From 57d76bd459a0c29f0932112d1ee432592054e1ce Mon Sep 17 00:00:00 2001
From: Daniel Monroe <github.com@danielmonroe.net>
Date: Sun, 17 Aug 2025 17:20:08 -0400
Subject: [PATCH] Simplify depth condition in prior reduction

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 https://github.com/official-stockfish/Stockfish/pull/6244

Bench: 2131292
---
 src/search.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/search.cpp b/src/search.cpp
index 7068c332d..f5fad184a 100644
--- 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--;