There was a comment addressing that yesterday https://news.ycombinator.com/item?id=27901876
The form matters.
I don't know; I want to agree, but this is fraught with peril.
If they don’t use pickle, they shouldn’t release in pickle format. They should release in a format such that you can take the source they release and use the model weights as required “installation information” and run the software. Probably the native format for the app.
We don’t know if they do or they don’t. That would be a matter to be decided in the court. Likewise you might argue the weights are not installation information in the GPL sense. Stock fish asserts they don’t release weights. Chess base hasn’t commented. I can’t find them.
Simply stating “the software runs! The weights must already be distributed” isn’t correct in the sense that the GPL demands. By analogy, “the software runs the source must already be distributed” isn’t correct in the same way.
I looked I don’t even see where they are releasing the code. Is it this? https://github.com/DanielUranga/Stockfish
While such questions seem reasonable the first time you encounter them, they have been thoroughly answered for similar things: For example, for source code, releasing the code handwritten on toilet paper is not a "preferred form of modification" (as the GPL requires). A public web site with ASCII code is. In the past, a CD shipped by post also was, but I don't know if the situation there is changing.
So, for the weights of a deep network, it's pretty clear that any reasonably documented format for loading the weights into memory would do. That could be one of the well-established matrix/tensor blob formats, or a pickle file, or HDF5, or whatever. Nobody thinks that Stockfish would fight them over the exact format chosen.
As for the training parameters etc., and the questions you get into there, those seem indeed to be open questions when it comes to FOSS and deep learning. Debian has started taking its first steps in thinking about how this all relates to the Debian Free Software Guidelines, for example: https://salsa.debian.org/deeplearning-team/ml-policy
> I don't know; I want to agree, but this is fraught with peril.
Yes, the legal world often is. It's full of words like "reasonable", "expectation", "preferred", etc. But I think you're overcomplicating the matter. There is definitely a gray zone here, but ChessBase GmbH are not in that gray zone, they're clearly far into the wrong.