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Try razoring only for depth > OnePly

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Because razoring verification after qsearch() cuts more
then 40% of candidates, do not waste a costly qsearch for
nodes at depth one that will be probably discarded anyway
by futility.

Also tight razoring conditions to keep dangerous false
negatives below 0,05%. Still not clear if it is enough.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2008-12-24 11:27:07 +01:00
parent 2feb9d5100
commit 8cd5cb930d
1 changed files with 5 additions and 2 deletions
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7
src/search.cpp
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@ -1239,10 +1239,13 @@ namespace {
// Null move search not allowed, try razoring // Null move search not allowed, try razoring
else if ( !value_is_mate(beta) else if ( !value_is_mate(beta)
&& approximateEval < beta - RazorMargin && approximateEval < beta - RazorMargin
&& depth < RazorDepth) && depth < RazorDepth
&& depth > OnePly
&& ttMove == MOVE_NONE
&& !pos.has_pawn_on_7th(pos.side_to_move()))
{ {
Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
if (v < beta - RazorMargin / 2) if (v < beta - RazorMargin / 2 - int(depth - OnePly) * RazorMargin / 8)
return v; return v;
} }