Use alpha instead of beta-1

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 1d81fd045d447312ad85302a4addacca087e4707..00c871fd4acb8774352a67643fffeb8f4437ba96 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -455,11 +455,11 @@ namespace {
                     || Time::now() - SearchTime > (TimeMgr.available_time() * 20) / 100))
             {
                 Value rBeta = bestValue - 2 * PawnValueMg;
-                (ss+1)->excludedMove = RootMoves[0].pv[0];
-                (ss+1)->skipNullMove = true;
-                Value v = search<NonPV>(pos, ss+1, rBeta - 1, rBeta, (depth - 3) * ONE_PLY);
-                (ss+1)->skipNullMove = false;
-                (ss+1)->excludedMove = MOVE_NONE;
+                ss->excludedMove = RootMoves[0].pv[0];
+                ss->skipNullMove = true;
+                Value v = search<NonPV>(pos, ss, rBeta - 1, rBeta, (depth - 3) * ONE_PLY);
+                ss->skipNullMove = false;
+                ss->excludedMove = MOVE_NONE;
 
                 if (v < rBeta)
                     stop = true;
@@ -716,7 +716,7 @@ namespace {
                 && (ss-1)->reduction
                 && threatMove != MOVE_NONE
                 && allows(pos, (ss-1)->currentMove, threatMove))
-                return beta - 1;
+                return alpha;
         }
     }