From: Arjun Temurnikar <arjuntemurnikano@gmail.com>
Date: Tue, 13 May 2014 19:35:10 +0000 (+0200)
Subject: Remove undefended minors
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=a3c8c4b70d6d21572a85d6175202db29e4f4bf2b

Remove undefended minors

Tested in "no regression" mode.

Passed both STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 68026 W: 12277 L: 12236 D: 43513

And LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 85682 W: 12861 L: 12836 D: 59985

bench: 7311935
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 341b5068..64b1bf4c 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -169,7 +169,6 @@ namespace {
   const Score RookSemiopenFile = make_score(19, 10);
   const Score BishopPawns      = make_score( 8, 12);
   const Score MinorBehindPawn  = make_score(16,  0);
-  const Score UndefendedMinor  = make_score(25, 10);
   const Score TrappedRook      = make_score(90,  0);
   const Score Unstoppable      = make_score( 0, 20);
 
@@ -520,16 +519,9 @@ namespace {
 
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 
-    Bitboard b, undefendedMinors, weakEnemies;
+    Bitboard b, weakEnemies;
     Score score = SCORE_ZERO;
 
-    // Undefended minors get penalized even if they are not under attack
-    undefendedMinors =  pos.pieces(Them, BISHOP, KNIGHT)
-                      & ~ei.attackedBy[Them][ALL_PIECES];
-
-    if (undefendedMinors)
-        score += UndefendedMinor;
-
     // Enemies not defended by a pawn and under our attack
     weakEnemies =  pos.pieces(Them)
                  & ~ei.attackedBy[Them][PAWN]