From bf2a0d53925da1a0d58a91ef78d577a448eb4b5a Mon Sep 17 00:00:00 2001
From: Taras Vuk <117687515+TarasVuk@users.noreply.github.com>
Date: Mon, 14 Oct 2024 21:30:18 +0200
Subject: [PATCH] Simplify internal iterative reductions

Passed STC:
LLR: 2.92 (-2.94,2.94) <-1.75,0.25>
Total: 138656 W: 36182 L: 36074 D: 66400
Ptnml(0-2): 523, 16422, 35310, 16570, 503
https://tests.stockfishchess.org/tests/view/6702beb386d5ee47d953bd41

Passed LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 680844 W: 172021 L: 172480 D: 336343
Ptnml(0-2): 492, 76259, 187419, 75720, 532
https://tests.stockfishchess.org/tests/view/67042b1f86d5ee47d953be7c

closes https://github.com/official-stockfish/Stockfish/pull/5634

Bench: 1169252
---
 src/search.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/search.cpp b/src/search.cpp
index 6e513b45..75a8c963 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -850,7 +850,7 @@ Value Search::Worker::search(
     // For cutNodes, if depth is high enough, decrease depth by 2 if there is no ttMove,
     // or by 1 if there is a ttMove with an upper bound.
     if (cutNode && depth >= 7 && (!ttData.move || ttData.bound == BOUND_UPPER))
-        depth -= 1 + !ttData.move;
+        depth -= 2;
 
     // Step 11. ProbCut (~10 Elo)
     // If we have a good enough capture (or queen promotion) and a reduced search