Use complexity in search

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 2fd8245ec2c1eecbaa7bef97e33860794ff335c7..c81496d17a35aa6a00374c9ec9be9115ea720c49 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2022 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -589,7 +589,7 @@ namespace {
     bool givesCheck, improving, didLMR, priorCapture;
     bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture;
     Piece movedPiece;
-    int moveCount, captureCount, quietCount, bestMoveCount, improvement;
+    int moveCount, captureCount, quietCount, bestMoveCount, improvement, complexity;
 
     // Step 1. Initialize node
     ss->inCheck        = pos.checkers();
@@ -760,6 +760,7 @@ namespace {
         ss->staticEval = eval = VALUE_NONE;
         improving = false;
         improvement = 0;
+        complexity = 0;
         goto moves_loop;
     }
     else if (ss->ttHit)
@@ -803,6 +804,7 @@ namespace {
                   :                                    200;
 
     improving = improvement > 0;
+    complexity = abs(ss->staticEval - (us == WHITE ? eg_value(pos.psq_score()) : -eg_value(pos.psq_score())));
 
     // Step 7. Futility pruning: child node (~25 Elo).
     // The depth condition is important for mate finding.
@@ -818,7 +820,7 @@ namespace {
         && (ss-1)->statScore < 23767
         &&  eval >= beta
         &&  eval >= ss->staticEval
-        &&  ss->staticEval >= beta - 20 * depth - improvement / 15 + 204
+        &&  ss->staticEval >= beta - 20 * depth - improvement / 15 + 204 + complexity / 25
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -1040,7 +1042,7 @@ moves_loop: // When in check, search starts here
                   continue;
 
               // SEE based pruning (~9 Elo)
-              if (!pos.see_ge(move, Value(-218) * depth))
+              if (!pos.see_ge(move, Value(-217) * depth))
                   continue;
           }
           else
@@ -1051,7 +1053,7 @@ moves_loop: // When in check, search starts here
 
               // Continuation history based pruning (~2 Elo)
               if (   lmrDepth < 5
-                  && history < -3000 * depth + 3000)
+                  && history < -3875 * (depth - 1))
                   continue;
 
               history += thisThread->mainHistory[us][from_to(move)];
@@ -1059,7 +1061,7 @@ moves_loop: // When in check, search starts here
               // Futility pruning: parent node (~9 Elo)
               if (   !ss->inCheck
                   && lmrDepth < 8
-                  && ss->staticEval + 142 + 139 * lmrDepth + history / 64 <= alpha)
+                  && ss->staticEval + 138 + 137 * lmrDepth + history / 64 <= alpha)
                   continue;
 
               // Prune moves with negative SEE (~3 Elo)