A while ago, we released Koivisto v3.0 after a significant improvement in strength. It's time for another release again
We'd like to thank Andrew Grant for the OpenBench framework (and putting up with our questions about it!), without which we wouldn't be able to test so many new ideas; it has greatly improved our experimentation process since we started using it around Koivisto v2.0.
We'd also like to thank noobpwnftw for significant help with testing.
Our latest regression test shows significant Elo gain over Koivisto v3.0:
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60+0.6:
ELO | 141.20 +- 18.81 (95%)
SPRT | 60.0+0.6s Threads=1 Hash=64MB
LLR | 0.00 (-2.94, 2.94) [0.00, 0.00]
Games | N: 960 W: 501 L: 131 D: 328
15+0.1:
ELO | 120.88 +- 13.38 (95%)
SPRT | 15.0+0.15s Threads=1 Hash=16MB
LLR | 0.00 (-2.94, 2.94) [0.00, 0.00]
Games | N: 1952 W: 1002 L: 349 D: 601
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40/15:
ELO | 84.12 +- 20.83 (95%)
SPRT | 40/15s Threads=1 Hash=16MB
LLR | 3.11 (-2.94, 2.94) [0.00, 5.00]
Games | N: 640 W: 260 L: 108 D: 272
Changes:
- updated tt-usage.
- does forced moves immediately.
- added bishop pawn endgame relations evaluation term.
- retuned entire evaluation with a larger dataset.
-> tuned mobility scores instead of computing them.
-> tuned king safety scores instead of computing them.
- cleaned up the code and added comments.
- asymmetric piece square tables based on king-king relation.
- changed reduction/extension policy.
- improved general time management.
- fixed cyclic time management which leads to the engine using a lot more time in games with cyclic time controls.
- fixed speed-related issues.
- added a logo and banner.
The Koivisto engine authors, Kim, Finn and Eugenio.