Tweaking the futility pruning formula

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 55d11003354b8da3e50c6c19648bc20bb86d721b..27f0f9870852c1dd691fc67f6dfd8679ee34274b 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1009,7 +1009,10 @@ moves_loop:  // When in check, search starts here
                 lmrDepth = std::max(lmrDepth, -1);
 
                 // Futility pruning: parent node (~13 Elo)
-                if (!ss->inCheck && lmrDepth < 13 && ss->staticEval + 77 + 124 * lmrDepth <= alpha)
+                if (!ss->inCheck && lmrDepth < 13
+                    && ss->staticEval + (bestValue < ss->staticEval - 62 ? 123 : 77)
+                           + 127 * lmrDepth
+                         <= alpha)
                     continue;
 
                 lmrDepth = std::max(lmrDepth, 0);