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;
}
}
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;
value = bestValue;
singularLMR = moveCountPruning = false;
ttCapture = ttMove && pos.capture_or_promotion(ttMove);
+ bool formerPv = ttPv && !PvNode;
// Mark this node as being searched
ThreadHolding th(thisThread, posKey, ss->ply);
&& tte->depth() >= depth - 3
&& pos.legal(move))
{
- Value singularBeta = ttValue - (((ttPv && !PvNode) + 4) * depth) / 2;
- Depth singularDepth = (depth - 1 + 3 * (ttPv && !PvNode)) / 2;
+ Value singularBeta = ttValue - ((formerPv + 4) * depth) / 2;
+ Depth singularDepth = (depth - 1 + 3 * formerPv) / 2;
ss->excludedMove = move;
value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, singularDepth, cutNode);
ss->excludedMove = MOVE_NONE;
if (ttPv)
r -= 2;
+ if (moveCountPruning && !formerPv)
+ r++;
+
// Decrease reduction if opponent's move count is high (~5 Elo)
if ((ss-1)->moveCount > 14)
r--;
// Decrease reduction if ttMove has been singularly extended (~3 Elo)
if (singularLMR)
- r -= 1 + (ttPv && !PvNode);
+ r -= 1 + formerPv;
if (!captureOrPromotion)
{