VLTC search tune

XInTheDark · Disservin · commit a6fd17f27d76 · 2024-01-21T12:49:30.000+01:00
Search parameters were tuned using 152k games at 180+1.8. Passed VLTC: https://tests.stockfishchess.org/tests/view/65a7a81979aa8af82b973a20 LLR: 2.94 (-2.94,2.94) <0.00,2.00> Total: 117338 W: 29244 L: 28848 D: 59246 Ptnml(0-2): 24, 12474, 33267, 12890, 14 Passed VVLTC: https://tests.stockfishchess.org/tests/view/65ab246679aa8af82b977982 LLR: 2.94 (-2.94,2.94) <0.50,2.50> Total: 28164 W: 7239 L: 6957 D: 13968 Ptnml(0-2): 3, 2651, 8490, 2937, 1 STC Elo estimate: https://tests.stockfishchess.org/tests/view/65ac7c0979aa8af82b9792a6 Elo: -0.53 ± 2.0 (95%) LOS: 30.4% Total: 30000 W: 7688 L: 7734 D: 14578 Ptnml(0-2): 102, 3617, 7614, 3559, 108 nElo: -1.03 ± 3.9 (95%) PairsRatio: 0.99 closes #5003 Bench: 1235377
diff --git a/src/search.cpp b/src/search.cpp
@@ -55,7 +55,7 @@ namespace {
 
 // Futility margin
 Value futility_margin(Depth d, bool noTtCutNode, bool improving) {
-    Value futilityMult = 116 - 44 * noTtCutNode;
+    Value futilityMult = 114 - 47 * noTtCutNode;
     return (futilityMult * d - 3 * futilityMult / 2 * improving);
 }
 
@@ -66,15 +66,15 @@ constexpr int futility_move_count(bool improving, Depth depth) {
 // Add correctionHistory value to raw staticEval and guarantee evaluation does not hit the tablebase range
 Value to_corrected_static_eval(Value v, const Worker& w, const Position& pos) {
     auto cv = w.correctionHistory[pos.side_to_move()][pawn_structure_index<Correction>(pos)];
-    v += cv * std::abs(cv) / 16384;
+    v += cv * std::abs(cv) / 14095;
     return std::clamp(int(v), VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);
 }
 
 // History and stats update bonus, based on depth
-int stat_bonus(Depth d) { return std::min(268 * d - 352, 1153); }
+int stat_bonus(Depth d) { return std::min(265 * d - 349, 1112); }
 
 // History and stats update malus, based on depth
-int stat_malus(Depth d) { return std::min(400 * d - 354, 1201); }
+int stat_malus(Depth d) { return std::min(482 * d - 326, 1172); }
 
 // Add a small random component to draw evaluations to avoid 3-fold blindness
 Value value_draw(size_t nodes) { return VALUE_DRAW - 1 + Value(nodes & 0x2); }
@@ -334,12 +334,12 @@ void Search::Worker::iterative_deepening() {
 
             // Reset aspiration window starting size
             Value avg = rootMoves[pvIdx].averageScore;
-            delta     = Value(9) + int(avg) * avg / 14847;
+            delta     = Value(9) + int(avg) * avg / 13181;
             alpha     = std::max(avg - delta, -VALUE_INFINITE);
             beta      = std::min(avg + delta, int(VALUE_INFINITE));
 
             // Adjust optimism based on root move's averageScore (~4 Elo)
-            optimism[us]  = 121 * avg / (std::abs(avg) + 109);
+            optimism[us]  = 132 * avg / (std::abs(avg) + 98);
             optimism[~us] = -optimism[us];
 
