Stockfish Blog

In case it's not clear, this is the TCEC (http://en.wikipedia.org/wiki/Thoresen_Chess_Engines_Competition), widely regarded as the "world championship" of computer chess. This is the superfinals, between Komodo (http://komodochess.com/) and Stockfish (http://stockfishchess.org). It just began at the time of posting, it's a best-of-48 and will likely last 2-3 weeks.

I'm not sure Atwoods whole point about computation power: If AlphaGo was intimidating today, having soundly beaten the best human Go player in the world, it'll be no contest after a few more years of GPUs doubling and redoubling their speeds again. In the AlphaGo paper they said their cluster version (with the 170 GPUs Atwoods mention) were the limit of what hardware could do for their algorithms. They tried using much larger clusters, but it didn't really improve performance. This actually fits his point that for chess, most of the performance gain over the last ten years has come from better algorithms. In particular for chess, better tuning of variables, through projects like fishtest (http://stockfishchess.org/) It seems like many of these problems can only be solved using algorithms with require a certain amount of computing power. However once we've reached that particular amount of power, further progress really lies in the algorithms.

It's possible, though it depends on the wishes of the original authors. Stockfish Chess [1] is the one GPL v3 licensed app that I know of which has been available for... quite some time, now. I've seen several other Chess apps build on that engine, which go as far back as when I was just starting iOS development. Now, VLC was the one case where one volunteer for the project invoked the GPL to get Apple to take an iOS port of the app off the store [2]. Based on that situation, it seems that if the original authors of a GPL licensed codebase want to pursue a claim against an app that uses that code, they can, and Apple will take it seriously. I don't believe that situation has changed. EDIT: For your own sake, it's probably best if you approach the original author to see if they can make an exemption, in writing, for the DRM situation. IANAL, but that seems like it would be the cleanest way to go about handling GPL licensed code without issue. [1] - http://stockfishchess.org [2] - http://www.tuaw.com/2011/01/08/vlc-app-removed-from-app-store/

Indeed, even in "classical chess engines" like Stockfish which previously required handcrafted heuristics at leaf nodes, in recent years the NNUE [1] [2] has greatly outperformed it. Note that this is a completely different approach from the one that AlphaZero takes, and modern Stockfish is significantly stronger than AlphaZero. [1] https://stockfishchess.org/blog/2020/introducing-nnue-evaluation/ [2] https://www.chessprogramming.org/Stockfish_NNUE

Hey, I have my own chess TUI which allows you to play against several beginner-level chess AI opponents: - Maia chess (https://maiachess.com), the human-like chess engine based on neural networks, - several of neural networks by Dietrich Kappe (https://github.com/dkappe/leela-chess-weights/releases), - and handicapped Stockfish (https://stockfishchess.org). The whole thing is at https://github.com/magv/bchess, and can be installed with just 'pip install bchess'.

First time they mention it is page 10: > one of the strongest and most widely-used programs is Stockfish [81]. Here's the citation, note the date: > [81] The Stockfish Development Team. Stockfish: Open source chess engine, 2021. https://stockfishchess.org/. They mention the version number only once, further down, and don't point out that it's out of date since February 2018. All other 11 mentions of it don't have the version number, like in that sentence: > In Chess, PoG(60000,10) is stronger than Stockfish using 4 threads and one second of search time.

Stockfish is free and open source. https://stockfishchess.org/

My casual gaming consists in ~10 mins trying to beat Stockfish (https://stockfishchess.org/). App with no ads, no distractions, open-source, recreative and good mental exercise.

Stockfish 5 was released yesterday: http://stockfishchess.org/ As mentioned elsewhere in this thread, Stockfish is just an engine - you must install a GUI separately. XBoard is well known, but there are better alternatives: http://chessx.sourceforge.net/ http://scidvspc.sourceforge.net/

