// History and stats update bonus, based on depth
int stat_bonus(Depth d) {
- return std::min((12 * d + 282) * d - 349 , 1594);
+ return std::min((12 * d + 282) * d - 349 , 1480);
}
// Add a small random component to draw evaluations to avoid 3-fold blindness
// Send again PV info if we have a new best thread
if (bestThread != this)
- sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth, -VALUE_INFINITE, VALUE_INFINITE) << sync_endl;
+ sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth) << sync_endl;
sync_cout << "bestmove " << UCI::move(bestThread->rootMoves[0].pv[0], rootPos.is_chess960());
complexityAverage.set(155, 1);
- trend = SCORE_ZERO;
optimism[us] = optimism[~us] = VALUE_ZERO;
int searchAgainCounter = 0;
alpha = std::max(prev - delta,-VALUE_INFINITE);
beta = std::min(prev + delta, VALUE_INFINITE);
- // Adjust trend and optimism based on root move's previousScore
- int tr = 116 * prev / (std::abs(prev) + 89);
- trend = (us == WHITE ? make_score(tr, tr / 2)
- : -make_score(tr, tr / 2));
-
+ // Adjust optimism based on root move's previousScore
int opt = 118 * prev / (std::abs(prev) + 169);
optimism[ us] = Value(opt);
optimism[~us] = -optimism[us];
&& multiPV == 1
&& (bestValue <= alpha || bestValue >= beta)
&& Time.elapsed() > 3000)
- sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl;
+ sync_cout << UCI::pv(rootPos, rootDepth) << sync_endl;
// In case of failing low/high increase aspiration window and
// re-search, otherwise exit the loop.
if ( mainThread
&& (Threads.stop || pvIdx + 1 == multiPV || Time.elapsed() > 3000))
- sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl;
+ sync_cout << UCI::pv(rootPos, rootDepth) << sync_endl;
}
if (!Threads.stop)
// Step 7. Razoring.
// If eval is really low check with qsearch if it can exceed alpha, if it can't,
// return a fail low.
- if ( depth <= 7
- && eval < alpha - 369 - 254 * depth * depth)
+ if (eval < alpha - 369 - 254 * depth * depth)
{
value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
if (value < alpha)
&& depth < 8
&& eval - futility_margin(depth, improving) - (ss-1)->statScore / 303 >= beta
&& eval >= beta
- && eval < 28031) // larger than VALUE_KNOWN_WIN, but smaller than TB wins.
+ && eval < 28031) // larger than VALUE_KNOWN_WIN, but smaller than TB wins
return eval;
// Step 9. Null move search with verification search (~22 Elo)
{
assert(probCutBeta < VALUE_INFINITE);
- MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, depth - 3, &captureHistory);
+ MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory);
while ((move = mp.next_move()) != MOVE_NONE)
if (move != excludedMove && pos.legal(move))
|| givesCheck)
{
// Futility pruning for captures (~0 Elo)
- if ( !pos.empty(to_sq(move))
- && !givesCheck
+ if ( !givesCheck
&& !PvNode
&& lmrDepth < 7
&& !ss->inCheck
if (singularQuietLMR)
r--;
- // Increase reduction if next ply has a lot of fail high else reset count to 0
- if ((ss+1)->cutoffCnt > 3 && !PvNode)
+ // Decrease reduction if we move a threatened piece (~1 Elo)
+ if ( depth > 9
+ && (mp.threatenedPieces & from_sq(move)))
+ r--;
+
+ // Increase reduction if next ply has a lot of fail high
+ if ((ss+1)->cutoffCnt > 3)
r++;
ss->statScore = 2 * thisThread->mainHistory[us][from_to(move)]
- 4433;
// Decrease/increase reduction for moves with a good/bad history (~30 Elo)
- r -= ss->statScore / 13628;
+ r -= ss->statScore / (13000 + 4152 * (depth > 7 && depth < 19));
// In general we want to cap the LMR depth search at newDepth, but when
// reduction is negative, we allow this move a limited search extension
// Do full depth search when reduced LMR search fails high
if (value > alpha && d < newDepth)
{
+ // Adjust full depth search based on LMR results - if result
+ // was good enough search deeper, if it was bad enough search shallower
const bool doDeeperSearch = value > (alpha + 64 + 11 * (newDepth - d));
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth + doDeeperSearch, !cutNode);
+ const bool doEvenDeeperSearch = value > alpha + 582;
+ const bool doShallowerSearch = value < bestValue + newDepth;
+
+ newDepth += doDeeperSearch - doShallowerSearch + doEvenDeeperSearch;
+
+ if (newDepth > d)
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode);
int bonus = value > alpha ? stat_bonus(newDepth)
: -stat_bonus(newDepth);
{
rm.score = value;
rm.selDepth = thisThread->selDepth;
+ rm.scoreLowerbound = value >= beta;
+ rm.scoreUpperbound = value <= alpha;
rm.pv.resize(1);
assert((ss+1)->pv);
}
}
}
- else
- ss->cutoffCnt = 0;
// If the move is worse than some previously searched move, remember it to update its stats later
// Continuation history based pruning (~2 Elo)
if ( !capture
&& bestValue > VALUE_TB_LOSS_IN_MAX_PLY
- && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold
- && (*contHist[1])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold)
+ && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < 0
+ && (*contHist[1])[pos.moved_piece(move)][to_sq(move)] < 0)
continue;
- // movecount pruning for quiet check evasions
+ // We prune after 2nd quiet check evasion where being 'in check' is implicitly checked through the counter
+ // and being a 'quiet' apart from being a tt move is assumed after an increment because captures are pushed ahead.
if ( bestValue > VALUE_TB_LOSS_IN_MAX_PLY
- && quietCheckEvasions > 1
- && !capture
- && ss->inCheck)
- continue;
+ && quietCheckEvasions > 1)
+ break;
quietCheckEvasions += !capture && ss->inCheck;
/// UCI::pv() formats PV information according to the UCI protocol. UCI requires
/// that all (if any) unsearched PV lines are sent using a previous search score.
-string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
+string UCI::pv(const Position& pos, Depth depth) {
std::stringstream ss;
TimePoint elapsed = Time.elapsed() + 1;
if (Options["UCI_ShowWDL"])
ss << UCI::wdl(v, pos.game_ply());
- if (!tb && i == pvIdx)
- ss << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : "");
+ if (i == pvIdx && !tb && updated) // tablebase- and previous-scores are exact
+ ss << (rootMoves[i].scoreLowerbound ? " lowerbound" : (rootMoves[i].scoreUpperbound ? " upperbound" : ""));
ss << " nodes " << nodesSearched
- << " nps " << nodesSearched * 1000 / elapsed;
-
- if (elapsed > 1000) // Earlier makes little sense
- ss << " hashfull " << TT.hashfull();
-
- ss << " tbhits " << tbHits
+ << " nps " << nodesSearched * 1000 / elapsed
+ << " hashfull " << TT.hashfull()
+ << " tbhits " << tbHits
<< " time " << elapsed
<< " pv";
projects / stockfish / blobdiff