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Vizvezdenecsnicolet
Vizvezdenec
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Big search tuning (version 2)
One more tuning - this one includes newly introduced heuristics and some other parameters that were not included in previous one. Result of 400k games at 20+0.2 "as is". Tuning is continuing since there is probably a lot more elo to gain. STC: https://tests.stockfishchess.org/tests/view/620782edd71106ed12a497d1 LLR: 2.99 (-2.94,2.94) <0.00,2.50> Total: 38504 W: 10260 L: 9978 D: 18266 Ptnml(0-2): 142, 4249, 10230, 4447, 184 LTC: https://tests.stockfishchess.org/tests/view/6207a243d71106ed12a49d07 LLR: 2.94 (-2.94,2.94) <0.50,3.00> Total: 25176 W: 6793 L: 6546 D: 11837 Ptnml(0-2): 20, 2472, 7360, 2713, 23 closes #3931 Bench: 4784796
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‎src/search.cpp‎

Lines changed: 49 additions & 49 deletions
Original file line numberDiff line numberDiff line change
@@ -63,15 +63,15 @@ namespace {
6363

6464
// Futility margin
6565
Value futility_margin(Depth d, bool improving) {
66-
return Value(171 * (d - improving));
66+
return Value(147 * (d - improving));
6767
}
6868

6969
// Reductions lookup table, initialized at startup
7070
int Reductions[MAX_MOVES]; // [depth or moveNumber]
7171

7272
Depth reduction(bool i, Depth d, int mn, Value delta, Value rootDelta) {
7373
int r = Reductions[d] * Reductions[mn];
74-
return (r + 1575 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 1011);
74+
return (r + 1627 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 992);
7575
}
7676

7777
constexpr int futility_move_count(bool improving, Depth depth) {
@@ -80,7 +80,7 @@ namespace {
8080

8181
// History and stats update bonus, based on depth
8282
int stat_bonus(Depth d) {
83-
return std::min((7 * d + 254) * d - 206 , 1990);
83+
return std::min((8 * d + 281) * d - 241 , 1949);
8484
}
8585

8686
// Add a small random component to draw evaluations to avoid 3-fold blindness
@@ -157,7 +157,7 @@ namespace {
157157
void Search::init() {
158158

159159
for (int i = 1; i < MAX_MOVES; ++i)
160-
Reductions[i] = int((21.5 + std::log(Threads.size()) / 2) * std::log(i));
160+
Reductions[i] = int((21.14 + std::log(Threads.size()) / 2) * std::log(i));
161161
}
162162

163163

@@ -303,10 +303,10 @@ void Thread::search() {
303303

304304
multiPV = std::min(multiPV, rootMoves.size());
305305

306-
complexityAverage.set(190, 1);
306+
complexityAverage.set(211, 1);
307307

308308
trend = SCORE_ZERO;
309-
optimism[ us] = Value(34);
309+
optimism[ us] = Value(33);
310310
optimism[~us] = -optimism[us];
311311

312312
int searchAgainCounter = 0;
@@ -349,16 +349,16 @@ void Thread::search() {
349349
if (rootDepth >= 4)
350350
{
351351
Value prev = rootMoves[pvIdx].averageScore;
352-
delta = Value(16) + int(prev) * prev / 16384;
352+
delta = Value(19) + int(prev) * prev / 18321;
353353
alpha = std::max(prev - delta,-VALUE_INFINITE);
354354
beta = std::min(prev + delta, VALUE_INFINITE);
355355

356356
// Adjust trend and optimism based on root move's previousScore
357-
int tr = sigmoid(prev, 6, 13, 96, 110, 1);
357+
int tr = sigmoid(prev, 4, 11, 92, 119, 1);
358358
trend = (us == WHITE ? make_score(tr, tr / 2)
359359
: -make_score(tr, tr / 2));
360360

361-
int opt = sigmoid(prev, 7, 21, 94, 14786, 221);
361+
int opt = sigmoid(prev, 9, 18, 115, 12250, 187);
362362
optimism[ us] = Value(opt);
363363
optimism[~us] = -optimism[us];
364364
}
@@ -413,7 +413,7 @@ void Thread::search() {
413413
else
414414
break;
415415

