kate/BadFish
1
0
Fork 0
mirror of https://github.com/sockspls/badfish synced 2025-04-30 08:43:09 +00:00
Code Issues Releases Wiki Activity

Do more futility pruning in qsearch

Browse source 
This patch introduces a third futility pruning heuristic in qsearch. The idea is
that the static exchange evaluation is much worse than the difference between
futility base and alpha. Thus we can assume that the probability of the move
being good enough to beat alpha is low so it can be pruned.

Passed STC:
https://tests.stockfishchess.org/tests/view/64fc982a5dab775b5359dc83
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 36576 W: 9484 L: 9170 D: 17922
Ptnml(0-2): 121, 4119, 9495, 4431, 122

Passed LTC:
https://tests.stockfishchess.org/tests/view/64fcc7935dab775b5359e1a9
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 135408 W: 34556 L: 34041 D: 66811
Ptnml(0-2): 56, 14462, 38165, 14953, 68

closes https://github.com/official-stockfish/Stockfish/pull/4781

Bench: 1330793
This commit is contained in:
Michael Chaly 2023-09-11 15:37:18 +03:00 • committed by Disservin
parent 6d85f43e26
commit ef22829616
1 changed files with 12 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
src/search.cpp
View file

@ -1549,17 +1549,29 @@ moves_loop: // When in check, search starts here
futilityValue = futilityBase + PieceValue[pos.piece_on(to_sq(move))];
// If static eval + value of piece we are going to capture is much lower
// than alpha we can prune this move
if (futilityValue <= alpha)
{
bestValue = std::max(bestValue, futilityValue);
continue;
}
// If static eval is much lower than alpha and move is not winning material
// we can prune this move
if (futilityBase <= alpha && !pos.see_ge(move, VALUE_ZERO + 1))
{
bestValue = std::max(bestValue, futilityBase);
continue;
}
// If static exchange evaluation is much worse than what is needed to not
// fall below alpha we can prune this move
if (futilityBase > alpha && !pos.see_ge(move, (alpha - futilityBase) * 4))
{
bestValue = alpha;
continue;
}
}
// We prune after the second quiet check evasion move, where being 'in check' is