Improve handling of queen imbalance

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index dbb725d4dbf558639b2ce9daf80532d992681e74..b34d82f66d42d8d24446502a8b7125ad27cf1c76 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -310,13 +310,15 @@ namespace {
 
         if (Pt == BISHOP || Pt == KNIGHT)
         {
-            // Bonus if piece is on an outpost square or can reach one
+            // Bonus if the piece is on an outpost square or can reach one
+            // Reduced bonus for knights (BadOutpost) if few relevant targets
             bb = OutpostRanks & attackedBy[Us][PAWN] & ~pe->pawn_attacks_span(Them);
+            Bitboard targets = pos.pieces(Them) & ~pos.pieces(PAWN);
+
             if (   Pt == KNIGHT
-                && bb & s & ~CenterFiles
-                && !(b & pos.pieces(Them) & ~pos.pieces(PAWN))
-                && !conditional_more_than_two(
-                      pos.pieces(Them) & ~pos.pieces(PAWN) & (s & QueenSide ? QueenSide : KingSide)))
+                && bb & s & ~CenterFiles // on a side outpost
+                && !(b & targets)        // no relevant attacks
+                && (!more_than_one(targets & (s & QueenSide ? QueenSide : KingSide))))
                 score += BadOutpost;
             else if (bb & s)
                 score += Outpost[Pt == BISHOP];
@@ -577,17 +579,21 @@ namespace {
     // Bonus for threats on the next moves against enemy queen
     if (pos.count<QUEEN>(Them) == 1)
     {
+        bool queenImbalance = pos.count<QUEEN>() == 1;
+
         Square s = pos.square<QUEEN>(Them);
-        safe = mobilityArea[Us] & ~stronglyProtected;
+        safe =   mobilityArea[Us]
+              & ~pos.pieces(Us, PAWN)
+              & ~stronglyProtected;
 
         b = attackedBy[Us][KNIGHT] & attacks_bb<KNIGHT>(s);
 
-        score += KnightOnQueen * popcount(b & safe);
+        score += KnightOnQueen * popcount(b & safe) * (1 + queenImbalance);
 
         b =  (attackedBy[Us][BISHOP] & attacks_bb<BISHOP>(s, pos.pieces()))
            | (attackedBy[Us][ROOK  ] & attacks_bb<ROOK  >(s, pos.pieces()));
 
-        score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]);
+        score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]) * (1 + queenImbalance);
     }
 
     if (T)