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 af32165..693bea9 100644 (file)
--- 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)