416-
delta += delta / 4 + 3;
416+
delta += delta / 4 + 2;
417417

418418
assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
419419
}
@@ -459,17 +459,17 @@ void Thread::search() {
459459
&& !Threads.stop
460460
&& !mainThread->stopOnPonderhit)
461461
{
462-
double fallingEval = (87 + 12 * (mainThread->bestPreviousAverageScore - bestValue)
463-
+ 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 777.20;
462+
double fallingEval = (66 + 12 * (mainThread->bestPreviousAverageScore - bestValue)
463+
+ 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 809.70;
464464
fallingEval = std::clamp(fallingEval, 0.5, 1.5);
465465

466466
// If the bestMove is stable over several iterations, reduce time accordingly
467-
timeReduction = lastBestMoveDepth + 8 < completedDepth ? 1.70 : 0.91;
468-
double reduction = (1.59 + mainThread->previousTimeReduction) / (2.33 * timeReduction);
467+
timeReduction = lastBestMoveDepth + 8 < completedDepth ? 1.73 : 0.94;
468+
double reduction = (1.66 + mainThread->previousTimeReduction) / (2.35 * timeReduction);
469469
double bestMoveInstability = 1.073 + std::max(1.0, 2.25 - 9.9 / rootDepth)
470470
* totBestMoveChanges / Threads.size();
471471
int complexity = mainThread->complexityAverage.value();
472-
double complexPosition = std::clamp(1.0 + (complexity - 312) / 1750.0, 0.5, 1.5);
472+
double complexPosition = std::clamp(1.0 + (complexity - 293) / 1525.0, 0.5, 1.5);
473473

474474
double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability * complexPosition;
475475

@@ -490,7 +490,7 @@ void Thread::search() {
490490
}
491491
else if ( Threads.increaseDepth
492492
&& !mainThread->ponder
493-
&& Time.elapsed() > totalTime * 0.55)
493+
&& Time.elapsed() > totalTime * 0.49)
494494
Threads.increaseDepth = false;
495495
else
496496
Threads.increaseDepth = true;
@@ -766,7 +766,7 @@ namespace {
766766
// margin and the improving flag are used in various pruning heuristics.
767767
improvement = (ss-2)->staticEval != VALUE_NONE ? ss->staticEval - (ss-2)->staticEval
768768
: (ss-4)->staticEval != VALUE_NONE ? ss->staticEval - (ss-4)->staticEval
769-
: 200;
769+
: 184;
770770

771771
improving = improvement > 0;
772772
complexity = abs(ss->staticEval - (us == WHITE ? eg_value(pos.psq_score()) : -eg_value(pos.psq_score())));
@@ -778,7 +778,7 @@ namespace {
778778
// return a fail low.
779779
if ( !PvNode
780780
&& depth <= 6
781-
&& eval < alpha - 400 - 300 * depth * depth)
781+
&& eval < alpha - 486 - 314 * depth * depth)
782782
{
783783
value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
784784
if (value < alpha)
@@ -791,24 +791,24 @@ namespace {
791791
&& depth < 8
792792
&& eval - futility_margin(depth, improving) - (ss-1)->statScore / 256 >= beta
793793
&& eval >= beta
794-
&& eval < 17548) // 50% larger than VALUE_KNOWN_WIN, but smaller than TB wins.
794+
&& eval < 22266) // larger than VALUE_KNOWN_WIN, but smaller than TB wins.
795795
return eval;
796796

797797
// Step 9. Null move search with verification search (~22 Elo)
798798
if ( !PvNode
799799
&& (ss-1)->currentMove != MOVE_NULL
800-
&& (ss-1)->statScore < 13706
800+
&& (ss-1)->statScore < 15075
801801
&& eval >= beta
802802
&& eval >= ss->staticEval
803-
&& ss->staticEval >= beta - 19 * depth - improvement / 15 + 200 + complexity / 25
803+
&& ss->staticEval >= beta - 18 * depth - improvement / 19 + 215 + complexity / 30
804804
&& !excludedMove
805805
&& pos.non_pawn_material(us)
806806
&& (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
807807
{
808808
assert(eval - beta >= 0);
809809

