Parameter Tweaks

This patch is a parameter tweak that passed both STC and LTC tests.

STC:
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 80944 W: 21557 L: 21189 D: 38198
Ptnml(0-2): 192, 8883, 22028, 9103, 266
https://tests.stockfishchess.org/tests/view/63b07fe2d421d8f75795a03b

LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 30440 W: 8296 L: 8007 D: 14137
Ptnml(0-2): 6, 2893, 9143, 3162, 16
https://tests.stockfishchess.org/tests/view/63b167d02ab1290f961644db

closes https://github.com/official-stockfish/Stockfish/pull/4318

Bench: 4182223

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 3b6cbbcd8a644d47fb599107a44a565e7276533d..d5cda3d80e86ef9a9f779abc1aa6b39c2bb7108e 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -1056,7 +1056,7 @@ Value Eval::evaluate(const Position& pos, int* complexity) {
   // We use the much less accurate but faster Classical eval when the NNUE
   // option is set to false. Otherwise we use the NNUE eval unless the
   // PSQ advantage is decisive and several pieces remain. (~3 Elo)
-  bool useClassical = !useNNUE || (pos.count<ALL_PIECES>() > 7 && abs(psq) > 1760);
+  bool useClassical = !useNNUE || (pos.count<ALL_PIECES>() > 7 && abs(psq) > 1781);
 
   if (useClassical)
       v = Evaluation<NO_TRACE>(pos).value();
@@ -1071,8 +1071,8 @@ Value Eval::evaluate(const Position& pos, int* complexity) {
       Value nnue = NNUE::evaluate(pos, true, &nnueComplexity);
 
       // Blend nnue complexity with (semi)classical complexity
-      nnueComplexity = (  412 * nnueComplexity
-                        + 428 * abs(psq - nnue)
+      nnueComplexity = (  406 * nnueComplexity
+                        + 424 * abs(psq - nnue)
                         + (optimism  > 0 ? int(optimism) * int(psq - nnue) : 0)
                         ) / 1024;
 
@@ -1080,12 +1080,12 @@ Value Eval::evaluate(const Position& pos, int* complexity) {
       if (complexity)
           *complexity = nnueComplexity;
 
-      optimism = optimism * (278 + nnueComplexity) / 256;
-      v = (nnue * scale + optimism * (scale - 755)) / 1024;
+      optimism = optimism * (272 + nnueComplexity) / 256;
+      v = (nnue * scale + optimism * (scale - 748)) / 1024;
   }
 
   // Damp down the evaluation linearly when shuffling
-  v = v * (197 - pos.rule50_count()) / 214;
+  v = v * (200 - pos.rule50_count()) / 214;
 
   // Guarantee evaluation does not hit the tablebase range
   v = std::clamp(v, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);

diff --git a/src/search.cpp b/src/search.cpp
index dd24036604efb6b8aa3fe8e242cc08c0f93ed0ec..d0ed44fa16a8c34ebc5e1648bd93ff6b580f558c 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -63,7 +63,7 @@ namespace {
 
   // Futility margin
   Value futility_margin(Depth d, bool improving) {
-    return Value(165 * (d - improving));
+    return Value(158 * (d - improving));
   }
 
   // Reductions lookup table, initialized at startup
@@ -71,7 +71,7 @@ namespace {
 
   Depth reduction(bool i, Depth d, int mn, Value delta, Value rootDelta) {
     int r = Reductions[d] * Reductions[mn];
-    return (r + 1642 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 916);
+    return (r + 1460 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 937);
   }
 
   constexpr int futility_move_count(bool improving, Depth depth) {
@@ -81,7 +81,7 @@ namespace {
 
   // History and stats update bonus, based on depth
   int stat_bonus(Depth d) {
-    return std::min((12 * d + 282) * d - 349 , 1480);
+    return std::min((11 * d + 284) * d - 363 , 1650);
   }
 
   // Add a small random component to draw evaluations to avoid 3-fold blindness
@@ -307,7 +307,7 @@ void Thread::search() {
 
   multiPV = std::min(multiPV, rootMoves.size());
 
-  complexityAverage.set(155, 1);
+  complexityAverage.set(153, 1);
 
   optimism[us] = optimism[~us] = VALUE_ZERO;
 
@@ -351,12 +351,12 @@ void Thread::search() {
           if (rootDepth >= 4)
           {
               Value prev = rootMoves[pvIdx].averageScore;
-              delta = Value(10) + int(prev) * prev / 15620;
+              delta = Value(10) + int(prev) * prev / 15400;
               alpha = std::max(prev - delta,-VALUE_INFINITE);
               beta  = std::min(prev + delta, VALUE_INFINITE);
 
