Update parametes in classical evaluation.

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index cae8a6845626e7db07a3bd82a08332eac6322a04..e6e53e7c59d147d16aaa588670dd989f7ad66f76 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -597,7 +597,7 @@ namespace {
     Move ttMove, move, excludedMove, bestMove;
     Depth extension, newDepth;
     Value bestValue, value, ttValue, eval, maxValue, probCutBeta;
     Move ttMove, move, excludedMove, bestMove;
     Depth extension, newDepth;
     Value bestValue, value, ttValue, eval, maxValue, probCutBeta;

-    bool ttHit, ttPv, formerPv, givesCheck, improving, didLMR, priorCapture;
+    bool ttHit, formerPv, givesCheck, improving, didLMR, priorCapture;

     bool captureOrPromotion, doFullDepthSearch, moveCountPruning,
          ttCapture, singularQuietLMR;
     Piece movedPiece;
     bool captureOrPromotion, doFullDepthSearch, moveCountPruning,
          ttCapture, singularQuietLMR;
     Piece movedPiece;


@@ -644,6 +644,7 @@ namespace {
     assert(0 <= ss->ply && ss->ply < MAX_PLY);
 
     (ss+1)->ply = ss->ply + 1;
     assert(0 <= ss->ply && ss->ply < MAX_PLY);
 
     (ss+1)->ply = ss->ply + 1;

+    (ss+1)->ttPv = false;

     (ss+1)->excludedMove = bestMove = MOVE_NONE;
     (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
     Square prevSq = to_sq((ss-1)->currentMove);
     (ss+1)->excludedMove = bestMove = MOVE_NONE;
     (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
     Square prevSq = to_sq((ss-1)->currentMove);


@@ -667,10 +668,11 @@ namespace {
     ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
     ttMove =  rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0]
             : ttHit    ? tte->move() : MOVE_NONE;
     ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
     ttMove =  rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0]
             : ttHit    ? tte->move() : MOVE_NONE;

-    ttPv = PvNode || (ttHit && tte->is_pv());
-    formerPv = ttPv && !PvNode;
+    if (!excludedMove)
+        ss->ttPv = PvNode || (ttHit && tte->is_pv());
+    formerPv = ss->ttPv && !PvNode;

 
 

-    if (   ttPv
+    if (   ss->ttPv

         && depth > 12
         && ss->ply - 1 < MAX_LPH
         && !priorCapture
         && depth > 12
         && ss->ply - 1 < MAX_LPH
         && !priorCapture


@@ -748,7 +750,7 @@ namespace {
                 if (    b == BOUND_EXACT
                     || (b == BOUND_LOWER ? value >= beta : value <= alpha))
                 {
                 if (    b == BOUND_EXACT
                     || (b == BOUND_LOWER ? value >= beta : value <= alpha))
                 {

-                    tte->save(posKey, value_to_tt(value, ss->ply), ttPv, b,
+                    tte->save(posKey, value_to_tt(value, ss->ply), ss->ttPv, b,

                               std::min(MAX_PLY - 1, depth + 6),
                               MOVE_NONE, VALUE_NONE);
 
                               std::min(MAX_PLY - 1, depth + 6),
                               MOVE_NONE, VALUE_NONE);
 


@@ -798,7 +800,7 @@ namespace {
         else
             ss->staticEval = eval = -(ss-1)->staticEval + 2 * Tempo;
 
         else
             ss->staticEval = eval = -(ss-1)->staticEval + 2 * Tempo;
 

-        tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
+        tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);

     }
 
     // Step 7. Razoring (~1 Elo)
     }
 
     // Step 7. Razoring (~1 Elo)


@@ -824,7 +826,7 @@ namespace {
         && (ss-1)->statScore < 22977
         &&  eval >= beta
         &&  eval >= ss->staticEval
         && (ss-1)->statScore < 22977
         &&  eval >= beta
         &&  eval >= ss->staticEval

-        &&  ss->staticEval >= beta - 30 * depth - 28 * improving + 84 * ttPv + 182
+        &&  ss->staticEval >= beta - 30 * depth - 28 * improving + 84 * ss->ttPv + 182

         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))


