Use refinedValue in ProbCut condition

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index ec2b1c9cee1d09ce1637bd9bed7d8b7a2e65ed0a..6e440702c9d69fc4ff26efa8fa982b2a565ecc1f 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -903,9 +903,8 @@ namespace {
     }
 
     // Step 9. ProbCut (is omitted in PV nodes)
-    // If we have a very good capture (i.e. SEE > seeValues[captured_piece_type])
-    // and a reduced search returns a value much above beta, we can (almost) safely
-    // prune the previous move.
+    // If we have a good capture that raises the score well above beta and a reduced
+    // search confirms the score then we can (almost) safely prune the previous move.
     if (   !PvNode
         &&  depth >= RazorDepth + ONE_PLY
         && !inCheck
@@ -918,7 +917,7 @@ namespace {
 
         assert(rdepth >= ONE_PLY);
 
-        MovePicker mp(pos, ttMove, H, Position::see_value(pos.captured_piece_type()));
+        MovePicker mp(pos, ttMove, H, Max(rbeta - refinedValue, VALUE_ZERO));
         pinned = pos.pinned_pieces(pos.side_to_move());
 
         while ((move = mp.get_next_move()) != MOVE_NONE)