Gaia, a free and strong UCI chess engine written in Rust.
See also: gaiachess.fr — the original Gaia website
Gaia 4 is a complete rewrite from C to Rust — not a single line of the original code survived. Back after 20 years.
See also: gaiachess.fr — the original Gaia website
Gaia 4 is a complete rewrite from C to Rust — not a single line of the original code survived. Back after 20 years.
Author: Jean-Francois Romang Rating Chess Engines Diary CEDR=3681
Gaia what's new?
New default network gaianet-t2b-e044 (+4.8 ±3.6 Elo vs e017, SPRT, 18 420 games).
Time management. New allocation; the previous one left most of the clock
unused in blitz. Move Overhead is now a UCI option (default 40 ms).
Tablebases
A Nalimov "mated in 0" was scored as a draw: a mate in two could be shown for
many moves without being played.
Mates longer than 128 plies were printed as a centipawn score (+312) instead
of mate N.
DTM scores respect the fifty-move rule; Syzygy cursed wins and blessed losses
at the root are no longer reported as decisive.
Analysing a seven-piece position with WDL-only tables could go silent for over
a minute and alternate between +2 and +200.
New option NalimovCache (MiB, default 256).
Search
A second occurrence of a position could be scored 0.00 as a repetition.
The move played and the last line printed always come from the last completed
iteration.
On the losing side of a decided position the search could run to ply 127 and
announce a mate far longer than the real one; scores such as -101.61 no
longer appear.
Null-move pruning is disabled in sparse minor-piece endings; its entry margin
and ProbCut were adjusted.
UCI
A progress line is printed after one second without output.
UCI_ShowCurrLine, UCI_ShowRefutations and cpuload are supported.
The last info line before bestmove is the elected thread's exact line.
Debug Log File appends instead of overwriting, with millisecond timestamps.
Speed. AVX2 network evaluation is 12 % faster; move generation tables were
reworked on AVX2 and ARM64.
Thanks to David Rabel for the tournament logs and analyses behind most of these
fixes.
Gaia 4.2.5 vs other engines:
| Chess System Tal 2.07 E1019 | 2.5/4 | +1 | 4 games |
| Deep Shredder 14 | 2.5/4 | +1 | 4 games |
| Devre 7.0 JA | 2/4 | +0 | 4 games |
| Fritz 21 | 2/4 | +0 | 4 games |
| Bread 4.0.0 | 2/4 | +0 | 4 games |
| Quanticade Phoenix 4.0 | 2/4 | +0 | 4 games |
| Caissa 1.26 JA | 2/4 | +0 | 4 games |
| Rebel 16.5 | 2/4 | +0 | 4 games |
| Astra 7.0 | 2/4 | +0 | 4 games |
| Viridithas 20.0.0 | 2/4 | +0 | 4 games |
| Tcheran 13.0 | 2/4 | +0 | 4 games |
| Renegade 1.3.1 | 2/4 | +0 | 4 games |
| RubiChess 01082026 | 2/4 | +0 | 4 games |
| Cinder 0.6.1 | 2/4 | +0 | 4 games |
| Dragon 3.3 | 2/4 | +0 | 4 games |
| Hobbes 3.0 | 2/4 | +0 | 4 games |
| Obsidian 16.15 | 2/4 | +0 | 4 games |
| Avalanche 4.0.0 | 2/4 | +0 | 4 games |
| Integral 7.0.0 | 1.5/4 | -1 | 4 games |
| Raphael 4.3.0 dev-4a2c693 | 1.5/4 | -1 | 4 games |
| Reckless 0.10.0 | 1.5/4 | -1 | 4 games |
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