The German chess software program firm ChessBase and the crew behind the open-source chess engine Stockfish have reached a settlement and ended their authorized dispute over the latter’s declare concerning a repeated license violation by Chessbase with their merchandise Fats Fritz 2 and Houdini 6.
The settlement between Chessbase and Stockfish was introduced on the Stockfish web site on Saturday and confirmed as correct to Chess.com by Matthias Wullenweber, proprietor and chief programmer of Chessbase.
The 2 events concerned within the litigation, which appeared earlier than the District Court docket in Munich, Germany, have agreed that Chessbase, longterm, can proceed distributing merchandise so long as the corporate ensures compliance with the GPL-3.0 license phrases and adequately informs the general public about using the Stockfish software program in its merchandise.
The phrases of the settlement embrace that Chessbase refrains from distributing and/or making publicly obtainable the Stockfish software program for a interval of 1 yr. After one yr, Chessbase can train the license to the Stockfish software program once more, underneath the situations of the GPL-3.0. In case the phrases are breached, Chessbase must pay an applicable quantity to the Free Software program Basis Europe eV
For the aim of informing the general public, Chessbase will place a clearly seen discover on all of its web sites regarding Fats Fritz 2 and/or Houdini 6, containing a textual content referring to the GPL-3.0 license phrases and the settlement. Additionally, they may internally introduce the function of a “Free Software program Compliance Officer” and record underneath the area foss.chessbase.com the merchandise that comprise the software program Stockfish underneath the GPL-3.0 or different Free and Open Supply Software program (FOSS). If the respective licenses require the supply of the supply code, Chessbase will allow a obtain of the supply code by anybody from there.
In case Chessbase will proceed distributing merchandise based mostly on Stockfish after one yr, their ads must confer with using Stockfish, and comparisons of enjoying energy with Stockfish or different chess engines shall be truthful and provable (eg by reference to applicable present rankings ) and shall confer with present variations.
Additionally, neural networks supplied by Chessbase to be used with Stockfish which can be included within the compilation or dynamically loaded at runtime to initialize the info buildings and logic of the software program have to be topic to GPL-3.0 or a suitable license.
In July 2021, the crew behind Stockfish sued Chessbase for promoting merchandise based mostly on Stockfish, an open-source chess engine, with out attaching the license textual content and/or making obtainable the entire corresponding supply code. Because the copyright homeowners, main builders of Stockfish had terminated the GPL license, and wWith out a license, Chessbase infringed copyright by persevering with to distribute the merchandise—therefore the lawsuit.
Earlier that yr, the groups behind Stockfish and one other open-source chess program, Leela Chess Zero, had claimed that the engine in Fats Fritz 2 is Stockfish with minimal modifications, that Fats Fritz 2 violated the GNU Basic Public License underneath which Stockfish was launched. , and that Chessbase’s advertising has made false claims about Fats Fritz 2’s enjoying energy.
In a public listening to on July 4, 2022, in Munich, the choose confirmed that it was certainly potential for the Stockfish crew to terminate the GPL license. As German legislation stipulates, the choose nonetheless requested the 2 events to try to work on a settlement. If they’d failed to return to an settlement, a brand new court docket session was scheduled for March 2023.
Joost VandeVondele, the present maintainer of Stockfish, wrote that the settlement “strengthens the Stockfish venture in its intention to ship the world’s primary chess engine as a Free Software program and that enables ChessBase to distribute our software program sooner or later.” He defined the explanation for re-instating the license a yr from now as follows:
“We really feel that that is within the spirit of Free Software program and to the good thing about the group. ChessBase has now acknowledged the worth and potential of open supply software program, and Stockfish specifically, and made a transparent dedication to respecting the Free Software program ideas. “