Reduce repetitions branches

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index d911593c03177f569afca9a9d6a6359750d42714..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)