A UCI compatible chess engine written in Rust.
Chess-RS 0.6.0 what's new?
Additions
Add null-move pruning: if the side to move skips their turn (makes a "null move") and the opponent still can't do anything dangerous, the current position is probably strong enough that there's no point searching further — we can prune this subtree since under best play the opponent wouldn't have allowed it anyway.
Enhancements
Implement fancy magic bitboards for faster sliding piece attack generation. Magic constants are generated at build-time and are compiled into the engine binary for zero runtime overhead.
Remove transient state from the Move struct to reduce the memory footprint of each entry in the transposition table (e.g. castling rights, half-move clock, etc). This state now gets pushed/popped from a stack of history entries when doing/undoing moves.
SPRT result vs 0.5.1
Version 0.6.0 scores ~120-200 Elo over version 0.5.1 with a 100% likelihood of superiority. Null-move pruning seems to greatly improve search efficiency and tactical depth, making the engine significantly stronger overall.
Results of 0.6.0 vs 0.5.1 (10+0.1, NULL, 64MB, 8moves_v3.pgn):
Elo: 162.13 +/- 42.37, nElo: 192.04 +/- 43.24
LOS: 100.00 %, DrawRatio: 28.23 %, PairsRatio: 5.85
Games: 248, Wins: 153, Losses: 45, Draws: 50, Points: 178.0 (71.77 %)
Ptnml(0-2): [4, 9, 35, 27, 49], WL/DD Ratio: 4.00
LLR: 2.99 (101.5%) (-2.94, 2.94) [0.00, 10.00]
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SPRT ([0.00, 10.00]) completed - H1 was accepted
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