810810
// Null move dynamic reduction based on depth, eval and complexity of position
811-
Depth R = std::min(int(eval - beta) / 205, 3) + depth / 3 + 4 - (complexity > 500);
811+
Depth R = std::min(int(eval - beta) / 184, 4) + depth / 3 + 4 - (complexity > 799);
812812

813813
ss->currentMove = MOVE_NULL;
814814
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
@@ -844,13 +844,13 @@ namespace {
844844
}
845845
}
846846

847-
probCutBeta = beta + 229 - 47 * improving;
847+
probCutBeta = beta + 204 - 52 * improving;
848848

849849
// Step 10. ProbCut (~4 Elo)
850850
// If we have a good enough capture and a reduced search returns a value
851851
// much above beta, we can (almost) safely prune the previous move.
852852
if ( !PvNode
853-
&& depth > 3
853+
&& depth > 4
854854
&& abs(beta) < VALUE_TB_WIN_IN_MAX_PLY
855855
// if value from transposition table is lower than probCutBeta, don't attempt probCut
856856
// there and in further interactions with transposition table cutoff depth is set to depth - 3
@@ -908,12 +908,12 @@ namespace {
908908

909909
// Step 11. If the position is not in TT, decrease depth by 2 or 1 depending on node type (~3 Elo)
910910
if ( PvNode
911-
&& depth >= 4
911+
&& depth >= 3
912912
&& !ttMove)
913913
depth -= 2;
914914

915915
if ( cutNode
916-
&& depth >= 7
916+
&& depth >= 8
917917
&& !ttMove)
918918
depth--;
919919

@@ -923,7 +923,7 @@ namespace {
923923
probCutBeta = beta + 401;
924924
if ( ss->inCheck
925925
&& !PvNode
926-
&& depth >= 4
926+
&& depth >= 2
927927
&& ttCapture
928928
&& (tte->bound() & BOUND_LOWER)
929929
&& tte->depth() >= depth - 3
@@ -1014,14 +1014,14 @@ namespace {
10141014
if ( !pos.empty(to_sq(move))
10151015
&& !givesCheck
10161016
&& !PvNode
1017-
&& lmrDepth < 6
1017+
&& lmrDepth < 7
10181018
&& !ss->inCheck
1019-
&& ss->staticEval + 392 + 207 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))]
1020-
+ captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] / 8 < alpha)
1019+
&& ss->staticEval + 424 + 138 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))]
1020+
+ captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] / 7 < alpha)
10211021
continue;
10221022

10231023
// SEE based pruning (~9 Elo)
1024-
if (!pos.see_ge(move, Value(-200) * depth))
1024+
if (!pos.see_ge(move, Value(-214) * depth))
10251025
continue;
10261026
}
10271027
else
@@ -1040,11 +1040,11 @@ namespace {
10401040
// Futility pruning: parent node (~9 Elo)
10411041
if ( !ss->inCheck
10421042
&& lmrDepth < 11
1043-
&& ss->staticEval + 131 + 137 * lmrDepth + history / 64 <= alpha)
1043+
&& ss->staticEval + 147 + 125 * lmrDepth + history / 64 <= alpha)
10441044
continue;
10451045

10461046
// Prune moves with negative SEE (~3 Elo)
1047-
if (!pos.see_ge(move, Value(-25 * lmrDepth * lmrDepth - 29 * lmrDepth)))
1047+
if (!pos.see_ge(move, Value(-23 * lmrDepth * lmrDepth - 31 * lmrDepth)))
10481048
continue;
10491049
}
10501050
}
@@ -1067,7 +1067,7 @@ namespace {
10671067
&& (tte->bound() & BOUND_LOWER)
10681068
&& tte->depth() >= depth - 3)
10691069
{
1070-
Value singularBeta = ttValue - 3 * depth;
1070+
Value singularBeta = ttValue - 4 * depth;
10711071
Depth singularDepth = (depth - 1) / 2;
10721072

10731073
ss->excludedMove = move;
@@ -1080,8 +1080,8 @@ namespace {
10801080

10811081
// Avoid search explosion by limiting the number of double extensions
10821082
if ( !PvNode
1083-
&& value < singularBeta - 71
1084-
&& ss->doubleExtensions <= 6)
1083+
&& value < singularBeta - 52
1084+
&& ss->doubleExtensions <= 8)
10851085
extension = 2;
10861086
}
10871087

