From: Michael Chaly <Vizvezdenec@gmail.com>
Date: Sat, 27 Nov 2021 13:38:37 +0000 (+0300)
Subject: Adjust usage of history in futility pruning
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=8bb5a436b240d22e3e9729a1cd094169941afd7c

Adjust usage of history in futility pruning

This patch refines 0ac8aca893dd2052f8433e0b4a3d65073266b00f that uses history heuristics in futility pruning.
Now it adds main history of the move to in and also increases effect by factor of 2.

passed STC
https://tests.stockfishchess.org/tests/view/61a156829e83391467a2b2c9
LLR: 2.94 (-2.94,2.94) <0.00,2.50>
Total: 68464 W: 17920 L: 17587 D: 32957
Ptnml(0-2): 239, 7711, 18025, 7992, 265

passed LTC
https://tests.stockfishchess.org/tests/view/61a1bde99e83391467a2b305
LLR: 2.95 (-2.94,2.94) <0.50,3.00>
Total: 26088 W: 6926 L: 6674 D: 12488
Ptnml(0-2): 18, 2619, 7531, 2845, 31

closes https://github.com/official-stockfish/Stockfish/pull/3812

bench 6804653
---

diff --git a/src/search.cpp b/src/search.cpp
index 12c89de4..8f9fa62c 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1063,10 +1063,12 @@ moves_loop: // When in check, search starts here
                   && history < -3000 * depth + 3000)
                   continue;
 
+              history += thisThread->mainHistory[us][from_to(move)];                  
+
               // Futility pruning: parent node (~5 Elo)
               if (   !ss->inCheck
                   && lmrDepth < 8
-                  && ss->staticEval + 172 + 145 * lmrDepth + history / 256 <= alpha)
+                  && ss->staticEval + 172 + 145 * lmrDepth + history / 128 <= alpha)
                   continue;
 
               // Prune moves with negative SEE (~20 Elo)