X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fevaluate.cpp;h=58058b1ba53b7b31d9923922526e03ec956f99ed;hp=4a52e62658f0deccce3eea3c1287b9d87b3147fa;hb=07b247f9434f3633570aa124539ed5d2fc4f904f;hpb=abac509ccb1f197da1159ce02daaf4fa737c32e5;ds=sidebyside

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 4a52e626..58058b1b 100644
--- 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 WeakQueen           = S(35,  0);
   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;
 
+    // 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];