             // Start with a small aspiration window and, in the case of a fail
@@ -769,7 +769,7 @@ Value Search::Worker::search(
     // Use static evaluation difference to improve quiet move ordering (~9 Elo)
     if (((ss - 1)->currentMove).is_ok() && !(ss - 1)->inCheck && !priorCapture)
     {
-        int bonus = std::clamp(-13 * int((ss - 1)->staticEval + ss->staticEval), -1652, 1546);
+        int bonus = std::clamp(-13 * int((ss - 1)->staticEval + ss->staticEval), -1680, 1406);
         bonus     = bonus > 0 ? 2 * bonus : bonus / 2;
         thisThread->mainHistory[~us][((ss - 1)->currentMove).from_to()] << bonus;
         if (type_of(pos.piece_on(prevSq)) != PAWN && ((ss - 1)->currentMove).type_of() != PROMOTION)
@@ -790,7 +790,7 @@ Value Search::Worker::search(
     // If eval is really low check with qsearch if it can exceed alpha, if it can't,
     // return a fail low.
     // Adjust razor margin according to cutoffCnt. (~1 Elo)
-    if (eval < alpha - 472 - (284 - 165 * ((ss + 1)->cutoffCnt > 3)) * depth * depth)
+    if (eval < alpha - 435 - (327 - 167 * ((ss + 1)->cutoffCnt > 3)) * depth * depth)
     {
         value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
         if (value < alpha)
@@ -799,17 +799,17 @@ Value Search::Worker::search(
 
     // Step 8. Futility pruning: child node (~40 Elo)
     // The depth condition is important for mate finding.
-    if (!ss->ttPv && depth < 9
+    if (!ss->ttPv && depth < 11
         && eval - futility_margin(depth, cutNode && !ss->ttHit, improving)
-               - (ss - 1)->statScore / 337
+               - (ss - 1)->statScore / 327
              >= beta
-        && eval >= beta && eval < 29008  // smaller than TB wins
+        && eval >= beta && eval < 27734  // smaller than TB wins
         && (!ttMove || ttCapture))
         return beta > VALUE_TB_LOSS_IN_MAX_PLY ? (eval + beta) / 2 : eval;
 
     // Step 9. Null move search with verification search (~35 Elo)
-    if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 17496
-        && eval >= beta && eval >= ss->staticEval && ss->staticEval >= beta - 23 * depth + 304
+    if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 17787
+        && eval >= beta && eval >= ss->staticEval && ss->staticEval >= beta - 22 * depth + 313
         && !excludedMove && pos.non_pawn_material(us) && ss->ply >= thisThread->nmpMinPly
         && beta > VALUE_TB_LOSS_IN_MAX_PLY)
     {
@@ -863,7 +863,7 @@ Value Search::Worker::search(
     if (cutNode && depth >= 8 && !ttMove)
         depth -= 2;
 
-    probCutBeta = beta + 163 - 67 * improving;
+    probCutBeta = beta + 173 - 73 * improving;
 
     // Step 11. ProbCut (~10 Elo)
     // If we have a good enough capture (or queen promotion) and a reduced search returns a value
@@ -923,7 +923,7 @@ Value Search::Worker::search(
 moves_loop:  // When in check, search starts here
 
     // Step 12. A small Probcut idea, when we are in check (~4 Elo)
-    probCutBeta = beta + 425;
+    probCutBeta = beta + 427;
     if (ss->inCheck && !PvNode && ttCapture && (tte->bound() & BOUND_LOWER)
         && tte->depth() >= depth - 4 && ttValue >= probCutBeta
         && std::abs(ttValue) < VALUE_TB_WIN_IN_MAX_PLY && std::abs(beta) < VALUE_TB_WIN_IN_MAX_PLY)
@@ -1006,15 +1006,15 @@ Value Search::Worker::search(
                 {
                     Piece capturedPiece = pos.piece_on(move.to_sq());
                     int   futilityEval =
-                      ss->staticEval + 238 + 305 * lmrDepth + PieceValue[capturedPiece]
+                      ss->staticEval + 277 + 298 * lmrDepth + PieceValue[capturedPiece]
                       + thisThread->captureHistory[movedPiece][move.to_sq()][type_of(capturedPiece)]
                           / 7;
                     if (futilityEval < alpha)
                         continue;
                 }
 
                 // SEE based pruning for captures and checks (~11 Elo)
-                if (!pos.see_ge(move, -187 * depth))
+                if (!pos.see_ge(move, -203 * depth))
                     continue;
             }
             else
@@ -1026,18 +1026,18 @@ Value Search::Worker::search(
                   + thisThread->pawnHistory[pawn_structure_index(pos)][movedPiece][move.to_sq()];
 
