> Many commenters are missing that the issue is not that an Open Source project was repackaged as a commercial project, but that the open source origin has bee

> Many commenters are missing that the issue is not that an Open Source project was repackaged as a commercial project, but that the open source origin has been hidden. That is not what Joost VandeVondele, current maintainer of the Stockfish project, posts: > 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 > 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. https://blog.stockfishchess.org/post/643239805544792064/statement-on-fat-fritz-2 https://blog.stockfishchess.org/post/643239805544792064/stat...