Use increased LMR horizont only after a null move

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 7e2f9727291df6bffbd90b218ecb854c3f549cf6..08e3a997c4d3c63365e24040e1803d298e8b3075 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -201,6 +201,12 @@ namespace {
   // Depth limit for use of dynamic threat detection
   Depth ThreatDepth; // heavy SMP read access
 
+  // Last seconds noise filtering (LSN)
+  const bool UseLSNFiltering = true;
+  const int LSNTime = 4000; // In milliseconds
+  const Value LSNValue = value_from_centipawns(200);
+  bool loseOnTime = false;
+
   // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.
   // There is heavy SMP read access on these arrays
   Depth CheckExtension[2], SingleReplyExtension[2], PawnPushTo7thExtension[2];
@@ -367,7 +373,10 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
   // Read UCI option values
   TT.set_size(get_option_value_int("Hash"));
   if (button_was_pressed("Clear Hash"))
+  {
       TT.clear();
+      loseOnTime = false; // reset at the beginning of a new game
+  }
 
   bool PonderingEnabled = get_option_value_bool("Ponder");
   MultiPV = get_option_value_int("MultiPV");
@@ -400,10 +409,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
   if (UseLogFile)
       LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
 
-  bool UseLSNFiltering = get_option_value_bool("LSN filtering");
-  int LSNTime = get_option_value_int("LSN Time Margin (sec)") * 1000;
-  Value LSNValue = value_from_centipawns(get_option_value_int("LSN Value Margin"));
-
   MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly;
   MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
 
@@ -481,20 +486,19 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
 
 
   // We're ready to start thinking. Call the iterative deepening loop function
-  static bool looseOnTime = false;
-
+  //
   // FIXME we really need to cleanup all this LSN ugliness
-  if (!looseOnTime)
+  if (!loseOnTime)
   {
       Value v = id_loop(pos, searchMoves);
-      looseOnTime = (   UseLSNFiltering
+      loseOnTime = (   UseLSNFiltering
                      && myTime < LSNTime
                      && myIncrement == 0
                      && v < -LSNValue);
   }
   else
   {
-      looseOnTime = false; // reset for next match
+      loseOnTime = false; // reset for next match
       while (SearchStartTime + myTime + 1000 > get_system_time())
           ; // wait here
       id_loop(pos, searchMoves); // to fail gracefully
@@ -1239,9 +1243,8 @@ namespace {
 
         StateInfo st;
         pos.do_null_move(st);
-        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);
+        Value nullValue = -search(pos, ss, -(beta-1), depth-4*OnePly, ply+1, false, threadID);
 
         pos.undo_null_move();
 
@@ -1360,7 +1363,7 @@ namespace {
 
       // Try to reduce non-pv search depth by one ply if move seems not problematic,
       // if the move fails high will be re-searched at full depth.
-      if (    depth >= 2*OnePly
+      if (    depth >= (ss[ply-1].currentMove == MOVE_NULL ? 3 : 2) * OnePly
           &&  moveCount >= LMRNonPVMoves
           && !dangerous
           && !moveIsCapture
@@ -1488,7 +1491,6 @@ namespace {
     else if (tte && tte->type() == VALUE_TYPE_EVAL)
     {
         // Use the cached evaluation score if possible
-        assert(tte->value() == evaluate(pos, ei, threadID));
         assert(ei.futilityMargin == Value(0));
 
         staticValue = tte->value();
@@ -1561,9 +1563,7 @@ namespace {
       // Don't search captures and checks with negative SEE values
       if (   !isCheck
           && !move_is_promotion(move)
-          && (pos.midgame_value_of_piece_on(move_from(move)) >
-              pos.midgame_value_of_piece_on(move_to(move)))
-          &&  pos.see(move) < 0)
+          &&  pos.see_sign(move) < 0)
           continue;
 
       // Make and search the move.
@@ -2240,7 +2240,7 @@ namespace {
     if (   pvNode
         && capture
         && pos.type_of_piece_on(move_to(m)) != PAWN
-        && pos.see(m) >= 0)
+        && pos.see_sign(m) >= 0)
     {
         result += OnePly/2;
         *dangerous = true;
@@ -2313,7 +2313,7 @@ namespace {
         && threat != MOVE_NONE
         && piece_is_slider(pos.piece_on(tfrom))
         && bit_is_set(squares_between(tfrom, tto), mto)
-        && pos.see(m) >= 0)
+        && pos.see_sign(m) >= 0)
         return false;
 
     return true;