                 // Continuation history based pruning (~2 Elo)
-                if (lmrDepth < 6 && history < -3752 * depth)
+                if (lmrDepth < 6 && history < -4195 * depth)
                     continue;
 
-                history += 2 * thisThread->mainHistory[us][move.from_to()];
+                history += 69 * thisThread->mainHistory[us][move.from_to()] / 32;
 
-                lmrDepth += history / 7838;
+                lmrDepth += history / 6992;
                 lmrDepth = std::max(lmrDepth, -1);
 
                 // Futility pruning: parent node (~13 Elo)
-                if (!ss->inCheck && lmrDepth < 14
-                    && ss->staticEval + (bestValue < ss->staticEval - 57 ? 124 : 71)
-                           + 118 * lmrDepth
+                if (!ss->inCheck && lmrDepth < 15
+                    && ss->staticEval + (bestValue < ss->staticEval - 63 ? 137 : 64)
+                           + 111 * lmrDepth
                          <= alpha)
                     continue;
 
@@ -1064,11 +1064,11 @@ Value Search::Worker::search(
             // so changing them requires tests at these types of time controls.
             // Recursive singular search is avoided.
             if (!rootNode && move == ttMove && !excludedMove
-                && depth >= 4 - (thisThread->completedDepth > 27) + 2 * (PvNode && tte->is_pv())
+                && depth >= 4 - (thisThread->completedDepth > 31) + 2 * (PvNode && tte->is_pv())
                 && std::abs(ttValue) < VALUE_TB_WIN_IN_MAX_PLY && (tte->bound() & BOUND_LOWER)
                 && tte->depth() >= depth - 3)
             {
-                Value singularBeta  = ttValue - (66 + 58 * (ss->ttPv && !PvNode)) * depth / 64;
+                Value singularBeta  = ttValue - (58 + 52 * (ss->ttPv && !PvNode)) * depth / 64;
                 Depth singularDepth = newDepth / 2;
 
                 ss->excludedMove = move;
@@ -1082,7 +1082,7 @@ Value Search::Worker::search(
                     singularQuietLMR = !ttCapture;
 
                     // Avoid search explosion by limiting the number of double extensions
-                    if (!PvNode && value < singularBeta - 17 && ss->doubleExtensions <= 11)
+                    if (!PvNode && value < singularBeta - 16 && ss->doubleExtensions <= 12)
                     {
                         extension = 2;
                         depth += depth < 15;
@@ -1109,7 +1109,7 @@ Value Search::Worker::search(
 
                 // If we are on a cutNode but the ttMove is not assumed to fail high over current beta (~1 Elo)
                 else if (cutNode)
-                    extension = depth < 19 ? -2 : -1;
+                    extension = depth < 20 ? -2 : -1;
 
                 // If the ttMove is assumed to fail low over the value of the reduced search (~1 Elo)
                 else if (ttValue <= value)
@@ -1122,14 +1122,14 @@ Value Search::Worker::search(
 
             // Quiet ttMove extensions (~1 Elo)
             else if (PvNode && move == ttMove && move == ss->killers[0]
-                     && (*contHist[0])[movedPiece][move.to_sq()] >= 4325)
+                     && (*contHist[0])[movedPiece][move.to_sq()] >= 4111)
                 extension = 1;
 
             // Recapture extensions (~1 Elo)
             else if (PvNode && move == ttMove && move.to_sq() == prevSq
                      && thisThread->captureHistory[movedPiece][move.to_sq()]
                                                   [type_of(pos.piece_on(move.to_sq()))]
-                          > 4146)
+                          > 4484)
                 extension = 1;
         }
 
@@ -1189,10 +1189,10 @@ Value Search::Worker::search(
         ss->statScore = 2 * thisThread->mainHistory[us][move.from_to()]
                       + (*contHist[0])[movedPiece][move.to_sq()]
                       + (*contHist[1])[movedPiece][move.to_sq()]
-                      + (*contHist[3])[movedPiece][move.to_sq()] - 3817;
+                      + (*contHist[3])[movedPiece][move.to_sq()] - 4119;
 
