Leorik - UCI chess engine
Author-Thomas Jahn Rating CEDR=2771
v.2.4
This version keeps the evaluation of version 2.3 but features an improved the search.
The most notable addition is the use of a Static-Exchange-Evaluation (SEE) to skip bad captures in Quiescence search and to search moves with a bad SEE score at a reduced depth in the main search. This new version also includes a nice simplification: I removed Futility Pruning and made Null-Move Pruning the only remaining place where entire branches can be pruned because they are just 'too good' for one side. Futility pruning relied on the static evaluation of a position and didn't explore it further if this evaluation was way below alpha. I now use the same idea in my null-move pruning implementation: When a position's static evaluation is way above beta and close to the leaves then Leorik just returns beta without further evaluation.
Last but not least Leorik now recognizes certain drawn positions with a material advantage for one side (e.g. KvKNN) and evaluates them much closer to zero.
The playing strength of Version 2.4 should be around 2800 Elo.
Individual statistics: Leorik 2.1 - 216 games CEDR (+ 59,= 13,-144), 30.3 %
Critter 1.6a : 2 (+ 0,= 0,- 2), 0.0 %
Houdini 1.5a : 2 (+ 0,= 0,- 2), 0.0 %
Kouri 1.15 : 1 (+ 1,= 0,- 0), 100.0 %
Stockfish 15 : 2 (+ 0,= 0,- 2), 0.0 %
Lc0 0.29.0-rc0 : 2 (+ 0,= 0,- 2), 0.0 %
Walleye 1.6.0 : 1 (+ 1,= 0,- 0), 100.0 %
Frozenight 3.0.1 : 1 (+ 0,= 0,- 1), 0.0 %
GOOB 1.0 : 1 (+ 1,= 0,- 0), 100.0 %
Pigeon 1.5.1 fix : 3 (+ 3,= 0,- 0), 100.0 %
Inanis 1.0.1 : 1 (+ 0,= 0,- 1), 0.0 %
Lozza 2.2 : 2 (+ 1,= 0,- 1), 50.0 %
Wasp 5.50 : 4 (+ 0,= 0,- 4), 0.0 %
Komodo 13.02 : 2 (+ 0,= 0,- 2), 0.0 %
Hiarcs 15.5 : 2 (+ 0,= 0,- 2), 0.0 %
Caligula 1.0b : 9 (+ 1,= 1,- 7), 16.7 %
Lynx 0.10.0 : 4 (+ 4,= 0,- 0), 100.0 %
K2 0.99 : 2 (+ 1,= 0,- 1), 50.0 %
Rodent NNUE 1.0 : 2 (+ 0,= 0,- 2), 0.0 %
Stash 33.0 : 4 (+ 0,= 0,- 4), 0.0 %
Tinman 0.41 dev : 1 (+ 1,= 0,- 0), 100.0 %
RofChade 3.0 : 2 (+ 0,= 1,- 1), 25.0 %
Rebel 15x2 : 6 (+ 0,= 0,- 6), 0.0 %
Neuromancer 1.2 : 1 (+ 1,= 0,- 0), 100.0 %
StockfishMZ 170522 : 2 (+ 0,= 0,- 2), 0.0 %
Coiled 1.1 : 2 (+ 0,= 0,- 2), 0.0 %
Colossus 2022a : 7 (+ 3,= 0,- 4), 42.9 %
Smallbrain 1.2 : 2 (+ 2,= 0,- 0), 100.0 %
CorChess 290522 : 4 (+ 0,= 0,- 4), 0.0 %
Fisherov chess monk 1.1 : 6 (+ 0,= 0,- 6), 0.0 %
Bagatur 3.3 : 14 (+ 0,= 5,- 9), 17.9 %
Stockfish 290522 Ivec : 2 (+ 0,= 0,- 2), 0.0 %
Eggnog 3.0 : 3 (+ 1,= 0,- 2), 33.3 %
Vafra 3.3.2 : 6 (+ 0,= 0,- 6), 0.0 %
Uralochka 3.35a : 2 (+ 0,= 0,- 2), 0.0 %
Stockfish 290522 : 6 (+ 0,= 0,- 6), 0.0 %
Journeyman 1.4 : 2 (+ 1,= 0,- 1), 50.0 %
Berserk 9-dev3 : 6 (+ 0,= 0,- 6), 0.0 %
Koivisto 8.9 : 4 (+ 0,= 0,- 4), 0.0 %
Fisherov chess monk : 2 (+ 0,= 0,- 2), 0.0 %
Fritz 15 : 2 (+ 0,= 0,- 2), 0.0 %
Igel 3.1.0 : 12 (+ 0,= 0,- 12), 0.0 %
Counter 4.1 : 12 (+ 0,= 0,- 12), 0.0 %
Journeyman 1.7 : 10 (+ 8,= 0,- 2), 80.0 %
Mayhem 7.3 : 10 (+ 4,= 2,- 4), 50.0 %
Horowitz 2.2 : 11 (+ 10,= 1,- 0), 95.5 %
Uralochka 3.36c : 5 (+ 0,= 0,- 5), 0.0 %
Combusken 2.0.0 : 2 (+ 0,= 0,- 2), 0.0 %
MrBob 1.1.0 : 2 (+ 0,= 1,- 1), 25.0 %
Eubos 2.12 : 1 (+ 1,= 0,- 0), 100.0 %
Journeyman 2.1 : 1 (+ 0,= 0,- 1), 0.0 %
Anka 0.6.3 : 3 (+ 2,= 1,- 0), 83.3 %
Francesca 0.31a : 2 (+ 0,= 0,- 2), 0.0 %
Gargantua 1.0 : 1 (+ 1,= 0,- 0), 100.0 %
Smallbrain 4.0 : 1 (+ 0,= 0,- 1), 0.0 %
Jackychess 0.12.0 : 1 (+ 1,= 0,- 0), 100.0 %
MisterQueen : 1 (+ 1,= 0,- 0), 100.0 %
Weiawaga 5.0 : 1 (+ 0,= 0,- 1), 0.0 %
BLANK 1.3.0 : 1 (+ 1,= 0,- 0), 100.0 %
Avalanche 1.0.0 : 1 (+ 1,= 0,- 0), 100.0 %
Popochin 4.3 : 1 (+ 1,= 0,- 0), 100.0 %
Monochrome r203 : 1 (+ 1,= 0,- 0), 100.0 %
Tantabus 2.0.0 : 1 (+ 0,= 1,- 0), 50.0 %
Rustic-alpha 3.0.0 : 1 (+ 1,= 0,- 0), 100.0 %
Sapeli 2.0 : 1 (+ 1,= 0,- 0), 100.0 %
Prophet 4.2 : 1 (+ 0,= 0,- 1), 0.0 %
Princhess 0.7.0 : 1 (+ 1,= 0,- 0), 100.0 %
ChessMatrix 1.0.6 : 1 (+ 1,= 0,- 0), 100.0 %
Claudia 0.51 : 1 (+ 1,= 0,- 0), 100.0 %
github:https://github.com/lithander/Leorik/releases/tag/2.4
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