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VVLTC search tune
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Tuned with 85k games at VVLTC.

VVLTC 1st sprt: https://tests.stockfishchess.org/tests/view/6648b836308cceea45533ad7
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 14880 W: 3890 L: 3652 D: 7338
Ptnml(0-2): 0, 1255, 4694, 1489, 2

VVLTC 2nd sprt: https://tests.stockfishchess.org/tests/view/6648c34f308cceea45533b4f
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 24984 W: 6502 L: 6235 D: 12247
Ptnml(0-2): 1, 2178, 7867, 2445, 1

closes official-stockfish#5264

Bench: 1198142
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@XInTheDark @vondele
XInTheDark authored and vondele committed May 18, 2024
1 parent 2694fce commit 99f1bac
Showing 1 changed file with 42 additions and 42 deletions.
84 changes: 42 additions & 42 deletions src/search.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -59,9 +59,9 @@ static constexpr double EvalLevel[10] = {0.981, 0.956, 0.895, 0.949, 0.913,

// Futility margin
Value futility_margin(Depth d, bool noTtCutNode, bool improving, bool oppWorsening) {
Value futilityMult = 131 - 48 * noTtCutNode;
Value improvingDeduction = 2 * improving * futilityMult;
Value worseningDeduction = 330 * oppWorsening * futilityMult / 1024;
Value futilityMult = 127 - 48 * noTtCutNode;
Value improvingDeduction = 65 * improving * futilityMult / 32;
Value worseningDeduction = 334 * oppWorsening * futilityMult / 1024;

return futilityMult * d - improvingDeduction - worseningDeduction;
}
Expand All @@ -73,15 +73,15 @@ 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) / 7179;
v += cv * std::abs(cv) / 6047;
return std::clamp(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::clamp(200 * d - 280, 16, 1495); }
int stat_bonus(Depth d) { return std::clamp(187 * d - 288, 17, 1548); }

// History and stats update malus, based on depth
int stat_malus(Depth d) { return (d < 4 ? 586 * d - 284 : 1639); }
int stat_malus(Depth d) { return (d < 4 ? 630 * d - 281 : 1741); }

// 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); }
Expand Down Expand Up @@ -311,12 +311,12 @@ void Search::Worker::iterative_deepening() {

// Reset aspiration window starting size
Value avg = rootMoves[pvIdx].averageScore;
delta = 10 + avg * avg / 9474;
delta = 10 + avg * avg / 9828;
alpha = std::max(avg - delta, -VALUE_INFINITE);
beta = std::min(avg + delta, VALUE_INFINITE);

// Adjust optimism based on root move's averageScore (~4 Elo)
optimism[us] = 117 * avg / (std::abs(avg) + 88);
optimism[us] = 116 * avg / (std::abs(avg) + 84);
optimism[~us] = -optimism[us];

// Start with a small aspiration window and, in the case of a fail
Expand Down Expand Up @@ -503,10 +503,10 @@ void Search::Worker::clear() {
for (StatsType c : {NoCaptures, Captures})
for (auto& to : continuationHistory[inCheck][c])
for (auto& h : to)
h->fill(-62);
h->fill(-60);

for (size_t i = 1; i < reductions.size(); ++i)
reductions[i] = int((21.19 + std::log(size_t(options["Threads"])) / 2) * std::log(i));
reductions[i] = int((21.69 + std::log(size_t(options["Threads"])) / 2) * std::log(i));

refreshTable.clear(networks);
}
Expand Down Expand Up @@ -739,7 +739,7 @@ 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(-12 * int((ss - 1)->staticEval + ss->staticEval), -1749, 1584);
int bonus = std::clamp(-11 * int((ss - 1)->staticEval + ss->staticEval), -1729, 1517);
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)
Expand All @@ -762,7 +762,7 @@ 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 - 473 - (308 - 138 * ((ss + 1)->cutoffCnt > 3)) * depth * depth)
if (eval < alpha - 474 - (326 - 139 * ((ss + 1)->cutoffCnt > 3)) * depth * depth)
{
value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
if (value < alpha)
Expand All @@ -773,21 +773,21 @@ Value Search::Worker::search(
// The depth condition is important for mate finding.
if (!ss->ttPv && depth < 11
&& eval - futility_margin(depth, cutNode && !ss->ttHit, improving, opponentWorsening)
- (ss - 1)->statScore / 258
- (ss - 1)->statScore / 252
>= beta
&& eval >= beta && eval < VALUE_TB_WIN_IN_MAX_PLY && (!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 < 16079
&& eval >= beta && ss->staticEval >= beta - 21 * depth + 324 && !excludedMove
if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 15246
&& eval >= beta && ss->staticEval >= beta - 21 * depth + 366 && !excludedMove
&& pos.non_pawn_material(us) && ss->ply >= thisThread->nmpMinPly
&& beta > VALUE_TB_LOSS_IN_MAX_PLY)
{
assert(eval - beta >= 0);

