Reduce repetitions branches

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index c7e6fff053c7778cb469d6a4b1c9841279596783..d9b41cb35c4f87ee900106caf7ea0900962e239c 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1143,6 +1143,11 @@ moves_loop: // When in check, search starts here
       // Decrease reduction if ttMove has been singularly extended (~1 Elo)
       if (singularQuietLMR)
           r--;
+      
+      // Increase reduction on repetition (~1 Elo)
+      if (   move == (ss-4)->currentMove
+          && pos.has_repeated())
+          r += 2;
 
       // Increase reduction if next ply has a lot of fail high (~5 Elo)
       if ((ss+1)->cutoffCnt > 3)
@@ -1211,10 +1216,9 @@ moves_loop: // When in check, search starts here
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth - (r > 3), !cutNode);
       }
 
-      // For PV nodes only, do a full PV search on the first move or after a fail
-      // high (in the latter case search only if value < beta), otherwise let the
-      // parent node fail low with value <= alpha and try another move.
-      if (PvNode && (moveCount == 1 || (value > alpha && (rootNode || value < beta))))
+      // For PV nodes only, do a full PV search on the first move or after a fail high,
+      // otherwise let the parent node fail low with value <= alpha and try another move.
+      if (PvNode && (moveCount == 1 || value > alpha))
       {
           (ss+1)->pv = pv;
           (ss+1)->pv[0] = MOVE_NONE;