Pins or discovered attacks on the opponent's queen

Bonus for pins or discovered attacks on the opponent's queen

STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 32020 W: 5914 L: 5652 D: 20454

LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 10946 W: 1530 L: 1375 D: 8041

Bench: 7031649

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 4a52e62658f0deccce3eea3c1287b9d87b3147fa..58058b1ba53b7b31d9923922526e03ec956f99ed 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -187,6 +187,7 @@ namespace {
   const Score OtherCheck          = S(10, 10);
   const Score ThreatByHangingPawn = S(71, 61);
   const Score LooseEnemies        = S( 0, 25);
   const Score OtherCheck          = S(10, 10);
   const Score ThreatByHangingPawn = S(71, 61);
   const Score LooseEnemies        = S( 0, 25);

+  const Score WeakQueen           = S(35,  0);

   const Score Hanging             = S(48, 27);
   const Score ThreatByPawnPush    = S(38, 22);
   const Score Unstoppable         = S( 0, 20);
   const Score Hanging             = S(48, 27);
   const Score ThreatByPawnPush    = S(38, 22);
   const Score Unstoppable         = S( 0, 20);


@@ -488,6 +489,13 @@ namespace {
         & ~(ei.attackedBy[Us][ALL_PIECES] | ei.attackedBy[Them][ALL_PIECES]))
         score += LooseEnemies;
 
         & ~(ei.attackedBy[Us][ALL_PIECES] | ei.attackedBy[Them][ALL_PIECES]))
         score += LooseEnemies;
 

+    // Bonus for pin or discovered attack on the opponent queen
+    if (   pos.count<QUEEN>(Them) == 1
+        && pos.slider_blockers(pos.pieces(),
+                               pos.pieces(Us, ROOK, BISHOP),
+                               pos.square<QUEEN>(Them)))
+        score += WeakQueen;
+

     // Non-pawn enemies attacked by a pawn
     weak = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Us][PAWN];
 
     // Non-pawn enemies attacked by a pawn
     weak = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Us][PAWN];