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Assorted search parameter tune
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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 #2971

bench: 4733874
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@unaiic @vondele
unaiic authored and vondele committed Aug 10, 2020
1 parent 21df37d commit 220ef1d
Showing 1 changed file with 30 additions and 30 deletions.
60 changes: 30 additions & 30 deletions src/search.cpp
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Expand Up @@ -63,17 +63,17 @@ 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
int Reductions[MAX_MOVES]; // [depth or moveNumber]

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) {
Expand All @@ -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
Expand Down Expand Up @@ -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));
}


Expand Down Expand Up @@ -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));
Expand Down Expand Up @@ -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)
Expand All @@ -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;
Expand Down Expand Up @@ -824,18 +824,18 @@ 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))
{
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];
Expand Down Expand Up @@ -1028,17 +1028,17 @@ namespace {
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
Expand All @@ -1055,12 +1055,12 @@ namespace {
&& !(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;
}
}
Expand Down Expand Up @@ -1166,7 +1166,7 @@ namespace {
|| 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);

Expand All @@ -1178,7 +1178,7 @@ namespace {
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
Expand Down Expand Up @@ -1221,17 +1221,17 @@ namespace {
+ (*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
{
Expand All @@ -1241,7 +1241,7 @@ namespace {

// 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++;
}

Expand Down Expand Up @@ -1503,7 +1503,7 @@ namespace {
if (PvNode && bestValue > alpha)
alpha = bestValue;

futilityBase = bestValue + 141;
futilityBase = bestValue + 145;
}

const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
Expand Down Expand Up @@ -1754,7 +1754,7 @@ namespace {
}

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
Expand Down

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