X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=a739b0491c7a9eae9219ba7e404c83483d04c692;hp=6aa1081f435e0cd666dc8ba3ba0dfcfdc2ebb245;hb=8e9d4081ee9def12f50dbd3169b765839fcb4c86;hpb=4630ab574333be3cfabb6fcf3eca6d66ae961fe1

diff --git a/src/search.cpp b/src/search.cpp
index 6aa1081f..a739b049 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -933,6 +933,13 @@ moves_loop: // When in check and at SpNode search starts from here
 
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
 
+          // Research at intermediate depth if reduction is very high
+          if (value > alpha && ss->reduction >= 4 * ONE_PLY)
+          {
+              Depth d2 = std::max(newDepth - 2 * ONE_PLY, ONE_PLY);
+              value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d2, true);
+          }
+
           doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
           ss->reduction = DEPTH_ZERO;
       }