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Null move dynamic reduction based on value

After 994 games at 1+0

Mod vs Orig +244 =521 -229 50.75%  504.5/994 +5 ELO

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
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1 parent a530fc2 commit 314faa905a60962595d610c26727c4b603c6ed62 @mcostalba committed Nov 13, 2009
Showing with 7 additions and 1 deletion.
  1. +7 −1 src/search.cpp
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8 src/search.cpp
@@ -1314,7 +1314,13 @@ namespace {
ss[ply].currentMove = MOVE_NULL;
pos.do_null_move(st);
- int R = (depth >= 5 * OnePly ? 4 : 3); // Null move dynamic reduction
+
+ // Null move dynamic reduction based on depth
+ int R = (depth >= 5 * OnePly ? 4 : 3);
+
+ // Null move dynamic reduction based on value
+ if (approximateEval - beta > PawnValueMidgame)
+ R++;
nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);

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