assert(eval - beta >= 0);
// Null move dynamic reduction based on depth and value
- Depth R = (1090 + 81 * depth) / 256 + std::min(int(eval - beta) / 205, 3);
+ Depth R = std::min(int(eval - beta) / 205, 3) + depth / 3 + 4;
ss->currentMove = MOVE_NULL;
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
else
{
// Continuation history based pruning (~20 Elo)
- if ( lmrDepth < 5
- && (*contHist[0])[movedPiece][to_sq(move)] < 23 - 23 * depth * depth
- && (*contHist[1])[movedPiece][to_sq(move)] < 23 - 23 * depth * depth)
+ if (lmrDepth < 5
+ && (*contHist[0])[movedPiece][to_sq(move)]
+ + (*contHist[1])[movedPiece][to_sq(move)]
+ + (*contHist[3])[movedPiece][to_sq(move)] < -3000 * depth + 3000)
continue;
// Futility pruning: parent node (~5 Elo)
return beta;
}
}
+
+ // Capture extensions for PvNodes and cutNodes
+ else if ( (PvNode || cutNode)
+ && captureOrPromotion
+ && moveCount != 1)
+ extension = 1;
+
+ // Check extensions
else if ( givesCheck
&& depth > 6
&& abs(ss->staticEval) > Value(100))
// In general we want to cap the LMR depth search at newDepth. But if
// reductions are really negative and movecount is low, we allow this move
- // to be searched deeper than the first move, unless ttMove was extended by 2.
- Depth d = std::clamp(newDepth - r, 1, newDepth + (r < -1 && moveCount <= 5 && !doubleExtension));
+ // to be searched deeper than the first move in specific cases.
+ Depth d = std::clamp(newDepth - r, 1, newDepth + (r < -1 && (moveCount <= 5 || (depth > 6 && PvNode)) && !doubleExtension));
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
// Bonus for prior countermove that caused the fail low
else if ( (depth >= 3 || PvNode)
&& !priorCapture)
- update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth));
+ update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + (PvNode || cutNode)));
if (PvNode)
bestValue = std::min(bestValue, maxValue);