Simplify futility margin in lmr for quiets.

daniel-monroe · vondele · commit 27e747d1d727 · 2025-01-25T20:59:33.000+01:00
Replace the "low bestValue condition" with whether there is a best move. Passed Simplification STC LLR: 2.95 (-2.94,2.94) <-1.75,0.25> Total: 102560 W: 26517 L: 26367 D: 49676 Ptnml(0-2): 328, 12223, 26036, 12357, 336 https://tests.stockfishchess.org/tests/view/679310e4ca18a2c66da02af8 Passed Simplification LTC LLR: 2.95 (-2.94,2.94) <-1.75,0.25> Total: 66942 W: 17130 L: 16953 D: 32859 Ptnml(0-2): 52, 7459, 18290, 7600, 70 https://tests.stockfishchess.org/tests/view/679459a3e96bfb672ad18ddf closes #5820 Bench: 1438043
diff --git a/src/search.cpp b/src/search.cpp
@@ -1028,8 +1028,7 @@ Value Search::Worker::search(
 
                 lmrDepth += history / 3459;
 
-                Value futilityValue =
-                  ss->staticEval + (bestValue < ss->staticEval - 47 ? 137 : 47) + 142 * lmrDepth;
+                Value futilityValue = ss->staticEval + (bestMove ? 47 : 137) + 142 * lmrDepth;
 
                 // Futility pruning: parent node
                 if (!ss->inCheck && lmrDepth < 12 && futilityValue <= alpha)
