From 7a7c033a86be1c14817cfa1de2c85937585526b6 Mon Sep 17 00:00:00 2001
From: FauziAkram <fauzi.dabat@hotmail.com>
Date: Fri, 3 Oct 2025 01:39:39 +0300
Subject: [PATCH] Tweak Correction History Bonus Asymmetrically

Refine the correction history update by applying an asymmetric bonus based on the type of evaluation error. It differentiates between negative corrections and positive corrections.

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 165184 W: 43314 L: 42807 D: 79063
Ptnml(0-2): 551, 19391, 42261, 19778, 611
https://tests.stockfishchess.org/tests/view/68cae49902c43c969fe7f008

Passed LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 243234 W: 62765 L: 62029 D: 118440
Ptnml(0-2): 163, 25996, 68551, 26756, 151
https://tests.stockfishchess.org/tests/view/68d1c50dfa806e2e8393aa1f

closes https://github.com/official-stockfish/Stockfish/pull/6338

Bench: 2746404
---
 src/search.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/search.cpp b/src/search.cpp
index 04c04b5be..64f8ea189 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1449,9 +1449,11 @@ moves_loop:  // When in check, search starts here
         && ((bestValue < ss->staticEval && bestValue < beta)  // negative correction & no fail high
             || (bestValue > ss->staticEval && bestMove)))     // positive correction & no fail low
     {
-        auto bonus = std::clamp(int(bestValue - ss->staticEval) * depth / 8,
-                                -CORRECTION_HISTORY_LIMIT / 4, CORRECTION_HISTORY_LIMIT / 4);
-        update_correction_history(pos, ss, *this, bonus);
+        auto bonus =
+          std::clamp(int(bestValue - ss->staticEval) * depth / (8 + (bestValue > ss->staticEval)),
+                     -CORRECTION_HISTORY_LIMIT / 4, CORRECTION_HISTORY_LIMIT / 4);
+        update_correction_history(pos, ss, *this,
+                                  (1088 - 180 * (bestValue > ss->staticEval)) * bonus / 1024);
     }
 
     assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);