From: Joerg Oster <osterj165@googlemail.com>
Date: Thu, 3 Apr 2014 08:38:11 +0000 (+0200)
Subject: Queen vs. 3 pieces imbalance
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=299afcd88653739b80691991f7e5072a0505f542;hp=c15b132f033881b7bc0e8c76698d928798dff921

Queen vs. 3 pieces imbalance

Passed both STC
LLR: 7.32 (-2.94,2.94) [-1.50,4.50]
Total: 98108 W: 18087 L: 17576 D: 62445

And LTC
LLR: 2.95 (-2.94,2.94) [0.00,6.00]
Total: 15082 W: 2417 L: 2248 D: 10417

bench: 7717336
---

diff --git a/src/material.cpp b/src/material.cpp
index 0fe132d4..9e46d05d 100644
--- a/src/material.cpp
+++ b/src/material.cpp
@@ -115,6 +115,17 @@ namespace {
 
         value += pc * v;
     }
+
+    // Queen vs. 3 minors slightly favours the minors
+    if (pieceCount[Us][QUEEN] == 1 && pieceCount[Them][QUEEN] == 0)
+    {
+        int n = pieceCount[Them][KNIGHT] - pieceCount[Us][KNIGHT];
+        int b = pieceCount[Them][BISHOP] - pieceCount[Us][BISHOP];
+
+        if ((n == 2 && b == 1) || (n == 1 && b == 2))
+            value -= 66 * 16;
+    }
+
     return value;
   }