- Depth r = reduction(improving, depth, moveCount, delta, thisThread->rootDelta);
-
- // Decrease reduction if position is or has been on the PV
- // and node is not likely to fail low. (~3 Elo)
- if ( ss->ttPv
- && !likelyFailLow)
- r -= 2;
-
- // Decrease reduction if opponent's move count is high (~1 Elo)
- if ((ss-1)->moveCount > 7)
- r--;
-
- // Increase reduction for cut nodes (~3 Elo)
- if (cutNode)
- r += 2;
-
- // Increase reduction if ttMove is a capture (~3 Elo)
- if (ttCapture)
- r++;
-
- // Decrease reduction for PvNodes based on depth
- if (PvNode)
- r -= 1 + 15 / (3 + depth);
-
- // Decrease reduction if ttMove has been singularly extended (~1 Elo)
- 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)
- r++;
-
- ss->statScore = 2 * thisThread->mainHistory[us][from_to(move)]
- + (*contHist[0])[movedPiece][to_sq(move)]
- + (*contHist[1])[movedPiece][to_sq(move)]
- + (*contHist[3])[movedPiece][to_sq(move)]
- - 4334;
-
- // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
- r -= ss->statScore / 15914;
-