Simplify pruning rule

STC: http://tests.stockfishchess.org/tests/view/583df86d0ebc5903140c5481
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 43283 W: 7761 L: 7678 D: 27844

LTC: http://tests.stockfishchess.org/tests/view/583f42670ebc5903140c5525
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 56587 W: 7232 L: 7157 D: 42198

bench: 5084980

diff --git a/src/search.cpp b/src/search.cpp
index 2e4ec5ec0889672162fdf25c77317a4aade7165e..b916264a790e03f1544ec5a9f7578fa2f16059ea 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -950,9 +950,10 @@ moves_loop: // When in check search starts from here
           }
           else if (depth < 7 * ONE_PLY && !extension)
           {
-              Value v = Value(-35 * depth / ONE_PLY * depth / ONE_PLY);
-              if (ss->staticEval != VALUE_NONE)
-                  v += ss->staticEval - alpha - 200;
+              Value v = -Value(399 + 35 * depth / ONE_PLY * depth / ONE_PLY);
+
+              if (PvNode)
+                  v += beta - alpha - 1;
 
               if (!pos.see_ge(move, v))
                   continue;