Razor more if ss+1 cutoffCnt > 3

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index f49c23aed6571dcc8a6d024f3f2b813fb08a3290..a5b5c101e695c41abc0c9dd3b82c2a6b4860441c 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -766,7 +766,8 @@ namespace {
     // Step 7. Razoring (~1 Elo)
     // If eval is really low check with qsearch if it can exceed alpha, if it can't,
     // return a fail low.
-    if (eval < alpha - 456 - 252 * depth * depth)
+    // Adjust razor margin according to cutoffCnt. (~1 Elo)
+    if (eval < alpha - 456 - (252 - 200 * ((ss+1)->cutoffCnt > 3)) * depth * depth)
     {
         value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
         if (value < alpha)