@@ -1100,15 +1100,15 @@ namespace {
11001100

11011101
// Check extensions (~1 Elo)
11021102
else if ( givesCheck
1103-
&& depth > 7
1104-
&& abs(ss->staticEval) > 128)
1103+
&& depth > 8
1104+
&& abs(ss->staticEval) > 81)
11051105
extension = 1;
11061106

11071107
// Quiet ttMove extensions (~0 Elo)
11081108
else if ( PvNode
11091109
&& move == ttMove
11101110
&& move == ss->killers[0]
1111-
&& (*contHist[0])[movedPiece][to_sq(move)] >= 8932)
1111+
&& (*contHist[0])[movedPiece][to_sq(move)] >= 7546)
11121112
extension = 1;
11131113
}
11141114

@@ -1145,7 +1145,7 @@ namespace {
11451145

11461146
// Decrease reduction at some PvNodes (~2 Elo)
11471147
if ( PvNode
1148-
&& bestMoveCount <= 4)
1148+
&& bestMoveCount <= 3)
11491149
r--;
11501150

11511151
// Decrease reduction if position is or has been on the PV
@@ -1170,18 +1170,18 @@ namespace {
11701170
+ (*contHist[0])[movedPiece][to_sq(move)]
11711171
+ (*contHist[1])[movedPiece][to_sq(move)]
11721172
+ (*contHist[3])[movedPiece][to_sq(move)]
1173-
- 4142;
1173+
- 4123;
11741174

11751175
// Decrease/increase reduction for moves with a good/bad history (~30 Elo)
1176-
r -= ss->statScore / 15328;
1176+
r -= ss->statScore / 17417;
11771177

11781178
// In general we want to cap the LMR depth search at newDepth. But if reductions
11791179
// are really negative and movecount is low, we allow this move to be searched
11801180
// deeper than the first move (this may lead to hidden double extensions).
11811181
int deeper = r >= -1 ? 0
11821182
: moveCount <= 5 ? 2
1183-
: PvNode && depth > 4 ? 1
1184-
: cutNode && moveCount <= 5 ? 1
1183+
: PvNode && depth > 3 ? 1
1184+
: cutNode && moveCount <= 7 ? 1
11851185
: 0;
11861186

11871187
Depth d = std::clamp(newDepth - r, 1, newDepth + deeper);
@@ -1190,7 +1190,7 @@ namespace {
11901190

11911191
// If the son is reduced and fails high it will be re-searched at full depth
11921192
doFullDepthSearch = value > alpha && d < newDepth;
1193-
doDeeperSearch = value > (alpha + 80 + 20 * (newDepth - d));
1193+
doDeeperSearch = value > (alpha + 76 + 11 * (newDepth - d));
11941194
didLMR = true;
11951195
}
11961196
else
@@ -1211,7 +1211,7 @@ namespace {
12111211
: -stat_bonus(newDepth);
12121212

12131213
if (captureOrPromotion)
1214-
bonus /= 5;
1214+
bonus /= 6;
12151215

12161216
update_continuation_histories(ss, movedPiece, to_sq(move), bonus);
12171217
}
@@ -1335,14 +1335,14 @@ namespace {
13351335
quietsSearched, quietCount, capturesSearched, captureCount, depth);
13361336

13371337
// Bonus for prior countermove that caused the fail low
1338-
else if ( (depth >= 3 || PvNode)
1338+
else if ( (depth >= 4 || PvNode)
13391339
&& !priorCapture)
13401340
{
13411341
//Assign extra bonus if current node is PvNode or cutNode
13421342
//or fail low was really bad
13431343
bool extraBonus = PvNode
13441344
|| cutNode
1345-
|| bestValue < alpha - 99 * depth;
1345+
|| bestValue < alpha - 71 * depth;
13461346

13471347
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + extraBonus));
13481348
}
@@ -1473,7 +1473,7 @@ namespace {
14731473
if (PvNode && bestValue > alpha)
14741474
alpha = bestValue;
14751475

1476-
futilityBase = bestValue + 127;
1476+
futilityBase = bestValue + 139;
14771477
}
14781478

14791479
const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,

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