Negative extension on cutNodes based on depth

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 740ad71efee01461cc40b5992c757f2caa4db81e..fbc1755be73ceb005aaf516a01b98730e8478bee 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1097,6 +1097,10 @@ moves_loop: // When in check, search starts here
               else if (ttValue >= beta)
                   extension = -2 - !PvNode;
 
+              // If we are on a cutNode, reduce it based on depth (negative extension) (~1 Elo)
+              else if (cutNode)
+                  extension = depth > 8 && depth < 17 ? -3 : -1;
+
               // If the eval of ttMove is less than value, we reduce it (negative extension) (~1 Elo)
               else if (ttValue <= value)
                   extension = -1;