Tweaking the futility pruning formula

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index aaf545d26580c0d42f852242677bb34483d13cc9..27f0f9870852c1dd691fc67f6dfd8679ee34274b 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -745,6 +745,8 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
     {
         int bonus = std::clamp(-18 * int((ss - 1)->staticEval + ss->staticEval), -1812, 1812);
         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;
     }
 
     // Set up the improving flag, which is true if current static evaluation is
@@ -1007,7 +1009,10 @@ moves_loop:  // When in check, search starts here
                 lmrDepth = std::max(lmrDepth, -1);
 
                 // Futility pruning: parent node (~13 Elo)
-                if (!ss->inCheck && lmrDepth < 13 && ss->staticEval + 77 + 124 * lmrDepth <= alpha)
+                if (!ss->inCheck && lmrDepth < 13
+                    && ss->staticEval + (bestValue < ss->staticEval - 62 ? 123 : 77)
+                           + 127 * lmrDepth
+                         <= alpha)
                     continue;
 
                 lmrDepth = std::max(lmrDepth, 0);