Leorik - UCI chess engine
Author-Thomas Jahn Rating CEDR=2392
v.2.1
This version adds a pawn structure term to the evaluation: A dynamic bonus is awarded to passed pawns based on the phase of the game and their position on the board. Pawns being connected with or protected by other friendly pawns are also awarded a constant bonus. Isolated pawns receive a constant malus. The pawn structure term is only updated when a pawn moves or get's captured. A small and simple pawn hash table is used to avoid re-evaluating previously encountered pawn structures. With as little as 4999 slots a hit-rate of >90% is achieved and so the overall performance cost of adding this term is small. Leorik 2.1 is only a few percent slower than the previous version and gains about 50 Elo in strength.
Features
Bitboards and Copy/Make
Pseudo-legal move generator
Evaluation based exclusively on tapered, tuned PSTs
Incremental updates of the evaluation and Zobrist hash
Two-bucket Transposition Table.
Staged move generation
MVV-LVA sorted captures
Killers
PVS search
Quiescence search
Individual statistics: Leorik 1.0 - 140 games (+ 34,= 6,-100), 26.4 %
Komodo 12.1.1 : 2 (+ 0,= 0,- 2), 0.0 %
Jackychess 0.9.14 : 1 (+ 0,= 0,- 1), 0.0 %
Fire 8 NN MC.3 : 4 (+ 1,= 0,- 3), 25.0 %
Loki 3.5.0 : 2 (+ 0,= 0,- 2), 0.0 %
MadChess 3.0 : 2 (+ 0,= 0,- 2), 0.0 %
DanaSah 9.0 : 2 (+ 0,= 0,- 2), 0.0 %
Cosette 5.1 : 2 (+ 0,= 1,- 1), 25.0 %
Kouri 1.15 : 1 (+ 1,= 0,- 0), 100.0 %
Sapeli 2.0 : 1 (+ 0,= 1,- 0), 50.0 %
Rustic Alpha 3.0.0 : 1 (+ 1,= 0,- 0), 100.0 %
Iathena 2020-12-19 : 1 (+ 1,= 0,- 0), 100.0 %
FracTal 1.0 : 1 (+ 1,= 0,- 0), 100.0 %
Chareth 0.1.0 : 1 (+ 1,= 0,- 0), 100.0 %
Quokka 2.1 : 1 (+ 1,= 0,- 0), 100.0 %
Monochrome r203 : 1 (+ 1,= 0,- 0), 100.0 %
Colossus 2021b : 2 (+ 0,= 0,- 2), 0.0 %
Stockfish 14.1 : 4 (+ 0,= 0,- 4), 0.0 %
Pulse 1.7.3 : 1 (+ 1,= 0,- 0), 100.0 %
Coiled 1.1 : 2 (+ 0,= 0,- 2), 0.0 %
Igel 3.0.10 : 2 (+ 0,= 0,- 2), 0.0 %
Fisherov 0.98i : 2 (+ 1,= 0,- 1), 50.0 %
BLANK 1.3.0 : 1 (+ 1,= 0,- 0), 100.0 %
Lynx 0.9.0 : 1 (+ 1,= 0,- 0), 100.0 %
Fisherov 0.98j : 6 (+ 1,= 0,- 5), 16.7 %
Kayra 1.1 : 2 (+ 1,= 0,- 1), 50.0 %
MisterQueen : 1 (+ 1,= 0,- 0), 100.0 %
Fritz 15 : 6 (+ 0,= 0,- 6), 0.0 %
Weiawaga 4.0 : 1 (+ 0,= 0,- 1), 0.0 %
Devel 4.0.2.3 : 4 (+ 0,= 0,- 4), 0.0 %
Popochin 4.3 : 1 (+ 0,= 0,- 1), 0.0 %
Prophet 4.1 : 1 (+ 0,= 0,- 1), 0.0 %
Bagatur 3.2 : 2 (+ 1,= 0,- 1), 50.0 %
Cheese 3.0.1 : 2 (+ 0,= 0,- 2), 0.0 %
Combusken 2.0.0 : 2 (+ 0,= 0,- 2), 0.0 %
Stockfish 170122 : 2 (+ 1,= 0,- 1), 50.0 %
Clover 3.0 : 2 (+ 0,= 0,- 2), 0.0 %
Anka 0.6.3 : 5 (+ 0,= 0,- 5), 0.0 %
Belofte 2.1.5 : 2 (+ 2,= 0,- 0), 100.0 %
CorChess 070222 : 2 (+ 1,= 0,- 1), 50.0 %
Dragon 2.6.1 : 2 (+ 1,= 0,- 1), 50.0 %
ClassicAra 0.9.9 : 1 (+ 0,= 0,- 1), 0.0 %
Mayhem 6.7 : 2 (+ 2,= 0,- 0), 100.0 %
Stockfish 170222 : 4 (+ 0,= 0,- 4), 0.0 %
Keele 1.0 : 6 (+ 1,= 0,- 5), 16.7 %
Fire 8.2 : 4 (+ 2,= 0,- 2), 50.0 %
Fatalii 0.1.0 : 3 (+ 3,= 0,- 0), 100.0 %
Tantabus 2.0.0 : 3 (+ 0,= 0,- 3), 0.0 %
Journeyman 1.0 : 3 (+ 1,= 1,- 1), 50.0 %
Admete 1.4.0 : 2 (+ 0,= 0,- 2), 0.0 %
Eggnog 3.0 : 1 (+ 0,= 1,- 0), 50.0 %
Expositor 2WQ23 : 1 (+ 0,= 0,- 1), 0.0 %
Dumb 1.9 : 2 (+ 0,= 0,- 2), 0.0 %
Lozza 2.2 : 1 (+ 0,= 0,- 1), 0.0 %
BrainLearn 16.1 : 2 (+ 0,= 0,- 2), 0.0 %
Stockfish 080322 : 2 (+ 0,= 0,- 2), 0.0 %
ShashChess 21.1 : 2 (+ 0,= 0,- 2), 0.0 %
Little Goliath 3.15.4 : 3 (+ 0,= 0,- 3), 0.0 %
Frozenight 1.0.1 : 2 (+ 0,= 0,- 2), 0.0 %
Arasan 23.3 : 2 (+ 0,= 0,- 2), 0.0 %
Frozenight 2.0.0 : 1 (+ 0,= 0,- 1), 0.0 %
Koivisto 8.1 Ipman : 2 (+ 0,= 0,- 2), 0.0 %
Princhess 0.7.0 : 3 (+ 1,= 2,- 0), 66.7 %
Walleye 1.6.0 : 3 (+ 3,= 0,- 0), 100.0 %
Kayra 1.2 : 2 (+ 0,= 0,- 2), 0.0 %
Stockfish 250322 : 2 (+ 0,= 0,- 2), 0.0 %
Leorik 2.1 download from page
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