X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=056dc250377a9ecf8ae63ab3270247f3cc331da3;hb=e88ef801af3ac5400c1b82d009666fb082c24a16;hp=93867f0f0b20859f97598d094a54dedbb0d5f171;hpb=074c7a3c30dce46b65bc7deb15619a6a33ecf4a8;p=stockfish

diff --git a/src/search.cpp b/src/search.cpp
index 93867f0f..056dc250 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -600,11 +600,9 @@ namespace {
         &&  abs(beta) < VALUE_MATE_IN_MAX_PLY
         && !pos.pawn_on_7th(pos.side_to_move()))
     {
-        Value rbeta = beta - razor_margin(depth);
-        Value v = qsearch<NonPV, false>(pos, ss, rbeta-1, rbeta, DEPTH_ZERO);
-        if (v < rbeta)
-            // Logically we should return (v + razor_margin(depth)), but
-            // surprisingly this performed slightly weaker in tests.
+        Value ralpha = alpha - razor_margin(depth);
+        Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1, DEPTH_ZERO);
+        if (v <= ralpha)
             return v;
     }
 
@@ -632,7 +630,7 @@ namespace {
 
         // Null move dynamic reduction based on depth and value
         Depth R =  3 * ONE_PLY
-                 + depth / (2 * ONE_PLY)
+                 + depth / 4
                  + int(eval - beta) / PawnValueMg * ONE_PLY;
 
         pos.do_null_move(st);