Use alpha instead of beta-1

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 7ff9aaa466902ae5b851ea2c225a853d8416c576..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;
         }
     }
 
@@ -1539,7 +1539,7 @@ split_point_start: // At split points actual search starts from here
   string uci_pv(const Position& pos, int depth, Value alpha, Value beta) {
 
     std::stringstream s;
-    Time::point elaspsed = Time::now() - SearchTime + 1;
+    Time::point elapsed = Time::now() - SearchTime + 1;
     size_t uciPVSize = std::min((size_t)Options["MultiPV"], RootMoves.size());
     int selDepth = 0;
 
@@ -1564,8 +1564,8 @@ split_point_start: // At split points actual search starts from here
           << " seldepth "  << selDepth
           << " score "     << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v))
           << " nodes "     << pos.nodes_searched()
-          << " nps "       << pos.nodes_searched() * 1000 / elaspsed
-          << " time "      << elaspsed
+          << " nps "       << pos.nodes_searched() * 1000 / elapsed
+          << " time "      << elapsed
           << " multipv "   << i + 1
           << " pv";