Remove SafeCheck (#946)

lucasart · mcostalba · commit ab4f498bbcf6 · 2016-12-31T13:52:42.000+01:00
It was a bit of a hack, without intrinsic value, but rather compensating for the
fact that checks were mistuned.

STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 88308 W: 15553 L: 15545 D: 57210

LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 53115 W: 6741 L: 6662 D: 39712

bench 5468995
diff --git a/src/evaluate.cpp b/src/evaluate.cpp
@@ -190,7 +190,6 @@ namespace {
   const Score RookOnPawn          = S( 8, 24);
   const Score TrappedRook         = S(92,  0);
   const Score CloseEnemies        = S( 7,  0);
-  const Score SafeCheck           = S(20, 20);
   const Score OtherCheck          = S(10, 10);
   const Score ThreatByHangingPawn = S(71, 61);
   const Score LooseEnemies        = S( 0, 25);
@@ -214,10 +213,10 @@ namespace {
 
   // Penalties for enemy's safe checks
   const int QueenContactCheck = 997;
-  const int QueenCheck        = 695;
-  const int RookCheck         = 638;
-  const int BishopCheck       = 538;
-  const int KnightCheck       = 874;
+  const int QueenCheck        = 745;
+  const int RookCheck         = 688;
+  const int BishopCheck       = 588;
+  const int KnightCheck       = 924;
 
 
   // eval_init() initializes king and attack bitboards for a given color
@@ -447,7 +446,7 @@ namespace {
 
         // Enemy queen safe checks
         if ((b1 | b2) & ei.attackedBy[Them][QUEEN] & safe)
-            kingDanger += QueenCheck, score -= SafeCheck;
+            kingDanger += QueenCheck;
 
         // For other pieces, also consider the square safe if attacked twice,
         // and only defended by a queen.
@@ -457,22 +456,22 @@ namespace {
 
         // Enemy rooks safe and other checks
         if (b1 & ei.attackedBy[Them][ROOK] & safe)
-            kingDanger += RookCheck, score -= SafeCheck;
+            kingDanger += RookCheck;
 
         else if (b1 & ei.attackedBy[Them][ROOK] & other)
             score -= OtherCheck;
 
         // Enemy bishops safe and other checks
         if (b2 & ei.attackedBy[Them][BISHOP] & safe)
-            kingDanger += BishopCheck, score -= SafeCheck;
+            kingDanger += BishopCheck;
 
         else if (b2 & ei.attackedBy[Them][BISHOP] & other)
             score -= OtherCheck;
 
         // Enemy knights safe and other checks
         b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT];
         if (b & safe)
-            kingDanger += KnightCheck, score -= SafeCheck;
+            kingDanger += KnightCheck;
 
         else if (b & other)
             score -= OtherCheck;
