CMH Fix: Exclude captures for TT move refutation penalty

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 4aecad1cca7981096828d15b3217d6564330f611..865e477144042c2a99577ac8179e066718016585 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -902,7 +902,7 @@ moves_loop: // When in check and at SpNode search starts from here
           // Futility pruning: parent node
           if (predictedDepth < 7 * ONE_PLY)
           {
-              futilityValue =  ss->staticEval + futility_margin(predictedDepth) + 256;
+              futilityValue = ss->staticEval + futility_margin(predictedDepth) + 256;
 
               if (futilityValue <= alpha)
               {
@@ -959,7 +959,10 @@ moves_loop: // When in check and at SpNode search starts from here
                                         [pos.piece_on(to_sq(move))][to_sq(move)] <= VALUE_ZERO))
               ss->reduction += ONE_PLY;
 
-          if (move == countermove)
+          if (    move == countermove
+              || (   History[pos.piece_on(to_sq(move))][to_sq(move)] > VALUE_ZERO
+                  && CounterMovesHistory[pos.piece_on(prevMoveSq)][prevMoveSq]
+                                        [pos.piece_on(to_sq(move))][to_sq(move)] > VALUE_ZERO))
               ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
 
           // Decrease reduction for moves that escape a capture
@@ -1425,7 +1428,7 @@ moves_loop: // When in check and at SpNode search starts from here
     }
 
     // Extra penalty for TT move in previous ply when it gets refuted
-    if (is_ok((ss-2)->currentMove) && (ss-1)->currentMove == (ss-1)->ttMove)
+    if (is_ok((ss-2)->currentMove) && (ss-1)->currentMove == (ss-1)->ttMove && !pos.captured_piece_type())
     {
         Square prevPrevSq = to_sq((ss-2)->currentMove);
         HistoryStats& ttMoveCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];