Simplify move history reduction

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index c878b0aba1dc82778f94a029ddddc89c7c984956..6580f520130f3d15b5be45edf3347289fcc568e7 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -94,10 +94,10 @@ constexpr int futility_move_count(bool improving, Depth depth) {
 }
 
 // History and stats update bonus, based on depth
-int stat_bonus(Depth d) { return std::min(364 * d - 438, 1501); }
+int stat_bonus(Depth d) { return std::min(291 * d - 350, 1200); }
 
 // History and stats update malus, based on depth
-int stat_malus(Depth d) { return std::min(452 * d - 452, 1478); }
+int stat_malus(Depth d) { return std::min(361 * d - 361, 1182); }
 
 // Add a small random component to draw evaluations to avoid 3-fold blindness
 Value value_draw(const Thread* thisThread) {
@@ -746,7 +746,7 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
     // Use static evaluation difference to improve quiet move ordering (~4 Elo)
     if (is_ok((ss - 1)->currentMove) && !(ss - 1)->inCheck && !priorCapture)
     {
-        int bonus = std::clamp(-18 * int((ss - 1)->staticEval + ss->staticEval), -1812, 1812);
+        int bonus = std::clamp(-14 * int((ss - 1)->staticEval + ss->staticEval), -1449, 1449);
         thisThread->mainHistory[~us][from_to((ss - 1)->currentMove)] << bonus;
         if (type_of(pos.piece_on(prevSq)) != PAWN && type_of((ss - 1)->currentMove) != PROMOTION)
             thisThread->pawnHistory[pawn_structure(pos)][pos.piece_on(prevSq)][prevSq] << bonus / 4;
@@ -1165,7 +1165,7 @@ moves_loop:  // When in check, search starts here
                       + (*contHist[3])[movedPiece][to_sq(move)] - 3848;
 
         // Decrease/increase reduction for moves with a good/bad history (~25 Elo)
-        r -= ss->statScore / (10216 + 3855 * (depth > 5 && depth < 23));
+        r -= ss->statScore / 14200;
 
         // Step 17. Late moves reduction / extension (LMR, ~117 Elo)
         // We use various heuristics for the sons of a node after the first son has