void Search::init() {
for (int i = 1; i < MAX_MOVES; ++i)
- Reductions[i] = int((24.8 + std::log(Threads.size()) / 2) * std::log(i));
+ Reductions[i] = int((24.8 + std::log(Threads.size())) * std::log(i));
}
std::map<Move, int64_t> votes;
Value minScore = this->rootMoves[0].score;
- // Find out minimum score
+ // Find minimum score
for (Thread* th: Threads)
minScore = std::min(minScore, th->rootMoves[0].score);
votes[th->rootMoves[0].pv[0]] +=
(th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
- if (bestThread->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY)
+ if (abs(bestThread->rootMoves[0].score) >= VALUE_TB_WIN_IN_MAX_PLY)
{
- // Make sure we pick the shortest mate
+ // Make sure we pick the shortest mate / TB conversion or stave off mate the longest
if (th->rootMoves[0].score > bestThread->rootMoves[0].score)
bestThread = th;
}
else if ( th->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY
- || votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]])
+ || ( th->rootMoves[0].score > VALUE_TB_LOSS_IN_MAX_PLY
+ && votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]]))
bestThread = th;
}
}
}
}
+ CapturePieceToHistory& captureHistory = thisThread->captureHistory;
+
// Step 6. Static evaluation of the position
if (inCheck)
{
if (nullValue >= beta)
{
- // Do not return unproven mate scores
+ // Do not return unproven mate or TB scores
if (nullValue >= VALUE_TB_WIN_IN_MAX_PLY)
nullValue = beta;
&& abs(beta) < VALUE_TB_WIN_IN_MAX_PLY)
{
Value raisedBeta = std::min(beta + 189 - 45 * improving, VALUE_INFINITE);
- MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &thisThread->captureHistory);
+ MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &captureHistory);
int probCutCount = 0;
while ( (move = mp.next_move()) != MOVE_NONE
MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
&thisThread->lowPlyHistory,
- &thisThread->captureHistory,
+ &captureHistory,
contHist,
countermove,
ss->killers,
// Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
moveCountPruning = moveCount >= futility_move_count(improving, depth);
+ // Reduced depth of the next LMR search
+ int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
+
if ( !captureOrPromotion
&& !givesCheck)
{
- // Reduced depth of the next LMR search
- int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
-
// Countermoves based pruning (~20 Elo)
if ( lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
&& (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold
if (!pos.see_ge(move, Value(-(32 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
continue;
}
- else if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo)
- continue;
+ else
+ {
+ if ( !givesCheck
+ && lmrDepth < 1
+ && captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] < 0)
+ continue;
+
+ if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo)
+ continue;
+ }
}
// Step 14. Extensions (~75 Elo)
// Decrease/increase reduction for moves with a good/bad history (~30 Elo)
r -= ss->statScore / 16434;
}
-
- // Increase reduction for captures/promotions if late move and at low depth
- else if (depth < 8 && moveCount > 2)
- r++;
+ else
+ {
+ // Increase reduction for captures/promotions if late move and at low depth
+ if (depth < 8 && moveCount > 2)
+ r++;
+
+ // Unless giving check, this capture is likely bad
+ if ( !givesCheck
+ && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 200 * depth <= alpha)
+ r++;
+ }
Depth d = Utility::clamp(newDepth - r, 1, newDepth);