Reduce more CUT nodes only if parent node is reduced

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 4ca9e9b8c0f834d8ccbcf91e3defdeae9fed24bd..bfab6a4e1cd2829408f1e0d849f3962ab9fd77db 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -948,6 +948,10 @@ split_point_start: // At split points actual search starts from here
           &&  move != ss->killers[1])
       {
           ss->reduction = reduction<PvNode>(depth, moveCount);
+
+          if (!PvNode && cutNode && (ss-1)->reduction)
+              ss->reduction += ONE_PLY;
+
           if (move == countermoves[0] || move == countermoves[1])
               ss->reduction = std::max(DEPTH_ZERO, ss->reduction-ONE_PLY);