Less aggressive null move dynamic reduction

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 806a9be135e40237c1865987258b008f48efe19a..e7c4e6ca2c04d4d1b9008125dfacc68633b1e103 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -121,9 +121,6 @@ namespace {
   // Depth limit for selective search:
   Depth SelectiveDepth = 7*OnePly;
 
-  // Use dynamic LMR?
-  const bool UseDynamicLMR = false;
-
   // Use internal iterative deepening?
   const bool UseIIDAtPVNodes = true;
   const bool UseIIDAtNonPVNodes = false;
@@ -1202,7 +1199,7 @@ namespace {
 
         StateInfo st;
         pos.do_null_move(st);
-        int R = (depth >= 4 * OnePly ? 4 : 3); // Null move dynamic reduction
+        int R = (depth >= 5 * OnePly ? 4 : 3); // Null move dynamic reduction
 
         Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
 
@@ -1335,13 +1332,8 @@ namespace {
           && !move_is_castle(move)
           && !move_is_killer(move, ss[ply]))
       {
-          // LMR dynamic reduction
-          Depth R =    UseDynamicLMR
-                    && moveCount >= 2 * LMRNonPVMoves
-                    && depth > 7*OnePly ? 2*OnePly : OnePly;
-
-          ss[ply].reduction = R;
-          value = -search(pos, ss, -(beta-1), newDepth-R, ply+1, true, threadID);
+          ss[ply].reduction = OnePly;
+          value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID);
       }
       else
         value = beta; // Just to trigger next condition