Penalty for Knight when enemy pawns are few

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 71120fde8fb20ca99ff4e9d691ad7d31889258b7..1ff2dea7744c520daff7073c2bc315f0778648af 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -172,6 +172,7 @@ namespace {
   const Score RookOpenFile     = make_score(43, 21);
   const Score RookSemiopenFile = make_score(19, 10);
   const Score BishopPawns      = make_score( 8, 12);
+  const Score KnightPawns      = make_score( 8,  4);
   const Score MinorBehindPawn  = make_score(16,  0);
   const Score UndefendedMinor  = make_score(25, 10);
   const Score TrappedRook      = make_score(90,  0);
@@ -200,12 +201,12 @@ namespace {
   const int KingAttackWeights[] = { 0, 0, 2, 2, 3, 5 };
 
   // Bonuses for enemy's safe checks
-  const int QueenContactCheck = 12;
-  const int RookContactCheck  = 8;
-  const int QueenCheck        = 6;
-  const int RookCheck         = 4;
-  const int BishopCheck       = 1;
-  const int KnightCheck       = 2;
+  const int QueenContactCheck = 24;
+  const int RookContactCheck  = 16;
+  const int QueenCheck        = 12;
+  const int RookCheck         = 8;
+  const int BishopCheck       = 2;
+  const int KnightCheck       = 3;
 
   // KingExposed[Square] contains penalties based on the position of the
   // defending king, indexed by king's square (from white's point of view).
@@ -529,6 +530,10 @@ Value do_evaluate(const Position& pos, Value& margin) {
         if (Piece == BISHOP)
             score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
 
+        // Penalty for knight when there are few enemy pawns
+        if (Piece == KNIGHT)
+            score -= KnightPawns * std::max(5 - pos.count<PAWN>(Them), 0);
+
         if (Piece == BISHOP || Piece == KNIGHT)
         {
             // Bishop and knight outposts squares
@@ -878,9 +883,7 @@ Value do_evaluate(const Position& pos, Value& margin) {
                 ebonus -= ebonus / 4;
         }
 
-        // Increase the bonus if we have more non-pawn pieces
-        if (pos.count<ALL_PIECES>(  Us) - pos.count<PAWN>(  Us) >
-            pos.count<ALL_PIECES>(Them) - pos.count<PAWN>(Them))
+        if (pos.count<PAWN>(Us) < pos.count<PAWN>(Them))
             ebonus += ebonus / 4;
 
         score += make_score(mbonus, ebonus);