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Do more futility pruning for cutNodes that are not in TT

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This is somewhat similar to IIR for cutnodes but instead of reducing
depth for cutnodes that don't have tt move we reduce margin multiplier
in futility pruning for cutnodes that are not in TT.

Passed STC:
https://tests.stockfishchess.org/tests/view/64b244b90cdec37b95734c5b
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 75552 W: 19404 L: 19029 D: 37119
Ptnml(0-2): 233, 8806, 19378, 9071, 288

Passed LTC:
https://tests.stockfishchess.org/tests/view/64b3ae5a0cdec37b95736516
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 104988 W: 27152 L: 26697 D: 51139
Ptnml(0-2): 41, 11259, 29446, 11700, 48

closes https://github.com/official-stockfish/Stockfish/pull/4700

bench 1727577
This commit is contained in:
Michael Chaly 2023-07-19 11:58:02 +03:00 • committed by Joost VandeVondele
parent 1444837887
commit 5ea1cbc778
1 changed files with 3 additions and 3 deletions
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6
src/search.cpp
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@ -63,8 +63,8 @@ namespace {
enum NodeType { NonPV, PV, Root }; enum NodeType { NonPV, PV, Root };
// Futility margin // Futility margin
Value futility_margin(Depth d, bool improving) { Value futility_margin(Depth d, bool noTtCutNode, bool improving) {
return Value(140 * (d - improving)); return Value((140 - 40 * noTtCutNode) * (d - improving));
} }
// Reductions lookup table initialized at startup // Reductions lookup table initialized at startup
@ -767,7 +767,7 @@ namespace {
// The depth condition is important for mate finding. // The depth condition is important for mate finding.
if ( !ss->ttPv if ( !ss->ttPv
&& depth < 9 && depth < 9
&& eval - futility_margin(depth, improving) - (ss-1)->statScore / 306 >= beta && eval - futility_margin(depth, cutNode && !ss->ttHit, improving) - (ss-1)->statScore / 306 >= beta
&& eval >= beta && eval >= beta
&& eval < 24923) // larger than VALUE_KNOWN_WIN, but smaller than TB wins && eval < 24923) // larger than VALUE_KNOWN_WIN, but smaller than TB wins
return eval; return eval;