Fat Fratz 2.0 Copyleft Infringement

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Bernt Nicht

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Feb 10, 2021, 7:12:28 AMFeb 10
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Hello Community,

I just read a post (https://de.chessbase.com/post/fat-fritz-2-0-die-neue-nummer-1) for Fat Fritz 2.0 saying it is based on Stockfish with other NNUE network, isn't this an infringement of the copyleft licence of Stockfish to sell it commercially?

Bernt Nicht

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Feb 10, 2021, 7:13:41 AMFeb 10
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Quote: "Fat Fritz 2.0 basiert auf der Engine Stockfish 12, verwendet aber ein völlig neues neuronales Netzwerk mit besseren Bewertungen und größerem Leistungsumfang."

Translated: "Fat Fritz 2.0 is based on the engine Stockfish 12, but uses a completely new neural network with improved evaluations and greater performance."

Fabian Fichter

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Feb 10, 2021, 3:31:20 PMFeb 10
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While selling a -50 Elo "improvement" of an open-source engine for 99€ of course is morally very questionable, I do not think it is illegal. Their code is public on github, so they adhere to the copyleft there. The only thing that would be problematic is if they include the net in the binary (I don't know if they do), because then one could argue that the net also falls under the copyleft and has to be under GPL, but I am not entirely sure. If they distribute the net separately from the binary, I think it is legal.

Joost VandeVondele

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Feb 10, 2021, 3:45:19 PMFeb 10
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their distributed binary includes the net, and they thus infringe on our licensing terms as they do not provide the necessary information to recreate the binary with identical functionality. Other aspects of the license are violated as well. We are planning our further steps, which we will not discuss on the mailing list. If you are a lawyer, and interested to help out in this case, you can contact me directly.

Fabian Fichter

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Feb 10, 2021, 3:59:59 PMFeb 10
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Wow, I did not know this, then it is not only immoral but also stupid. No, I am not a lawyer, but according to my amateurish legal understanding your reasoning seems correct, the GPL is pretty clear in that regard. Good to know that you are already looking into it, that's all the community needs to know.

Joachim Müller (JojoM)

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Feb 11, 2021, 3:38:48 AMFeb 11
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I'll be willing to share the cost should it be necessary to cover the legal expenses.

Graci Henn

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Feb 11, 2021, 4:27:48 AMFeb 11
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They should have separated the net from the engine so it can be tested with public stockfish and see if it is really better.

Daniel Tran

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Feb 12, 2021, 4:06:35 PMFeb 12
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These chessbase people are degusting. Preying on the uninformed to make some quick cash.

Joost VandeVondele

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Feb 15, 2021, 10:03:14 PMFeb 15
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Feel free to share our statement on Fat Fritz 2.


distributing this on social media is welcome

ani19bd

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Feb 16, 2021, 1:42:39 AMFeb 16
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CCRL seem to update their Fat Fritz 2 description to " Fat Fritz 2 is an NNUE network trained and developed by Chessbase, running in a modified version of a Stockfish binary. " I'm a admin of a Facebook chess group that has 67k members, going to share the SF statement @ Joost VandeVondele. 

Leonardo Ljubičić aka Dragon Mist

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Feb 16, 2021, 11:06:22 AMFeb 16
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Retweeted left and right.

Otomar Thoma

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Feb 16, 2021, 5:00:55 PMFeb 16
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Hello , quick reaction is to release SF13

Dne úterý 16. února 2021 v 17:06:22 UTC+1 uživatel Leonardo Ljubičić aka Dragon Mist napsal:

ani19bd

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Feb 17, 2021, 1:11:46 AMFeb 17
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Here is interview by ChessBase India of Albert Silver : https://www.youtube.com/watch?v=CvYwTuXnoCw

Joachim Müller (JojoM)

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Feb 17, 2021, 2:47:17 AMFeb 17
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I'll also do my best.

Gosse

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Feb 17, 2021, 4:51:06 AMFeb 17
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Statement on Fat Fritz 2

Stockfish is an open-source project, sharing and freely distributing the code, tools and data needed to deliver this chess engine. We do this because we are convinced that open software and open data are key ingredients to make rapid progress, and thus for the benefit of our users. The recent progress in playing strength of Stockfish confirms the path taken. We proudly provide the tools for free chess analysis to millions of users, with countless titled players using Stockfish for their preparation. Be assured that free engines will serve you well!

Recently, ChessBase has started distribution and sales of the Fat Fritz 2 chess engine. This chess engine is a Stockfish derivative, with a few lines of code modification (engine name, authors list and a few parameters), and a new set of NNUE net weights considered proprietary. ChessBase’s communication on Fat Fritz 2, claiming originality where there is none, has shocked our community. Furthermore, the engine Fat Fritz 2 fails to convince on independent rating lists, casting doubt on the usefulness of those modifications. Indeed, we feel that customers buying Fat Fritz 2 get very little added value for money. Claims to the contrary appear misleading.

Selling Stockfish derivatives is possible with the GPLv3 license we grant, but not without requirements. 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.

—Joost VandeVondele, current maintainer of the Stockfish project

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