X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=a81c85273aa4e6325e103dcd1d7ec1afc2636054;hp=59b1b1f19a84f19dccb8c58b288d53c6944ace9c;hb=f2f3a06a1acfa14b3054bfd73d6c3966c326a7cc;hpb=76971d8acba4af1896cf94e1278f69ae2084d45d

diff --git a/src/search.cpp b/src/search.cpp
index 59b1b1f1..a81c8527 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -729,7 +729,6 @@ namespace {
 
     // Step 8. Null move search with verification search (is omitted in PV nodes)
     if (   !PvNode
-        &&  depth >= 2 * ONE_PLY
         &&  eval >= beta
         && (ss->staticEval >= beta - 35 * (depth / ONE_PLY - 6) || depth >= 13 * ONE_PLY)
         &&  pos.non_pawn_material(pos.side_to_move()))
@@ -930,9 +929,16 @@ moves_loop: // When in check search starts from here
               && ss->staticEval + futility_margin(predictedDepth) + 256 <= alpha)
               continue;
 
-          // Prune moves with negative SEE at low depths
-          if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO)
-              continue;
+          // Prune moves with negative SEE at low depths and below a decreasing
+          // threshold at higher depths.
+          if (predictedDepth < 8 * ONE_PLY)
+          {
+              Value see_v = predictedDepth < 4 * ONE_PLY ? VALUE_ZERO
+                            : -PawnValueMg * 2 * int(predictedDepth - 3 * ONE_PLY);
+
+              if (pos.see_sign(move) < see_v)
+                  continue;
+          }
       }
 
       // Speculative prefetch as early as possible