               // Adjust optimism based on root move's previousScore
-              int opt = 118 * prev / (std::abs(prev) + 169);
+              int opt = 116 * prev / (std::abs(prev) + 170);
               optimism[ us] = Value(opt);
               optimism[~us] = -optimism[us];
           }
@@ -753,7 +753,7 @@ namespace {
     // Use static evaluation difference to improve quiet move ordering (~4 Elo)
     if (is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture)
     {
-        int bonus = std::clamp(-19 * int((ss-1)->staticEval + ss->staticEval), -1914, 1914);
+        int bonus = std::clamp(-19 * int((ss-1)->staticEval + ss->staticEval), -1940, 1940);
         thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus;
     }
 
@@ -763,13 +763,13 @@ namespace {
     // margin and the improving flag are used in various pruning heuristics.
     improvement =   (ss-2)->staticEval != VALUE_NONE ? ss->staticEval - (ss-2)->staticEval
                   : (ss-4)->staticEval != VALUE_NONE ? ss->staticEval - (ss-4)->staticEval
-                  :                                    168;
+                  :                                    172;
     improving = improvement > 0;
 
     // Step 7. Razoring (~1 Elo).
     // If eval is really low check with qsearch if it can exceed alpha, if it can't,
     // return a fail low.
-    if (eval < alpha - 369 - 254 * depth * depth)
+    if (eval < alpha - 394 - 255 * depth * depth)
     {
         value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
         if (value < alpha)
@@ -780,18 +780,18 @@ namespace {
     // The depth condition is important for mate finding.
     if (   !ss->ttPv
         &&  depth < 8
-        &&  eval - futility_margin(depth, improving) - (ss-1)->statScore / 303 >= beta
+        &&  eval - futility_margin(depth, improving) - (ss-1)->statScore / 304 >= beta
         &&  eval >= beta
-        &&  eval < 28031) // larger than VALUE_KNOWN_WIN, but smaller than TB wins
+        &&  eval < 28580) // larger than VALUE_KNOWN_WIN, but smaller than TB wins
         return eval;
 
     // Step 9. Null move search with verification search (~35 Elo)
     if (   !PvNode
         && (ss-1)->currentMove != MOVE_NULL
-        && (ss-1)->statScore < 17139
+        && (ss-1)->statScore < 18200
         &&  eval >= beta
         &&  eval >= ss->staticEval
-        &&  ss->staticEval >= beta - 20 * depth - improvement / 13 + 233 + complexity / 25
+        &&  ss->staticEval >= beta - 20 * depth - improvement / 14 + 235 + complexity / 24
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -799,7 +799,7 @@ namespace {
         assert(eval - beta >= 0);
 
         // Null move dynamic reduction based on depth, eval and complexity of position
-        Depth R = std::min(int(eval - beta) / 168, 7) + depth / 3 + 4 - (complexity > 861);
+        Depth R = std::min(int(eval - beta) / 165, 6) + depth / 3 + 4 - (complexity > 800);
 
         ss->currentMove = MOVE_NULL;
         ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
@@ -835,7 +835,7 @@ namespace {
         }
     }
 
-    probCutBeta = beta + 191 - 54 * improving;
+    probCutBeta = beta + 180 - 54 * improving;
 
     // Step 10. ProbCut (~10 Elo)
     // If we have a good enough capture and a reduced search returns a value
@@ -904,7 +904,7 @@ namespace {
 moves_loop: // When in check, search starts here
 
     // Step 12. A small Probcut idea, when we are in check (~4 Elo)
-    probCutBeta = beta + 417;
+    probCutBeta = beta + 402;
     if (   ss->inCheck
         && !PvNode
         && depth >= 2
@@ -999,12 +999,12 @@ moves_loop: // When in check, search starts here
                   && !PvNode
                   && lmrDepth < 7
                   && !ss->inCheck
-                  && ss->staticEval + 180 + 201 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))]
+                  && ss->staticEval + 185 + 203 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))]
                    + captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] / 6 < alpha)
                   continue;
 
               // SEE based pruning (~11 Elo)
-              if (!pos.see_ge(move, Value(-222) * depth))
+              if (!pos.see_ge(move, Value(-220) * depth))
                   continue;
           }
           else
@@ -1015,7 +1015,7 @@ moves_loop: // When in check, search starts here
 