// Null move dynamic reduction based on depth and eval
Depth R = std::min(int(eval - beta) / 144, 6) + depth / 3 + 5;
Depth R = std::min(int(eval - beta) / 152, 6) + depth / 3 + 5;

ss->currentMove = Move::null();
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
Expand Down Expand Up @@ -835,7 +835,7 @@ Value Search::Worker::search(
// Step 11. ProbCut (~10 Elo)
// If we have a good enough capture (or queen promotion) and a reduced search returns a value
// much above beta, we can (almost) safely prune the previous move.
probCutBeta = beta + 177 - 65 * improving;
probCutBeta = beta + 176 - 65 * improving;
if (
!PvNode && depth > 3
&& std::abs(beta) < VALUE_TB_WIN_IN_MAX_PLY
Expand Down Expand Up @@ -891,7 +891,7 @@ 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 + 428;
probCutBeta = beta + 440;
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)
Expand Down Expand Up @@ -975,15 +975,15 @@ Value Search::Worker::search(
// Futility pruning for captures (~2 Elo)
if (!givesCheck && lmrDepth < 7 && !ss->inCheck)
{
Value futilityValue = ss->staticEval + 305 + 272 * lmrDepth
Value futilityValue = ss->staticEval + 276 + 256 * lmrDepth
+ PieceValue[capturedPiece] + captHist / 7;
if (futilityValue <= alpha)
continue;
}

// SEE based pruning for captures and checks (~11 Elo)
int seeHist = std::clamp(captHist / 32, -185 * depth, 182 * depth);
if (!pos.see_ge(move, -176 * depth - seeHist))
int seeHist = std::clamp(captHist / 32, -177 * depth, 175 * depth);
if (!pos.see_ge(move, -183 * depth - seeHist))
continue;
}
else
Expand All @@ -994,18 +994,18 @@ Value Search::Worker::search(
+ thisThread->pawnHistory[pawn_structure_index(pos)][movedPiece][move.to_sq()];

// Continuation history based pruning (~2 Elo)
if (lmrDepth < 6 && history < -4360 * depth)
if (lmrDepth < 6 && history < -4076 * depth)
continue;

history += 2 * thisThread->mainHistory[us][move.from_to()];

lmrDepth += history / 4507;
lmrDepth += history / 4401;

Value futilityValue =
ss->staticEval + (bestValue < ss->staticEval - 54 ? 142 : 55) + 132 * lmrDepth;
ss->staticEval + (bestValue < ss->staticEval - 53 ? 151 : 57) + 140 * lmrDepth;

// Futility pruning: parent node (~13 Elo)
if (!ss->inCheck && lmrDepth < 11 && futilityValue <= alpha)
if (!ss->inCheck && lmrDepth < 10 && futilityValue <= alpha)
{
if (bestValue <= futilityValue && std::abs(bestValue) < VALUE_TB_WIN_IN_MAX_PLY
&& futilityValue < VALUE_TB_WIN_IN_MAX_PLY)
Expand All @@ -1016,7 +1016,7 @@ Value Search::Worker::search(
lmrDepth = std::max(lmrDepth, 0);

// Prune moves with negative SEE (~4 Elo)
if (!pos.see_ge(move, -27 * lmrDepth * lmrDepth))
if (!pos.see_ge(move, -26 * lmrDepth * lmrDepth))
continue;
}
}
Expand All @@ -1036,11 +1036,11 @@ 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 > 33) + ss->ttPv
&& depth >= 4 - (thisThread->completedDepth > 35) + ss->ttPv
&& std::abs(ttValue) < VALUE_TB_WIN_IN_MAX_PLY && (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3)
{
Value singularBeta = ttValue - (59 + 49 * (ss->ttPv && !PvNode)) * depth / 64;
Value singularBeta = ttValue - (57 + 50 * (ss->ttPv && !PvNode)) * depth / 64;
Depth singularDepth = newDepth / 2;

