diff --git a/src/search.cpp b/src/search.cpp index ffa37ab623a..3c630db0b8a 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -944,11 +944,6 @@ Value Search::Worker::search( value = bestValue; moveCountPruning = singularQuietLMR = false; - // Indicate PvNodes that will probably fail low if the node was searched - // at a depth equal to or greater than the current depth, and the result - // of this search was a fail low. - bool likelyFailLow = PvNode && ttMove && (tte->bound() & BOUND_UPPER) && tte->depth() >= depth; - // Step 13. Loop through all pseudo-legal moves until no moves remain // or a beta cutoff occurs. while ((move = mp.next_move(moveCountPruning)) != Move::none()) @@ -1153,9 +1148,10 @@ Value Search::Worker::search( thisThread->nodes.fetch_add(1, std::memory_order_relaxed); pos.do_move(move, st, givesCheck); - // Decrease reduction if position is or has been on the PV (~4 Elo) - if (ss->ttPv && !likelyFailLow) - r -= 1 + (cutNode && tte->depth() >= depth) + (ttValue > alpha); + // Decrease reduction if position is or has been on the PV (~7 Elo) + if (ss->ttPv) + r -= !(tte->bound() == BOUND_UPPER && PvNode) + (cutNode && tte->depth() >= depth) + + (ttValue > alpha) + (ttValue > beta && tte->depth() >= depth); // Decrease reduction if opponent's move count is high (~1 Elo) if ((ss - 1)->moveCount > 7)