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Retire NullMoveMargin

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A code semplification that could even be a slight increase,
anyhow is a reducing pruning patch, so it is good even
at equal strenght.

After 6342 games
Mod - Orig:  1040 - 974 - 4328  ELO +3 (+- 3.5)

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-09-12 12:38:38 +01:00
parent debc815352
commit 9ab0e1bb13
1 changed files with 1 additions and 10 deletions
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11
src/search.cpp
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@ -188,12 +188,6 @@ namespace {
// Dynamic razoring margin based on depth // Dynamic razoring margin based on depth
inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * int(d)); } inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * int(d)); }
// Step 8. Null move search with verification search
// Null move margin. A null move search will not be done if the static
// evaluation of the position is more than NullMoveMargin below beta.
const Value NullMoveMargin = Value(0x200);
// Maximum depth for use of dynamic threat detection when null move fails low // Maximum depth for use of dynamic threat detection when null move fails low
const Depth ThreatDepth = 5 * ONE_PLY; const Depth ThreatDepth = 5 * ONE_PLY;
@ -1094,14 +1088,11 @@ namespace {
return refinedValue - futility_margin(depth, 0); return refinedValue - futility_margin(depth, 0);
// Step 8. Null move search with verification search (is omitted in PV nodes) // Step 8. Null move search with verification search (is omitted in PV nodes)
// When we jump directly to qsearch() we do a null move only if static value is
// at least beta. Otherwise we do a null move if static value is not more than
// NullMoveMargin under beta.
if ( !PvNode if ( !PvNode
&& !ss->skipNullMove && !ss->skipNullMove
&& depth > ONE_PLY && depth > ONE_PLY
&& !isCheck && !isCheck
&& refinedValue >= beta - (depth >= 4 * ONE_PLY ? NullMoveMargin : 0) && refinedValue >= beta
&& !value_is_mate(beta) && !value_is_mate(beta)
&& pos.non_pawn_material(pos.side_to_move())) && pos.non_pawn_material(pos.side_to_move()))
{ {