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>
mcostalba · Nov 14, 2009 · 314faa9 · 314faa9
1 parent a530fc2
commit 314faa9
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/src/search.cpp b/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);