               // Continuation history based pruning (~2 Elo)
               if (   lmrDepth < 5
-                  && history < -3875 * (depth - 1))
+                  && history < -4180 * (depth - 1))
                   continue;
 
               history += 2 * thisThread->mainHistory[us][from_to(move)];
@@ -1023,11 +1023,11 @@ moves_loop: // When in check, search starts here
               // Futility pruning: parent node (~13 Elo)
               if (   !ss->inCheck
                   && lmrDepth < 13
-                  && ss->staticEval + 106 + 145 * lmrDepth + history / 52 <= alpha)
+                  && ss->staticEval + 103 + 136 * lmrDepth + history / 53 <= alpha)
                   continue;
 
               // Prune moves with negative SEE (~4 Elo)
-              if (!pos.see_ge(move, Value(-24 * lmrDepth * lmrDepth - 15 * lmrDepth)))
+              if (!pos.see_ge(move, Value(-25 * lmrDepth * lmrDepth - 16 * lmrDepth)))
                   continue;
           }
       }
@@ -1092,14 +1092,14 @@ moves_loop: // When in check, search starts here
           // Check extensions (~1 Elo)
           else if (   givesCheck
                    && depth > 9
-                   && abs(ss->staticEval) > 82)
+                   && abs(ss->staticEval) > 78)
               extension = 1;
 
           // Quiet ttMove extensions (~1 Elo)
           else if (   PvNode
                    && move == ttMove
                    && move == ss->killers[0]
-                   && (*contHist[0])[movedPiece][to_sq(move)] >= 5177)
+                   && (*contHist[0])[movedPiece][to_sq(move)] >= 5600)
               extension = 1;
       }
 
@@ -1161,10 +1161,10 @@ moves_loop: // When in check, search starts here
                      + (*contHist[0])[movedPiece][to_sq(move)]
                      + (*contHist[1])[movedPiece][to_sq(move)]
                      + (*contHist[3])[movedPiece][to_sq(move)]
-                     - 4433;
+                     - 4467;
 
       // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
-      r -= ss->statScore / (13000 + 4152 * (depth > 7 && depth < 19));
+      r -= ss->statScore / (12800 + 4410 * (depth > 7 && depth < 19));
 
       // Step 17. Late moves reduction / extension (LMR, ~117 Elo)
       // We use various heuristics for the sons of a node after the first son has
@@ -1188,7 +1188,7 @@ moves_loop: // When in check, search starts here
           {
               // Adjust full depth search based on LMR results - if result
               // was good enough search deeper, if it was bad enough search shallower
-              const bool doDeeperSearch = value > (alpha + 64 + 11 * (newDepth - d));
+              const bool doDeeperSearch = value > (alpha + 66 + 11 * (newDepth - d));
               const bool doEvenDeeperSearch = value > alpha + 582 && ss->doubleExtensions <= 5;
               const bool doShallowerSearch = value < bestValue + newDepth;
 
@@ -1353,7 +1353,7 @@ moves_loop: // When in check, search starts here
                          quietsSearched, quietCount, capturesSearched, captureCount, depth);
 
     // Bonus for prior countermove that caused the fail low
-    else if (   (depth >= 5 || PvNode || bestValue < alpha - 62 * depth)
+    else if (   (depth >= 5 || PvNode || bestValue < alpha - 65 * depth)
              && !priorCapture)
     {
         //Assign extra bonus if current node is PvNode or cutNode
@@ -1361,7 +1361,7 @@ moves_loop: // When in check, search starts here
         bool extraBonus =    PvNode
                           || cutNode;
 
-        bool doubleExtraBonus = extraBonus && bestValue < alpha - 85 * depth;
+        bool doubleExtraBonus = extraBonus && bestValue < alpha - 88 * depth;
 
         update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + extraBonus + doubleExtraBonus));
     }
@@ -1488,7 +1488,7 @@ moves_loop: // When in check, search starts here
         if (PvNode && bestValue > alpha)
             alpha = bestValue;
 
-        futilityBase = bestValue + 153;
+        futilityBase = bestValue + 158;
     }
 
     const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
@@ -1690,7 +1690,7 @@ moves_loop: // When in check, search starts here
 
     if (!pos.capture(bestMove))
     {
-        int bonus2 = bestValue > beta + 137 ? bonus1               // larger bonus
+        int bonus2 = bestValue > beta + 146 ? bonus1               // larger bonus
                                             : stat_bonus(depth);   // smaller bonus
 
         // Increase stats for the best move in case it was a quiet move