ss->excludedMove = move;
Expand All @@ -1050,14 +1050,14 @@ Value Search::Worker::search(

if (value < singularBeta)
{
int doubleMargin = 285 * PvNode - 228 * !ttCapture;
int doubleMargin = 298 * PvNode - 209 * !ttCapture;
int tripleMargin =
121 + 238 * PvNode - 259 * !ttCapture + 117 * (ss->ttPv || !ttCapture);
117 + 252 * PvNode - 270 * !ttCapture + 111 * (ss->ttPv || !ttCapture);

extension = 1 + (value < singularBeta - doubleMargin)
+ (value < singularBeta - tripleMargin);

depth += ((!PvNode) && (depth < 14));
depth += ((!PvNode) && (depth < 15));
}

// Multi-cut pruning
Expand Down Expand Up @@ -1092,7 +1092,7 @@ Value Search::Worker::search(
else if (PvNode && move == ttMove && move.to_sq() == prevSq
&& thisThread->captureHistory[movedPiece][move.to_sq()]
[type_of(pos.piece_on(move.to_sq()))]
> 4041)
> 3748)
extension = 1;
}

Expand Down Expand Up @@ -1143,10 +1143,10 @@ 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()] - 5313;
+ (*contHist[1])[movedPiece][move.to_sq()] - 5266;

// Decrease/increase reduction for moves with a good/bad history (~8 Elo)
r -= ss->statScore / (16145 - std::min(depth, 15) * 102);
r -= ss->statScore / (14519 - std::min(depth, 15) * 103);

// Step 17. Late moves reduction / extension (LMR, ~117 Elo)
if (depth >= 2 && moveCount > 1 + rootNode)
Expand All @@ -1165,7 +1165,7 @@ 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 + 41 + 2 * newDepth); // (~1 Elo)
const bool doDeeperSearch = value > (bestValue + 40 + 2 * newDepth); // (~1 Elo)
const bool doShallowerSearch = value < bestValue + newDepth; // (~2 Elo)

newDepth += doDeeperSearch - doShallowerSearch;
Expand Down Expand Up @@ -1326,9 +1326,9 @@ Value Search::Worker::search(
// Bonus for prior countermove that caused the fail low
else if (!priorCapture && prevSq != SQ_NONE)
{
int bonus = (depth > 4) + (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -14323)
+ ((ss - 1)->moveCount > 10) + (!ss->inCheck && bestValue <= ss->staticEval - 120)
+ (!(ss - 1)->inCheck && bestValue <= -(ss - 1)->staticEval - 76);
int bonus = (depth > 4) + (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -13241)
+ ((ss - 1)->moveCount > 10) + (!ss->inCheck && bestValue <= ss->staticEval - 127)
+ (!(ss - 1)->inCheck && bestValue <= -(ss - 1)->staticEval - 74);
update_continuation_histories(ss - 1, pos.piece_on(prevSq), prevSq,
stat_bonus(depth) * bonus);
thisThread->mainHistory[~us][((ss - 1)->currentMove).from_to()]
Expand Down Expand Up @@ -1494,7 +1494,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
if (bestValue > alpha)
alpha = bestValue;

futilityBase = ss->staticEval + 259;
futilityBase = ss->staticEval + 264;
}

const PieceToHistory* contHist[] = {(ss - 1)->continuationHistory,
Expand Down Expand Up @@ -1566,11 +1566,11 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
+ (*contHist[1])[pos.moved_piece(move)][move.to_sq()]
+ thisThread->pawnHistory[pawn_structure_index(pos)][pos.moved_piece(move)]
[move.to_sq()]
<= 4057)
<= 4348)
continue;

// Do not search moves with bad enough SEE values (~5 Elo)
if (!pos.see_ge(move, -68))
if (!pos.see_ge(move, -63))
continue;
}

Expand Down Expand Up @@ -1636,7 +1636,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,

Depth Search::Worker::reduction(bool i, Depth d, int mn, int delta) {
int reductionScale = reductions[d] * reductions[mn];
return (reductionScale + 1284 - delta * 755 / rootDelta) / 1024 + (!i && reductionScale > 1133);
return (reductionScale + 1147 - delta * 755 / rootDelta) / 1024 + (!i && reductionScale > 1125);
}

// elapsed() returns the time elapsed since the search started. If the
Expand Down

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