Updated: May 11
Another update to the Rebel chess engine in very short order, which according to the author should result in a strength increase of about 100 Elo points.
Here is what the author Mr. Ed Schröder wrote an his website about the latest release of the Rebel engine:
"1. New and stronger neural network made from 1.87 billion positions.
2. Estimated strength increase over Rebel 14.2 emulating CCRL 40/2 testing in the range of 80-130 elo.
3. See the Rebel 15 development diary for details.
4. NNUE tuner parameter in Engine Settings. Default setting now 70%.
5. For the moment Rebel 15 is only available as AVX2 engine. It has to be seen if we are still able to provide a weaker SSE version for older computers. NNUE evaluation strongly relies on the AVX2 instruction set and there might come a moment older computers become an obstacle to progress."
It is a pity that only one version of the Rebel 15 chess engine has been made available to run and only on modern processors and only on Windows. No compilation for older and still popular processors; no compilation for other operating systems like Linux or macOS. No support for Syzygy tablebases.
That's a lot of "lack."
Maybe it would be better to release this excellent chess engine a bit less frequently, but more refined ?
We get the fifteenth version of the chess engine, a large and round number indicating an important update and apart from the claims of increased power, the Rebel 15 chess engine is, to put it mildly, simply unpolished.