X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=93867f0f0b20859f97598d094a54dedbb0d5f171;hp=d59fc521eedcba2815ae3cdeaf92f4bdb6e80730;hb=074c7a3c30dce46b65bc7deb15619a6a33ecf4a8;hpb=cf95a55d763b0746b455b6ba659720aa1dd64028

diff --git a/src/search.cpp b/src/search.cpp
index d59fc521..93867f0f 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -628,12 +628,12 @@ namespace {
     {
         ss->currentMove = MOVE_NULL;
 
-        // Null move dynamic reduction based on depth
-        Depth R = 3 * ONE_PLY + depth / 4;
+        assert(eval - beta >= 0);
 
-        // Null move dynamic reduction based on value
-        if (eval - PawnValueMg > beta)
-            R += ONE_PLY;
+        // Null move dynamic reduction based on depth and value
+        Depth R =  3 * ONE_PLY
+                 + depth / (2 * ONE_PLY)
+                 + int(eval - beta) / PawnValueMg * ONE_PLY;
 
         pos.do_null_move(st);
         (ss+1)->skipNullMove = true;
@@ -653,7 +653,8 @@ namespace {
 
             // Do verification search at high depths
             ss->skipNullMove = true;
-            Value v = search<NonPV>(pos, ss, alpha, beta, depth-R, false);
+            Value v = depth-R < ONE_PLY ? qsearch<NonPV, false>(pos, ss, alpha, beta, DEPTH_ZERO)
+                                        :  search<NonPV>(pos, ss, alpha, beta, depth-R, false);
             ss->skipNullMove = false;
 
             if (v >= beta)