From: DU-jdto <jadto@outlook.com>
Date: Wed, 13 Jun 2018 05:22:52 +0000 (+1000)
Subject: Remove lmrDepth restriction on quiet see pruning
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=a834bfe8332adcb0dfc1fd280f1f9d8bbce86266

Remove lmrDepth restriction on quiet see pruning

And tweak the threshold value. With this threshold and the current piece
values, this permits see pruning on quiets to be done up to an lmrDepth
of 9 (beyond that the threshold is below -QueenValueMg and see_ge will
pass unconditionally).

STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 110316 W: 24612 L: 24667 D: 61037
http://tests.stockfishchess.org/tests/view/5b20aa760ebc5902ab9c9c1d

LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 17352 W: 2968 L: 2842 D: 11542
http://tests.stockfishchess.org/tests/view/5b20cf1e0ebc5902ab9c9fb6

Closes https://github.com/official-stockfish/Stockfish/pull/1651

Bench: 5069074
---

diff --git a/src/search.cpp b/src/search.cpp
index c678cd53..fb5dfd00 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -947,8 +947,7 @@ moves_loop: // When in check, search starts from here
                   continue;
 
               // Prune moves with negative SEE (~10 Elo)
-              if (   lmrDepth < 8
-                  && !pos.see_ge(move, Value(-35 * lmrDepth * lmrDepth)))
+              if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth)))
                   continue;
           }
           else if (   !extension // (~20 Elo)