Yes there is also another factor in a chess position which is not included in this encoding which is who is next to move. That being said the basic idea is really interesting. I'd love to see a fully opensource competitor to chessbase. For people who don't know, chessbase is a subscription service which gives you a windows-only chess analysis platform and game database. It allows you to do advanced searches (eg I want to find games by 2500+ rated players in the Caro-Kann where black has a pawn on c5 and a bishop on e7 or whatever) which advanced players use to do "prep" (deep positional analysis typically of opening positions) which they save in reams of files prior to memorization. It's probably not an exaggeration to say nearly all strong players and serious improvers subscribe to it. Chessbase made themselves persona non grata in the opensource world by apparently ripping off parts of stockfish and selling it under the names "Fat Fritz" and "Houdini"[1] and even were that not the case it would be great to have mac and linux opensource options. [1] https://stockfishchess.org/blog/2022/public-court-hearing-soon/

I think when looking at least at large scale applications in the context of games (and not just super-expensive showcases), like in the Stockfish chess engine, we see that it's not primarily about depth, it's about architecture design. Reference: start here https://stockfishchess.org/blog/2021/stockfish-14/ and go down the rabbit hole... In the broadly useful domain of recommender systems (which typically make use of some type of RL-like feedback loop, but can be implemented using simple clustering approaches), at least in 2019, neural network-based approaches didn't seem to fair too well, either: https://arxiv.org/pdf/1907.06902.pdf (arXiv pre-print, but this is an award-winning paper). Since then, it seems that researchers are moving away from getting deeper and deeper (the low-hanging fruit), and try to be more creative instead: new architectures, combining symbolic (logic-based) and sub-symbolic (ML-based) AI, etc.

This is a slight tangent to the article, but in the hope HN readers will find this as fascinating as I have recently... There's a three-way battle developing between AlphaZero (as described in the article, courtesy of DeepMind), LCZero[5] (derived from LeelaZero[1] -- an open source interpretation of the same principles as AZ), and Stockfish[2] (a long-standing open source chess engine that has recently begun including neural network support). The 'Top Chess Engine Championship'[3] seems to be a good way to follow the latest news; they also stream matches live on their website[4] (it is quite an information-dense site). You can play against an up-to-date implementation of Stockfish in your browser -- no registration or signup required -- at https://lichess.org [1] - https://zero.sjeng.org/ [2] - https://stockfishchess.org/ [3] - https://en.wikipedia.org/wiki/Top_Chess_Engine_Championship [4] - https://tcec-chess.com/ [5] - https://www.lczero.org/ Edit: correct LeelaZero -> LCZero

We saw this in Chess engines about 20 years back (when they started getting seriously strong) they play Chess incredibly well but looks very little like what a human playing does. It was fascinating to watch the changes in chess theory through that period as the machines validated or invalidated concepts and ideas that GM's had posited but been unable to prove one way or the other. John Speelman wrote an intro to The Mammoth Book of Chess (that thing was awesome,I think I wore out three copies) which (paraphrasing horribly) that Chess is a realm of pure thought and that computers play it the way an alien might. The best engines on commodity hardware now require offering pawn odds for a top human to even have a chance and their strength is accelerating[1] (stockfish now has a distributed test architecture to test for regressions which is incredibly cool[2]) [1] http://www.chess.com/article/view/how-rybka-and-i-tried-to-beat-the-st… (Rybka was/is one of the strongest engines and in concert with a human it still couldn't beat Stockfish). [2] https://stockfishchess.org/get-involved/

You'll notice I didn't mention copyright, and that's because I don't think it's relevant. I think your analysis is correct. Keep in mind too that Stockfish – the engine I work on, although I wasn't at the time – was the subject of a high-profile defense of the GPL in Germany: https://stockfishchess.org/blog/2021/our-lawsuit-against-chessbase/. That case was different as it involved wholesale copying of the source code, rather than porting ideas. Ideas shouldn't be copyrightable. But copyright and plagiarism are orthogonal, and questions of morality are much more tied to the latter. It would be illegal (in the United States) for me to publish a copy of Nineteen Eighty-Four, but not immoral. It was not immoral, in my view, for Aaron Swartz to try to liberate JSTor articles. That doesn't make plagiarism acceptable, either. And therefore, I'm willing to call it out when I see it.

