From: Marco Costalba <mcostalba@gmail.com>
Date: Tue, 22 Feb 2011 22:23:45 +0000 (+0100)
Subject: Prune moves with equal SEE in qsearch
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=91a27663084ea9be4918ba028aa2b151bc0f4e1c;ds=sidebyside

Prune moves with equal SEE in qsearch

After 5166 games:
Mod vs Orig 890 - 762 - 3514  ELO +8 (+- 5.5) LOS 96%

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---

diff --git a/src/search.cpp b/src/search.cpp
index b1a720d7..31522607 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1427,6 +1427,13 @@ split_point_start: // At split points actual search starts from here
                   bestValue = futilityValue;
               continue;
           }
+
+          // Prune moves with negative or equal SEE
+          if (   futilityBase < beta
+              && depth < DEPTH_ZERO
+              && bestValue > value_mated_in(PLY_MAX)
+              && pos.see(move) <= 0)
+              continue;
       }
 
       // Detect non-capture evasions that are candidate to be pruned