decrease if beta - alpha > 100

MJZ1977 · Apr 15, 2019 · 57835dc · 57835dc
1 parent 1594d15
commit 57835dc
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/src/search.cpp b/src/search.cpp
@@ -1006,6 +1006,10 @@ namespace {
           if (ttPv)
               r -= ONE_PLY;
 
+          // If PvNode and (beta - alpha) is too broad, decrease reduction to avoid instabilities
+          if (beta - alpha > Value(100))
+              r -= ONE_PLY;
+
           // Decrease reduction if opponent's move count is high (~10 Elo)
           if ((ss-1)->moveCount > 15)
               r -= ONE_PLY;