Something similar happened recently with Stockfish and ChessBase. They reached an agreement that ChessBase will no longer sell their product without complying with GPL but they aren't forced to distribute the source if they decide to stop selling. https://stockfishchess.org/blog/2022/chessbase-stockfish-agreement/

The current versions of Stockfish (designated NNUE) are definitely AZ influenced. In fact it was implemented in collaboration with the LCZero devs. https://stockfishchess.org/blog/2020/introducing-nnue-evaluation/

Last year Stockfish attempted to enforce the GPLv3 version of the clause against ChessBase. I'm not sure how it has turned out so far. https://stockfishchess.org/blog/2021/our-lawsuit-against-chessbase/ Previous discussion: https://news.ycombinator.com/item?id=27896386

> IBM managed to beat Garry Kasperov using symbolic AI did they not? So in what way does it not work? Ok, I should be clearer. ML approaches are way way better than symbolic approaches. Given almost any problem, it is much much easier to make an ML approach work than any symbolic approach. Yes, chess was first solved symbolically, but it's since been solved by ML better and more easily, to the point that stockfish now incorporates neural nets [1]. ML has also given extremely high levels of performance on Go, Starcraft, DoTA, and on protein folding, image recognition, text processing, speech recognition, and pretty much everything else. I would challenge you to name any (non-simple) problem where traditional AI methods are still state of the art. [1] https://stockfishchess.org/blog/2020/stockfish-12/

And I might be the only idiot here, but I tried to run stockfish from source and it was not an instant process. In addition, there isn't really a front end, you essentially end up with a CLI to input moves. And for those who say, hey you, there are prebuilt binaries, just download them! Check out this message [1] " The binaries at the top of the table are fastest, but may not support all CPUs. If you don't know which CPU you have, you can go down the list and pick the first binary that does not crash. " Yeah okay, a pragmatic set of instructions that can't fail... From this I think we could see why a product built on top of stockfish might make sense, even if the linked product might not do as such. [1]https://stockfishchess.org/download/

To elaborate, in the Top Chess Engine Championship (which is also used as a benchmark in the AlphaZero vs Stockfish comparison) Stockfish has won all seasons since May 2020[1,2]. A common runner up for those seasons is LCZero[3], which is an engine that is derived from/a reimplementation of AlphaZero. Stockfish is also ahead of LCZero in Fischer random chess (as hosted at TCEC) winning 4 out of the 5 FRC tournaments. As for how close Stockfish 8 is to a current version of Stockfish, Stockfish 15 has ~400 more ELO than Stockfish 8 as measured in their own self-tests[4]. However, when making these comparisons between AlphaZero and Stockfish it might be tempting to frame it as machine-learning-engine vs classical-engine, which is not true. Stockfish incorporates a neural network when evaluating chess positions[5]. [1]: https://en.wikipedia.org/wiki/Top_Chess_Engine_Championship#Tournament… [2]: https://en.wikipedia.org/wiki/Stockfish_(chess)#Top_Chess_Engine_Champ… [3]: https://en.wikipedia.org/wiki/Leela_Chess_Zero [4]: https://github.com/glinscott/fishtest/wiki/Regression-Tests#fishtest-p… [5]: https://stockfishchess.org/blog/2020/introducing-nnue-evaluation/

I'm not a lawyer, nor am I very familiar with contract law, so take this with a grain of salt. I think technically yes, practically it is a separate up hill battle. Monetary damages have to be not-speculative, something like "because of defendant not complying with the contract I ended up spending <this> money on <these> software licenses" would probably work, but something like "because of defendant not complying with the contract I ended up making an inferior product (since I had to rewrite this code from scratch)" probably wouldn't. I doubt that leaves many big lawsuits, it's hard to think of concrete damages that result from people improperly modifying and distributing linux (unfortunately common). Maybe customers of ChessBase who purchased Fat Fritz 2 or Houdini 6 (context: [1]) would have a claim for the return of their license fees, since if ChessBase was properly distributing it as GPL software they almost certainly would have been able to acquire it for free - that's like $50/person though - not a huge money maker. [1] https://stockfishchess.org/blog/2021/our-lawsuit-against-chessbase/

> 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. 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…

I've read through this thread and I haven't seen a simple summary of the situation as it stands with respect to copying and the GPL violation. Here's what I believe to have happened: 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". [1] 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. [1] 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…

Surprisingly, I find myself slightly skeptical of Stockfish's claims, which is... a disquieting feeling. Could someone help me out by finding the flaw in my logic? 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-2/). 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-your-note… 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…