Simplify depth condition in prior reduction

daniel-monroe · vondele · commit 57d76bd459a0 · 2025-08-24T19:43:48.000+02:00
Passed simplification STC LLR: 2.94 (-2.94,2.94) <-1.75,0.25> Total: 172864 W: 45085 L: 45015 D: 82764 Ptnml(0-2): 516, 20456, 44405, 20552, 503 https://tests.stockfishchess.org/tests/view/68a24791b6fb3300203bbdb6 Passed simplification LTC LLR: 2.94 (-2.94,2.94) <-1.75,0.25> Total: 84738 W: 21733 L: 21578 D: 41427 Ptnml(0-2): 49, 9169, 23780, 9320, 51 https://tests.stockfishchess.org/tests/view/68a2665ab6fb3300203bc269 closes official-stockfish#6244 Bench: 2131292
diff --git a/src/search.cpp b/src/search.cpp
@@ -824,7 +824,7 @@ Value Search::Worker::search(
     improving         = ss->staticEval > (ss - 2)->staticEval;
     opponentWorsening = ss->staticEval > -(ss - 1)->staticEval;
 
-    if (priorReduction >= (depth < 10 ? 2 : 3) && !opponentWorsening)
+    if (priorReduction >= 3 && !opponentWorsening)
         depth++;
     if (priorReduction >= 2 && depth >= 2 && ss->staticEval + (ss - 1)->staticEval > 173)
         depth--;
