Tweak late move reductions at root

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index c1ed1f9540a059b7222a4c1663b771847dcfb0c2..0eea4127f80a36955d652301d73882f64806eca2 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1115,7 +1115,7 @@ moves_loop: // When in check, search starts from here
       // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be
       // re-searched at full depth.
       if (    depth >= 3
       // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be
       // re-searched at full depth.
       if (    depth >= 3

-          &&  moveCount > 1 + 2 * rootNode
+          &&  moveCount > 1 + rootNode + (rootNode && bestValue < alpha)

           && (!rootNode || thisThread->best_move_count(move) == 0)
           && (  !captureOrPromotion
               || moveCountPruning
           && (!rootNode || thisThread->best_move_count(move) == 0)
           && (  !captureOrPromotion
               || moveCountPruning