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Cap evaluation based null move extra reduction to three plies

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It's a zero elo patch, and a reasonable safeguard against uncontrolled extreme reductions.

STC:
ELO: -0.08 +-2.0 (95%) LOS: 46.9%
Total: 40000 W: 6728 L: 6737 D: 26535

LTC:
ELO: -0.14 +-1.8 (95%) LOS: 44.0%
Total: 40000 W: 5557 L: 5573 D: 28870

Bench: 7201830
This commit is contained in:
Joona Kiiski
2014-09-25 20:42:25 +01:00
parent d6613b7589
commit 7ed15af371
1 changed files with 1 additions and 2 deletions
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3
src/search.cpp
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@@ -567,8 +567,7 @@ namespace {
// Null move dynamic reduction based on depth and value // Null move dynamic reduction based on depth and value
Depth R = 3 * ONE_PLY Depth R = 3 * ONE_PLY
+ depth / 4 + depth / 4
+ (abs(beta) < VALUE_KNOWN_WIN ? int(eval - beta) / PawnValueMg * ONE_PLY + std::min(int(eval - beta) / PawnValueMg, 3) * ONE_PLY;
: DEPTH_ZERO);
pos.do_null_move(st); pos.do_null_move(st);
(ss+1)->skipNullMove = true; (ss+1)->skipNullMove = true;