From: Stéphane Nicolet <cassio@free.fr>
Date: Sat, 21 May 2016 08:05:19 +0000 (+0200)
Subject: Pins or discovered attacks on the opponent's queen
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=07b247f9434f3633570aa124539ed5d2fc4f904f;ds=sidebyside

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 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];