Improve multiPV mode

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 9919b0cc87405bb9e411b86aece1a373ac4eca13..37fc2ec48a8bfa99b7e4a125f68f540fe1ebaba0 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -292,7 +292,7 @@ void Thread::search() {
   bestValue = delta = alpha = -VALUE_INFINITE;
   beta = VALUE_INFINITE;
 
   bestValue = delta = alpha = -VALUE_INFINITE;
   beta = VALUE_INFINITE;
 

-  size_t multiPV = Options["MultiPV"];
+  multiPV = Options["MultiPV"];

   Skill skill(Options["Skill Level"]);
 
   // When playing with strength handicap enable MultiPV search that we will
   Skill skill(Options["Skill Level"]);
 
   // When playing with strength handicap enable MultiPV search that we will


@@ -870,6 +870,12 @@ moves_loop: // When in check, search starts from here
           sync_cout << "info depth " << depth / ONE_PLY
                     << " currmove " << UCI::move(move, pos.is_chess960())
                     << " currmovenumber " << moveCount + thisThread->pvIdx << sync_endl;
           sync_cout << "info depth " << depth / ONE_PLY
                     << " currmove " << UCI::move(move, pos.is_chess960())
                     << " currmovenumber " << moveCount + thisThread->pvIdx << sync_endl;

+
+      // In MultiPV mode also skip moves which will be searched later as PV moves
+      if (rootNode && std::count(thisThread->rootMoves.begin() + thisThread->pvIdx + 1,
+                                 thisThread->rootMoves.begin() + thisThread->multiPV, move))
+          continue;
+

       if (PvNode)
           (ss+1)->pv = nullptr;
 
       if (PvNode)
           (ss+1)->pv = nullptr;
 


@@ -913,10 +919,11 @@ moves_loop: // When in check, search starts from here
           // Multi-cut pruning
           // Our ttMove is assumed to fail high, and now we failed high also on a reduced
           // search without the ttMove. So we assume this expected Cut-node is not singular,
           // Multi-cut pruning
           // Our ttMove is assumed to fail high, and now we failed high also on a reduced
           // search without the ttMove. So we assume this expected Cut-node is not singular,

-          // that is multiple moves fail high, and we can prune the whole subtree by returning
-          // the hard beta bound.
-          else if (cutNode && singularBeta > beta)
-              return beta;
+          // that multiple moves fail high, and we can prune the whole subtree by returning
+          // a soft bound.
+          else if (   eval >= beta
+                   && singularBeta >= beta)
+              return singularBeta;

       }
 
       // Check extension (~2 Elo)
       }
 
       // Check extension (~2 Elo)