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Try to prune also when approximateEval < beta

Now we always try to filter out moves, we will have
more wasted evaluation calls, but also more pruned
nodes.

After 786 games

Mod vs Orig +196 =413 -177 +8 ELO

Verified also against Rybka it increases score to 50-51%

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
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mcostalba committed Dec 1, 2009
1 parent ae0b965 commit 3f3365221b571f1e712f1dd66574a866e858256d
Showing with 8 additions and 11 deletions.
  1. +8 −11 src/search.cpp
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@@ -1517,19 +1517,16 @@ namespace {
continue;
// Value based pruning
- if (approximateEval < beta)
- {
- if (futilityValue == VALUE_NONE)
- futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
+ if (futilityValue == VALUE_NONE)
+ futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
- futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin;
+ futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin;
- if (futilityValueScaled < beta)
- {
- if (futilityValueScaled > bestValue)
- bestValue = futilityValueScaled;
- continue;
- }
+ if (futilityValueScaled < beta)
+ {
+ if (futilityValueScaled > bestValue)
+ bestValue = futilityValueScaled;
+ continue;
}
}

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