From: Marco Costalba <mcostalba@gmail.com>
Date: Sat, 12 Jun 2010 13:47:30 +0000 (+0100)
Subject: Extend checks only if SEE is non-negative
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=221f41c2dffd100e8069bde7785022f4366f1e70;hp=a8b9c11f5666a6298d684e21156f4ac9d89c8d8c

Extend checks only if SEE is non-negative

Idea from Dr. Hyatt

After 10k games at 5"+0 on my QUAD
Mod vs Orig +2750 =4601 -2649 +4 ELO

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

diff --git a/src/search.cpp b/src/search.cpp
index af32165c..693bea94 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1948,7 +1948,7 @@ namespace {
 
     if (*dangerous)
     {
-        if (moveIsCheck)
+        if (moveIsCheck && pos.see_sign(m)>= 0)
             result += CheckExtension[PvNode];
 
         if (singleEvasion)