From e2be0aaf67569788f0d1e726d0a86ce1604958da Mon Sep 17 00:00:00 2001
From: FauziAkram <fauzi.dabat@hotmail.com>
Date: Thu, 6 Jun 2024 13:07:45 +0300
Subject: [PATCH] Tweak pruning formula

Tweak pruning formula, including a constant. I started from an old
yellow patch, if I'm not mistaken by Viz (Unfortunately I lost the link)
where he tried something similar.
I worked on it, trying different variations, until I came up with a good
configuration to pass.

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 213120 W: 55351 L: 54778 D: 102991
Ptnml(0-2): 572, 25209, 54437, 25758, 584
https://tests.stockfishchess.org/tests/view/6660c9a7c340c8eed7758195

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 315324 W: 80176 L: 79284 D: 155864
Ptnml(0-2): 155, 34711, 87030, 35619, 147
https://tests.stockfishchess.org/tests/view/6660d7bb6489614cdad13d66

closes https://github.com/official-stockfish/Stockfish/pull/5370

Bench: 1231853
---
 src/search.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/search.cpp b/src/search.cpp
index e0a49dba..7417a4b6 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1580,7 +1580,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
 
                 // If static exchange evaluation is much worse than what is needed to not
                 // fall below alpha we can prune this move.
-                if (futilityBase > alpha && !pos.see_ge(move, (alpha - futilityBase) * 4))
+                if (futilityBase > alpha && !pos.see_ge(move, (alpha - futilityBase) * 2 - 30))
                 {
                     bestValue = alpha;
                     continue;