Combo of various parameter tweaks

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index c48b74bcc76ddc0761cdb9c44d961dffa4b0f2c0..b400b8f8b0c4c409d4c004e6047f12468e8d2959 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -793,7 +793,7 @@ namespace {
         && (ss-1)->statScore < 23767
         &&  eval >= beta
         &&  eval >= ss->staticEval
-        &&  ss->staticEval >= beta - 20 * depth - 22 * improving + 168 * ss->ttPv + 159
+        &&  ss->staticEval >= beta - 20 * depth - 22 * improving + 168 * ss->ttPv + 177
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -801,7 +801,7 @@ namespace {
         assert(eval - beta >= 0);
 
         // Null move dynamic reduction based on depth and value
-        Depth R = (1090 + 81 * depth) / 256 + std::min(int(eval - beta) / 205, 3);
+        Depth R = std::min(int(eval - beta) / 205, 3) + depth / 3 + 4;
 
         ss->currentMove = MOVE_NULL;
         ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
@@ -903,12 +903,17 @@ namespace {
          ss->ttPv = ttPv;
     }
 
-    // Step 10. If the position is not in TT, decrease depth by 2
+    // Step 10. If the position is not in TT, decrease depth by 2 or 1 depending on node type
     if (   PvNode
         && depth >= 6
         && !ttMove)
         depth -= 2;
 
+    if (   cutNode
+        && depth >= 9
+        && !ttMove)
+        depth--;
+
 moves_loop: // When in check, search starts here
 
     ttCapture = ttMove && pos.capture_or_promotion(ttMove);
@@ -1018,15 +1023,16 @@ moves_loop: // When in check, search starts here
           else
           {
               // Continuation history based pruning (~20 Elo)
-              if (   lmrDepth < 5
-                  && (*contHist[0])[movedPiece][to_sq(move)] < 23 - 23 * depth * depth
-                  && (*contHist[1])[movedPiece][to_sq(move)] < 23 - 23 * depth * depth)
+              if (lmrDepth < 5
+                  && (*contHist[0])[movedPiece][to_sq(move)]
+                  + (*contHist[1])[movedPiece][to_sq(move)]
+                  + (*contHist[3])[movedPiece][to_sq(move)] < -3000 * depth + 3000)
                   continue;
 
               // Futility pruning: parent node (~5 Elo)
               if (   !ss->inCheck
-                  && lmrDepth < 7
-                  && ss->staticEval + 174 + 157 * lmrDepth <= alpha)
+                  && lmrDepth < 8
+                  && ss->staticEval + 172 + 145 * lmrDepth <= alpha)
                   continue;
 
               // Prune moves with negative SEE (~20 Elo)
@@ -1051,7 +1057,7 @@ moves_loop: // When in check, search starts here
           && (tte->bound() & BOUND_LOWER)
           &&  tte->depth() >= depth - 3)
       {
-          Value singularBeta = ttValue - 2 * depth;
+          Value singularBeta = ttValue - 3 * depth;
           Depth singularDepth = (depth - 1) / 2;
 
           ss->excludedMove = move;
@@ -1093,6 +1099,14 @@ moves_loop: // When in check, search starts here
                   return beta;
           }
       }
+
+      // Capture extensions for PvNodes and cutNodes
+      else if (   (PvNode || cutNode)
+               && captureOrPromotion
+               && moveCount != 1)
+          extension = 1;
+
+      // Check extensions
       else if (   givesCheck
                && depth > 6
                && abs(ss->staticEval) > Value(100))
@@ -1173,8 +1187,8 @@ moves_loop: // When in check, search starts here
 
           // In general we want to cap the LMR depth search at newDepth. But if
           // reductions are really negative and movecount is low, we allow this move
-          // to be searched deeper than the first move, unless ttMove was extended by 2.
-          Depth d = std::clamp(newDepth - r, 1, newDepth + (r < -1 && moveCount <= 5 && !doubleExtension));
+          // to be searched deeper than the first move in specific cases.
+          Depth d = std::clamp(newDepth - r, 1, newDepth + (r < -1 && (moveCount <= 5 || (depth > 6 && PvNode)) && !doubleExtension));
 
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
 
@@ -1316,7 +1330,7 @@ moves_loop: // When in check, search starts here
     // Bonus for prior countermove that caused the fail low
     else if (   (depth >= 3 || PvNode)
              && !priorCapture)
-        update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth));
+        update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + (PvNode || cutNode)));
 
     if (PvNode)
         bestValue = std::min(bestValue, maxValue);