from the MDI era. It's absolutely _not_ quick (you can constantly see it repainting, for example), search is extremely clunky, tools for match prep are awful, and it doesn't really have any good learning features. There's some vaguely interesting recent stuff like novelty mining but it's very limited (and why charge so much for database subscriptions only to make people do so much local eval?)
I dunno, I still pay for it because the database is nice to have, but I'm always astonished by its success. YMMV.
Can the developers do this? I was under the impression that when code is published on the web GPL licensed, the developers cannot retroactively withdraw the license...
Or perhaps they are withdrawing the license for all new code... To publish some code as "GPL, available for all except this person"? Is that allowed? Even if that were allowed, someone else could use their rights under the GPL to redistribute it to that person...
> 8. Termination.
> You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11).
> [...] reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license
which is what the Stockfish developers have now done. I.e. if Chessbase starts to comply now, it would be too late.
(n.b. National Chess Day is today)
Former comment at the time: https://news.ycombinator.com/item?id=12254911
Lower courts are usually not where you get good decisions in novel cases like GPL enforcement.
"developers of Stockfish have terminated their GPL license with ChessBase permanently"
"The license must not discriminate against any person or group of persons."
Thus, is Stockfish no longer DSFG?
Q14 on https://people.debian.org/~bap/dfsg-faq.html
My impression is that enacting the termination clause of GPL makes Stockfish non-DSFG.
If the Stockfish developers believe a party has broken the terms of a license, they can do any of:
* enact the termination clause, and thus make Stockfish non-DSFG
* raise a court case against the party for breach of license
The Stockfish developers happen to have done both.
"Notwithstanding this literal understanding of the license terms, the harshest constructions of the termination provisions of the GPL have not been enforced in practice."
Even if it was tested in one jurisdiction, it might not apply in others.
If I choose to grant a GPL license to only green-eyed people, would that meet DFSG's defintion of non-discrimination? By your argument, yes: the license itself is not discrimination.
Yet I do not think that meets the spirit of DFSG.
How practical is this, under GPL?
1. ChessBase began selling the Fat Fritz 2 chess engine.
2. It came to the attention of Stockfish developers that FF2 is a Stockfish derivative "with a few lines of code modification". 
3. Stockfish notified ChessBase of the violation and demanded that they comply with the terms of the GPL. ChessBase responded by releasing the source code of Fat Fritz 2, but not the neural net weights created for use and distributed with FF2. 
4. Key Stockfish developers regard the distribution of FF2 without the neural net weights used in creating the work to be a violation of their rights under the GPL. ChessBase (apparently) disagree - I don't see a press release on their website to confirm their take on this.
This question appears to hinge on whether the weights constitute part of a derived work under the GPL. This may depend on whether the weights are "output" from running a covered program. Under the GPL 3, the output of a program is only covered only if, given its content, it constitutes a covered work (i.e. a part of a GPL 3 covered program).
The exact technical details still aren't clear to me. If ChessBase is willing to release any software that actually ships with FF2 (e.g. the NNUE file) under the GPL, I think that would cure their violation even if they don't release the code used to produce the NNUE file. It's not clear to me whether or not they have been willing to do this (I'm not totally sure what's meant by "weights").
5. Regardless of this, Stockfish developers likely have the right to invoke the nuclear option (license termination). Even though ChessBase have ceased their license violations, a GPL 3 copyright holder may terminate your license under 2 conditions:
* If you have been notified of a GPL 3 license violation by the same copyright holder (for any work) before, and the copyright holder notifies you of the violation within 60 days after you cease to violate the terms of the license.
* If you do not cure your violation of the GPL within 30 days of notification, the copyright owner may terminate your license regardless of whether you have previously been notified.
6. There are two ways Stockfish potentially wins this lawsuit. Either
(1) they argue that violation of the GPL license is ongoing, and thus ChessBase have not cured their violation of the license within 30 days and therefore they are within their rights to terminate. This would hinge on the licensing status of the neural net weights, as discussed above.
(2) They argue that at least one Stockfish copyright holder involved in the lawsuit has notified ChessBase of a violation of the GPL 3 before, and thus has the unconditional right to terminate the license because ChessBase was notified within 60 days. This seems plausible enough given ChessBases's previous use of their code  but I haven't found any statement that outright says that they have previously notified ChessBase of a violation of their GPL 3 licensed work.
That's the feedback loop of a neural net.
The fuzzy part is if it counts as source code. for example, you can redistribute gpl code with additional proprietary data files for art.
Is it possible with GPL?
> Basically I can claim that it is I that committed the code under a pseudonym that matches someones real name. Also you can find someone’s namesake etc.
I mean, you can claim obvious falsehoods if you want, but especially doing so in court isn't going to be a good idea.
I don't see why they would need every last contributor. They only would need the contributors of the specific code that they allege was copied. That Stockfish contains other code by other contributors that may or may not have been copied would not be relevant.
Can they just do that? How can software really be considered free if the maker can later take away your permission to use it?
Is ChessBase violating the GPL3?
EDIT: oh, I should read the article. They are saying ChessBase modified the GPL software then redistributed it without the original attribution or copyright.
My non-expert impression has been that open source licenses and "licenses" that aren't ... explicit contractual agreements between parties (i.e. not just click through or some text in a download) do not have a particularly strong backing with law or case law. Whether or not you "can or can't" do something with regards to effectively making up rules that will be enforced by courts with a blob of text in source code or a check boxes on websites is still somewhat up in the air (somebody who knows things feel free to correct my impressions).
"Your honor, the defendant is distributing my copyrighted work without a license. Make him stop please."
Don't read that as lawyers never go to court unless they will win. This is obviously not true: there are many reasons to take a case to court knowing you will lose it. However if a case will be lost in court they will avoid court if possible.