diff --git a/src/search.cpp b/src/search.cpp index 2abfbaf2..8a4db351 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -69,9 +69,9 @@ namespace { // Reductions lookup table, initialized at startup int Reductions[MAX_MOVES]; // [depth or moveNumber] - Depth reduction(bool i, Depth d, int mn, bool rangeReduction) { + Depth reduction(bool i, Depth d, int mn, bool rangeReduction, Value delta, Value rootDelta) { int r = Reductions[d] * Reductions[mn]; - return (r + 534) / 1024 + (!i && r > 904) + rangeReduction; + return (r + 1358 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 904) + rangeReduction; } constexpr int futility_move_count(bool improving, Depth depth) { @@ -1015,6 +1015,8 @@ moves_loop: // When in check, search starts here // Calculate new depth for this move newDepth = depth - 1; + Value delta = beta - alpha; + // Step 13. Pruning at shallow depth (~200 Elo). Depth conditions are important for mate finding. if ( !rootNode && pos.non_pawn_material(us) @@ -1024,7 +1026,7 @@ moves_loop: // When in check, search starts here moveCountPruning = moveCount >= futility_move_count(improving, depth); // Reduced depth of the next LMR search - int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount, rangeReduction > 2), 0); + int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount, rangeReduction > 2, delta, thisThread->rootDelta), 0); if ( captureOrPromotion || givesCheck) @@ -1052,8 +1054,6 @@ moves_loop: // When in check, search starts here history += thisThread->mainHistory[us][from_to(move)]; - lmrDepth = std::max(0, lmrDepth - (beta - alpha < thisThread->rootDelta / 4)); - // Futility pruning: parent node (~5 Elo) if ( !ss->inCheck && lmrDepth < 8 @@ -1161,12 +1161,11 @@ moves_loop: // When in check, search starts here || !captureOrPromotion || (cutNode && (ss-1)->moveCount > 1))) { - Depth r = reduction(improving, depth, moveCount, rangeReduction > 2); + Depth r = reduction(improving, depth, moveCount, rangeReduction > 2, delta, thisThread->rootDelta); // Decrease reduction at some PvNodes (~2 Elo) if ( PvNode - && bestMoveCount <= 3 - && beta - alpha >= thisThread->rootDelta / 4) + && bestMoveCount <= 3) r--; // Decrease reduction if position is or has been on the PV @@ -1175,10 +1174,6 @@ moves_loop: // When in check, search starts here && !likelyFailLow) r -= 2; - // Increase reduction at non-PV nodes (~3 Elo) - if (!PvNode) - r++; - // Decrease reduction if opponent's move count is high (~1 Elo) if ((ss-1)->moveCount > 13) r--;