Set IID half way between d/2 and d-4

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 9ab8c800d8fbde01527d266b6a8fc1d0a9c314b8..ed029b4c4a08e6d15b3ef28f2b4b246b04ad74d9 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -745,7 +745,7 @@ namespace {
         && ttMove == MOVE_NONE
         && (PvNode || (!inCheck && ss->staticEval + Value(256) >= beta)))
     {
-        Depth d = (PvNode ? depth - 2 * ONE_PLY : depth - 4 * ONE_PLY);
+        Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4);
 
         ss->skipNullMove = true;
         search<PvNode ? PV : NonPV>(pos, ss, alpha, beta, d);