Decrease depth for cutnodes with no tt move

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index ed5dd6c2c7ad5aab3e39b26cb038833c3a6b58d2..a4b17d9de6ea565439d08fb87bbae1a7516acb87 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -903,12 +903,17 @@ namespace {
          ss->ttPv = ttPv;
     }
 
-    // Step 10. If the position is not in TT, decrease depth by 2
+    // Step 10. If the position is not in TT, decrease depth by 2 or 1 depending on node type
     if (   PvNode
         && depth >= 6
         && !ttMove)
         depth -= 2;
 
+    if (   cutNode
+        && depth >= 9
+        && !ttMove)
+        depth--;
+
 moves_loop: // When in check, search starts here
 
     ttCapture = ttMove && pos.capture_or_promotion(ttMove);