Assorted search parameter tune

STC https://tests.stockfishchess.org/tests/view/5f31219090816720665374ec
LLR: 2.96 (-2.94,2.94) {-0.50,1.50}
Total: 3376 W: 487 L: 359 D: 2530
Ptnml(0-2): 17, 253, 1042, 337, 39

LTC https://tests.stockfishchess.org/tests/view/5f3127f79081672066537502
LLR: 2.93 (-2.94,2.94) {0.25,1.75}
Total: 8360 W: 581 L: 475 D: 7304
Ptnml(0-2): 11, 407, 3238, 513, 11

closes https://github.com/official-stockfish/Stockfish/pull/2971

bench: 4733874

diff --git a/src/search.cpp b/src/search.cpp
index 3d2bb4222953bfe78c29f495f20481b219db312f..676427f704234642ad84d440afc448ace1fcc66e 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -63,9 +63,9 @@ namespace {
   constexpr uint64_t TtHitAverageResolution = 1024;
 
   // Razor and futility margins
-  constexpr int RazorMargin = 527;
+  constexpr int RazorMargin = 510;
   Value futility_margin(Depth d, bool improving) {
-    return Value(227 * (d - improving));
+    return Value(223 * (d - improving));
   }
 
   // Reductions lookup table, initialized at startup
@@ -73,7 +73,7 @@ namespace {
 
   Depth reduction(bool i, Depth d, int mn) {
     int r = Reductions[d] * Reductions[mn];
-    return (r + 570) / 1024 + (!i && r > 1018);
+    return (r + 509) / 1024 + (!i && r > 894);
   }
 
   constexpr int futility_move_count(bool improving, Depth depth) {
@@ -82,7 +82,7 @@ namespace {
 
   // History and stats update bonus, based on depth
   int stat_bonus(Depth d) {
-    return d > 15 ? 27 : 17 * d * d + 133 * d - 134;
+    return d > 13 ? 29 : 17 * d * d + 134 * d - 134;
   }
 
   // Add a small random component to draw evaluations to avoid 3fold-blindness
@@ -192,7 +192,7 @@ namespace {
 void Search::init() {
 
   for (int i = 1; i < MAX_MOVES; ++i)
-      Reductions[i] = int((24.8 + std::log(Threads.size())) * std::log(i));
+      Reductions[i] = int((22.0 + std::log(Threads.size())) * std::log(i));
 }
 
 
@@ -403,12 +403,12 @@ void Thread::search() {
           if (rootDepth >= 4)
           {
               Value prev = rootMoves[pvIdx].previousScore;
-              delta = Value(19);
+              delta = Value(17);
               alpha = std::max(prev - delta,-VALUE_INFINITE);
               beta  = std::min(prev + delta, VALUE_INFINITE);
 
               // Adjust contempt based on root move's previousScore (dynamic contempt)
-              int dct = ct + (110 - ct / 2) * prev / (abs(prev) + 140);
+              int dct = ct + (105 - ct / 2) * prev / (abs(prev) + 149);
 
               contempt = (us == WHITE ?  make_score(dct, dct / 2)
                                       : -make_score(dct, dct / 2));
@@ -506,13 +506,13 @@ void Thread::search() {
           && !Threads.stop
           && !mainThread->stopOnPonderhit)
       {
-          double fallingEval = (296 + 6 * (mainThread->bestPreviousScore - bestValue)
-                                    + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 725.0;
+          double fallingEval = (318 + 6 * (mainThread->bestPreviousScore - bestValue)
+                                    + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 825.0;
           fallingEval = Utility::clamp(fallingEval, 0.5, 1.5);
 
           // If the bestMove is stable over several iterations, reduce time accordingly
-          timeReduction = lastBestMoveDepth + 10 < completedDepth ? 1.92 : 0.95;
-          double reduction = (1.47 + mainThread->previousTimeReduction) / (2.22 * timeReduction);
+          timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.92 : 0.95;
+          double reduction = (1.47 + mainThread->previousTimeReduction) / (2.32 * timeReduction);
 
           // Use part of the gained time from a previous stable move for the current move
           for (Thread* th : Threads)
@@ -537,7 +537,7 @@ void Thread::search() {
           }
           else if (   Threads.increaseDepth
                    && !mainThread->ponder
-                   && Time.elapsed() > totalTime * 0.56)
+                   && Time.elapsed() > totalTime * 0.58)
                    Threads.increaseDepth = false;
           else
                    Threads.increaseDepth = true;
@@ -824,10 +824,10 @@ namespace {
     // Step 9. Null move search with verification search (~40 Elo)
     if (   !PvNode
         && (ss-1)->currentMove != MOVE_NULL
-        && (ss-1)->statScore < 23824
+        && (ss-1)->statScore < 22977
         &&  eval >= beta
         &&  eval >= ss->staticEval
-        &&  ss->staticEval >= beta - 28 * depth - 28 * improving + 94 * ttPv + 200
+        &&  ss->staticEval >= beta - 30 * depth - 28 * improving + 84 * ttPv + 182
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -835,7 +835,7 @@ namespace {
         assert(eval - beta >= 0);
 