@@ -898,6 +900,8 @@ namespace {
         assert(probCutBeta < VALUE_INFINITE);
         MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory);
         int probCutCount = 0;
         assert(probCutBeta < VALUE_INFINITE);
         MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory);
         int probCutCount = 0;

+        bool ttPv = ss->ttPv;
+        ss->ttPv = false;

 
         while (   (move = mp.next_move()) != MOVE_NONE
                && probCutCount < 2 + 2 * cutNode)
 
         while (   (move = mp.next_move()) != MOVE_NONE
                && probCutCount < 2 + 2 * cutNode)


@@ -938,8 +942,15 @@ namespace {
                     return value;
                 }
             }
                     return value;
                 }
             }

+         ss->ttPv = ttPv;

     }
 
     }
 

+    // Step 11. If the position is not in TT, decrease depth by 2
+    if (   PvNode
+        && depth >= 6
+        && !ttMove)
+        depth -= 2;
+

 moves_loop: // When in check, search starts from here
 
     const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
 moves_loop: // When in check, search starts from here
 
     const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,


@@ -963,7 +974,7 @@ moves_loop: // When in check, search starts from here
     // Mark this node as being searched
     ThreadHolding th(thisThread, posKey, ss->ply);
 
     // Mark this node as being searched
     ThreadHolding th(thisThread, posKey, ss->ply);
 

-    // Step 11. Loop through all pseudo-legal moves until no moves remain
+    // Step 12. Loop through all pseudo-legal moves until no moves remain

     // or a beta cutoff occurs.
     while ((move = mp.next_move(moveCountPruning)) != MOVE_NONE)
     {
     // or a beta cutoff occurs.
     while ((move = mp.next_move(moveCountPruning)) != MOVE_NONE)
     {


@@ -1001,7 +1012,7 @@ moves_loop: // When in check, search starts from here
       // Calculate new depth for this move
       newDepth = depth - 1;
 
       // Calculate new depth for this move
       newDepth = depth - 1;
 

-      // Step 12. Pruning at shallow depth (~200 Elo)
+      // Step 13. Pruning at shallow depth (~200 Elo)

       if (  !rootNode
           && pos.non_pawn_material(us)
           && bestValue > VALUE_TB_LOSS_IN_MAX_PLY)
       if (  !rootNode
           && pos.non_pawn_material(us)
           && bestValue > VALUE_TB_LOSS_IN_MAX_PLY)


@@ -1059,7 +1070,7 @@ moves_loop: // When in check, search starts from here
           }
       }
 
           }
       }
 

-      // Step 13. Extensions (~75 Elo)
+      // Step 14. Extensions (~75 Elo)

 
       // Singular extension search (~70 Elo). If all moves but one fail low on a
       // search of (alpha-s, beta-s), and just one fails high on (alpha, beta),
 
       // Singular extension search (~70 Elo). If all moves but one fail low on a
       // search of (alpha-s, beta-s), and just one fails high on (alpha, beta),


@@ -1142,10 +1153,10 @@ moves_loop: // When in check, search starts from here
                                                                 [movedPiece]
                                                                 [to_sq(move)];
 
                                                                 [movedPiece]
                                                                 [to_sq(move)];
 

-      // Step 14. Make the move
+      // Step 15. Make the move

       pos.do_move(move, st, givesCheck);
 
       pos.do_move(move, st, givesCheck);
 

-      // Step 15. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be
+      // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be

       // re-searched at full depth.
       if (    depth >= 3
           &&  moveCount > 1 + 2 * rootNode + 2 * (PvNode && abs(bestValue) < 2)
       // re-searched at full depth.
       if (    depth >= 3
           &&  moveCount > 1 + 2 * rootNode + 2 * (PvNode && abs(bestValue) < 2)


@@ -1174,7 +1185,7 @@ moves_loop: // When in check, search starts from here
               r++;
 
           // Decrease reduction if position is or has been on the PV (~10 Elo)
               r++;
 
           // Decrease reduction if position is or has been on the PV (~10 Elo)

-          if (ttPv)
+          if (ss->ttPv)

               r -= 2;
 
           if (moveCountPruning && !formerPv)
               r -= 2;
 
           if (moveCountPruning && !formerPv)