         // Decrease/increase reduction for moves with a good/bad history (~25 Elo)
-        r -= ss->statScore / 14767;
+        r -= ss->statScore / 15373;
 
         // Step 17. Late moves reduction / extension (LMR, ~117 Elo)
         // We use various heuristics for the sons of a node after the first son has
@@ -1215,7 +1215,7 @@ Value Search::Worker::search(
             {
                 // Adjust full-depth search based on LMR results - if the result
                 // was good enough search deeper, if it was bad enough search shallower.
-                const bool doDeeperSearch    = value > (bestValue + 53 + 2 * newDepth);  // (~1 Elo)
+                const bool doDeeperSearch    = value > (bestValue + 51 + 2 * newDepth);  // (~1 Elo)
                 const bool doShallowerSearch = value < bestValue + newDepth;             // (~2 Elo)
 
                 newDepth += doDeeperSearch - doShallowerSearch;
@@ -1331,7 +1331,7 @@ Value Search::Worker::search(
                 else
                 {
                     // Reduce other moves if we have found at least one score improvement (~2 Elo)
-                    if (depth > 2 && depth < 12 && beta < 13782 && value > -11541)
+                    if (depth > 2 && depth < 12 && beta < 13195 && value > -12346)
                         depth -= 2;
 
                     assert(depth > 0);
@@ -1370,7 +1370,7 @@ Value Search::Worker::search(
     // Bonus for prior countermove that caused the fail low
     else if (!priorCapture && prevSq != SQ_NONE)
     {
-        int bonus = (depth > 6) + (PvNode || cutNode) + ((ss - 1)->statScore < -18782)
+        int bonus = (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -16797)
                   + ((ss - 1)->moveCount > 10);
         update_continuation_histories(ss - 1, pos.piece_on(prevSq), prevSq,
                                       stat_bonus(depth) * bonus);
@@ -1529,7 +1529,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
         if (bestValue > alpha)
             alpha = bestValue;
 
-        futilityBase = ss->staticEval + 182;
+        futilityBase = ss->staticEval + 186;
     }
 
     const PieceToHistory* contHist[] = {(ss - 1)->continuationHistory,
@@ -1609,7 +1609,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
                 continue;
 
             // Do not search moves with bad enough SEE values (~5 Elo)
-            if (!pos.see_ge(move, -77))
+            if (!pos.see_ge(move, -76))
                 continue;
         }
 
@@ -1764,7 +1764,7 @@ void update_all_stats(const Position& pos,
 
     if (!pos.capture_stage(bestMove))
     {
-        int bestMoveBonus = bestValue > beta + 173 ? quietMoveBonus      // larger bonus
+        int bestMoveBonus = bestValue > beta + 177 ? quietMoveBonus      // larger bonus
                                                    : stat_bonus(depth);  // smaller bonus
 
         // Increase stats for the best move in case it was a quiet move
diff --git a/src/search.h b/src/search.h
@@ -205,8 +205,8 @@ class Worker {
 
     Depth reduction(bool i, Depth d, int mn, int delta) {
         int reductionScale = reductions[d] * reductions[mn];
-        return (reductionScale + 1346 - int(delta) * 896 / int(rootDelta)) / 1024
-             + (!i && reductionScale > 880);
+        return (reductionScale + 1177 - int(delta) * 776 / int(rootDelta)) / 1024
+             + (!i && reductionScale > 842);
     }
 
     // Get a pointer to the search manager, only allowed to be called by the

Original file line number	Diff line number	Diff line change
`@@ -205,8 +205,8 @@ class Worker {`
`205`	`205`
`206`	`206`	`Depth reduction(bool i, Depth d, int mn, int delta) {`
`207`	`207`	`int reductionScale = reductions[d] * reductions[mn];`
`208`		`- return (reductionScale + 1346 - int(delta) * 896 / int(rootDelta)) / 1024`
`209`		`- + (!i && reductionScale > 880);`
	`208`	`+ return (reductionScale + 1177 - int(delta) * 776 / int(rootDelta)) / 1024`
	`209`	`+ + (!i && reductionScale > 842);`
`210`	`210`	`}`
`211`	`211`
`212`	`212`	`// Get a pointer to the search manager, only allowed to be called by the`