Stockfish 15.1 is here
With this release, version 5 of the NNUE neural net architecture has been introduced, and the training data has been extended to include Fischer random chess (FRC) positions. As a result, Elo gains are largest for FRC, reaching up to 50 Elo for doubly randomized FRC (DFRC). More importantly, also for standard chess this release progressed and will win two times more game pairs than it loses against Stockfish 15. Stockfish continues to win in a dominating way all chess engine tournaments, including the TCEC Superfinal, Cup, FRC, DFRC, and Swiss as well as the CCC Bullet, Blitz, and Rapid events.
Evaluation Updates
This release also introduces a new convention for the evaluation that is reported by search. An evaluation of +1 is now no longer tied to the value of one pawn, but to the likelihood of winning the game. With a +1 evaluation, Stockfish has now a 50% chance of winning the game against an equally strong opponent. This convention scales down evaluations a bit compared to Stockfish 15 and allows for consistent evaluations in the future.