         // Null move dynamic reduction based on depth and value
-        Depth R = (737 + 77 * depth) / 246 + std::min(int(eval - beta) / 192, 3);
+        Depth R = (817 + 71 * depth) / 213 + std::min(int(eval - beta) / 192, 3);
 
         ss->currentMove = MOVE_NULL;
         ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
@@ -1028,17 +1028,17 @@ moves_loop: // When in check, search starts from here
                   continue;
 
               // Futility pruning: parent node (~5 Elo)
-              if (   lmrDepth < 8
+              if (   lmrDepth < 7
                   && !ss->inCheck
-                  && ss->staticEval + 284 + 188 * lmrDepth <= alpha
+                  && ss->staticEval + 283 + 170 * lmrDepth <= alpha
                   &&  (*contHist[0])[movedPiece][to_sq(move)]
                     + (*contHist[1])[movedPiece][to_sq(move)]
                     + (*contHist[3])[movedPiece][to_sq(move)]
-                    + (*contHist[5])[movedPiece][to_sq(move)] / 2 < 28388)
+                    + (*contHist[5])[movedPiece][to_sq(move)] / 2 < 27376)
                   continue;
 
               // Prune moves with negative SEE (~20 Elo)
-              if (!pos.see_ge(move, Value(-(29 - std::min(lmrDepth, 17)) * lmrDepth * lmrDepth)))
+              if (!pos.see_ge(move, Value(-(29 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
                   continue;
           }
           else
@@ -1055,12 +1055,12 @@ moves_loop: // When in check, search starts from here
                   && !(PvNode && abs(bestValue) < 2)
                   && PieceValue[MG][type_of(movedPiece)] >= PieceValue[MG][type_of(pos.piece_on(to_sq(move)))]
                   && !ss->inCheck
-                  && ss->staticEval + 178 + 261 * lmrDepth
+                  && ss->staticEval + 169 + 244 * lmrDepth
                      + PieceValue[MG][type_of(pos.piece_on(to_sq(move)))] <= alpha)
                   continue;
 
               // See based pruning
-              if (!pos.see_ge(move, Value(-202) * depth)) // (~25 Elo)
+              if (!pos.see_ge(move, Value(-221) * depth)) // (~25 Elo)
                   continue;
           }
       }
@@ -1166,7 +1166,7 @@ moves_loop: // When in check, search starts from here
               || moveCountPruning
               || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
               || cutNode
-              || thisThread->ttHitAverage < 415 * TtHitAverageResolution * TtHitAverageWindow / 1024))
+              || thisThread->ttHitAverage < 427 * TtHitAverageResolution * TtHitAverageWindow / 1024))
       {
           Depth r = reduction(improving, depth, moveCount);
 
@@ -1178,7 +1178,7 @@ moves_loop: // When in check, search starts from here
               r--;
 
           // Decrease reduction if the ttHit running average is large
-          if (thisThread->ttHitAverage > 473 * TtHitAverageResolution * TtHitAverageWindow / 1024)
+          if (thisThread->ttHitAverage > 509 * TtHitAverageResolution * TtHitAverageWindow / 1024)
               r--;
 
           // Reduction if other threads are searching this position
@@ -1221,17 +1221,17 @@ moves_loop: // When in check, search starts from here
                              + (*contHist[0])[movedPiece][to_sq(move)]
                              + (*contHist[1])[movedPiece][to_sq(move)]
                              + (*contHist[3])[movedPiece][to_sq(move)]
-                             - 4826;
+                             - 5287;
 
               // Decrease/increase reduction by comparing opponent's stat score (~10 Elo)
-              if (ss->statScore >= -100 && (ss-1)->statScore < -112)
+              if (ss->statScore >= -106 && (ss-1)->statScore < -104)
                   r--;
 
-              else if ((ss-1)->statScore >= -125 && ss->statScore < -138)
+              else if ((ss-1)->statScore >= -119 && ss->statScore < -140)
                   r++;
 
               // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
-              r -= ss->statScore / 14615;
+              r -= ss->statScore / 14884;
           }
           else
           {
@@ -1241,7 +1241,7 @@ moves_loop: // When in check, search starts from here
 
             // Unless giving check, this capture is likely bad
             if (   !givesCheck
-                && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 211 * depth <= alpha)
+                && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 213 * depth <= alpha)
                 r++;
           }
 
@@ -1503,7 +1503,7 @@ moves_loop: // When in check, search starts from here
         if (PvNode && bestValue > alpha)
             alpha = bestValue;
 
-        futilityBase = bestValue + 141;
+        futilityBase = bestValue + 145;
     }
 
     const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
@@ -1754,7 +1754,7 @@ moves_loop: // When in check, search starts from here
     }
 
     if (depth > 11 && ss->ply < MAX_LPH)
-        thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 6);
+        thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 7);
   }
 
   // When playing with strength handicap, choose best move among a set of RootMoves