From: Ralph Stößer <ralph.stoesser@ralph_stoesser.(none)>
Date: Mon, 23 Sep 2013 06:03:12 +0000 (+0200)
Subject: Reduce negative quiets by ONE_PLY / 2
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=d7f5f15d69564ef8399235e0c24806fdf84413f1

Reduce negative quiets by ONE_PLY / 2

Passed both short TC:
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 3402 W: 708 L: 593 D: 2101

And long TC:
LLR: 2.93 (-2.94,2.94) [0.00,6.00]
Total: 23379 W: 3972 L: 3759 D: 15648

bench: 3529630
---

diff --git a/src/search.cpp b/src/search.cpp
index 4ab17fd8..63c9e076 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -949,8 +949,11 @@ moves_loop: // When in check and at SpNode search starts from here
           if (!PvNode && cutNode)
               ss->reduction += ONE_PLY;
 
+          else if (History[pos.piece_on(to_sq(move))][to_sq(move)] < 0)
+              ss->reduction += ONE_PLY / 2;
+
           if (move == countermoves[0] || move == countermoves[1])
-              ss->reduction = std::max(DEPTH_ZERO, ss->reduction-ONE_PLY);
+              ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
 
           Depth d = std::max(newDepth - ss->reduction, ONE_PLY);
           if (SpNode)