@@ -1203,7 +1214,7 @@ moves_loop: // When in check, search starts from here
               // hence break make_move(). (~2 Elo)
               else if (    type_of(move) == NORMAL
                        && !pos.see_ge(reverse_move(move)))
               // hence break make_move(). (~2 Elo)
               else if (    type_of(move) == NORMAL
                        && !pos.see_ge(reverse_move(move)))

-                  r -= 2 + ttPv - (type_of(movedPiece) == PAWN);
+                  r -= 2 + ss->ttPv - (type_of(movedPiece) == PAWN);

 
               ss->statScore =  thisThread->mainHistory[us][from_to(move)]
                              + (*contHist[0])[movedPiece][to_sq(move)]
 
               ss->statScore =  thisThread->mainHistory[us][from_to(move)]
                              + (*contHist[0])[movedPiece][to_sq(move)]


@@ -1248,7 +1259,7 @@ moves_loop: // When in check, search starts from here
           didLMR = false;
       }
 
           didLMR = false;
       }
 

-      // Step 16. Full depth search when LMR is skipped or fails high
+      // Step 17. Full depth search when LMR is skipped or fails high

       if (doFullDepthSearch)
       {
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode);
       if (doFullDepthSearch)
       {
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode);


@@ -1276,12 +1287,12 @@ moves_loop: // When in check, search starts from here
           value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false);
       }
 
           value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false);
       }
 

-      // Step 17. Undo move
+      // Step 18. Undo move

       pos.undo_move(move);
 
       assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
 
       pos.undo_move(move);
 
       assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
 

-      // Step 18. Check for a new best move
+      // Step 19. Check for a new best move

       // Finished searching the move. If a stop occurred, the return value of
       // the search cannot be trusted, and we return immediately without
       // updating best move, PV and TT.
       // Finished searching the move. If a stop occurred, the return value of
       // the search cannot be trusted, and we return immediately without
       // updating best move, PV and TT.


@@ -1358,7 +1369,7 @@ moves_loop: // When in check, search starts from here
         return VALUE_DRAW;
     */
 
         return VALUE_DRAW;
     */
 

-    // Step 19. Check for mate and stalemate
+    // Step 20. Check for mate and stalemate

     // All legal moves have been searched and if there are no legal moves, it
     // must be a mate or a stalemate. If we are in a singular extension search then
     // return a fail low score.
     // All legal moves have been searched and if there are no legal moves, it
     // must be a mate or a stalemate. If we are in a singular extension search then
     // return a fail low score.


@@ -1381,8 +1392,17 @@ moves_loop: // When in check, search starts from here
     if (PvNode)
         bestValue = std::min(bestValue, maxValue);
 
     if (PvNode)
         bestValue = std::min(bestValue, maxValue);
 

+    // If no good move is found and the previous position was ttPv, then the previous
+    // opponent move is probably good and the new position is added to the search tree.
+    if (bestValue <= alpha)
+        ss->ttPv = ss->ttPv || ((ss-1)->ttPv && depth > 3);
+    // Otherwise, a counter move has been found and if the position is the last leaf
+    // in the search tree, remove the position from the search tree.
+    else if (depth > 3)
+        ss->ttPv = ss->ttPv && (ss+1)->ttPv;
+

     if (!excludedMove && !(rootNode && thisThread->pvIdx))
     if (!excludedMove && !(rootNode && thisThread->pvIdx))

-        tte->save(posKey, value_to_tt(bestValue, ss->ply), ttPv,
+        tte->save(posKey, value_to_tt(bestValue, ss->ply), ss->ttPv,

                   bestValue >= beta ? BOUND_LOWER :
                   PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
                   depth, bestMove, ss->staticEval);
                   bestValue >= beta ? BOUND_LOWER :
                   PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
                   depth, bestMove, ss->staticEval);


@@ -1565,7 +1585,7 @@ moves_loop: // When in check, search starts from here
                                                                 [to_sq(move)];
 
       if (  !captureOrPromotion
                                                                 [to_sq(move)];
 
       if (  !captureOrPromotion

-          && moveCount >= abs(depth) + 1
+          && moveCount

           && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold
           && (*contHist[1])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold)
           continue;
           && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold
           && (*contHist[1])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold)
           continue;