Simplify away king infiltration.

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index be39f8a7b314019333a55cf27175fa2f3ac303a7..17597648bf36393fa2067ccbaf2ee071c33e51d2 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -145,7 +145,7 @@ namespace {
   constexpr Score ThreatByKing       = S( 24, 89);
   constexpr Score ThreatByPawnPush   = S( 48, 39);
   constexpr Score ThreatBySafePawn   = S(173, 94);
-  constexpr Score TrappedRook        = S( 52, 30);
+  constexpr Score TrappedRook        = S( 52, 10);
   constexpr Score WeakQueen          = S( 49, 15);
 
 #undef S
@@ -168,7 +168,7 @@ namespace {
     template<Color Us> Score passed() const;
     template<Color Us> Score space() const;
     ScaleFactor scale_factor(Value eg) const;
-    Score initiative(Score score, Score materialScore) const;
+    Score initiative(Score score) const;
 
     const Position& pos;
     Material::Entry* me;
@@ -524,7 +524,7 @@ namespace {
     b =   attackedBy[Them][ALL_PIECES]
        & ~stronglyProtected
        &  attackedBy[Us][ALL_PIECES];
-    score += RestrictedPiece * (popcount(b) + popcount(b & pos.pieces()));
+    score += RestrictedPiece * popcount(b);
 
     // Protected or unattacked squares
     safe = ~attackedBy[Them][ALL_PIECES] | attackedBy[Us][ALL_PIECES];
@@ -696,14 +696,11 @@ namespace {
   // known attacking/defending status of the players.
 
   template<Tracing T>
-  Score Evaluation<T>::initiative(Score score, Score materialScore) const {
+  Score Evaluation<T>::initiative(Score score) const {
 
     int outflanking =  distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
                      - distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
 
-    bool infiltration =   rank_of(pos.square<KING>(WHITE)) > RANK_4
-                       || rank_of(pos.square<KING>(BLACK)) < RANK_5;
-
     bool pawnsOnBothFlanks =   (pos.pieces(PAWN) & QueenSide)
                             && (pos.pieces(PAWN) & KingSide);
 
@@ -715,14 +712,12 @@ namespace {
     int complexity =   9 * pe->passed_count()
                     + 11 * pos.count<PAWN>()
                     +  9 * outflanking
-                    + 12 * infiltration
                     + 21 * pawnsOnBothFlanks
                     + 51 * !pos.non_pawn_material()
                     - 43 * almostUnwinnable
-                    - 100 ;
+                    - 95 ;
 
     // Give more importance to non-material score
-    score = (score * 2 - materialScore) / 2;
     Value mg = mg_value(score);
     Value eg = eg_value(score);
 
@@ -794,9 +789,6 @@ namespace {
     if (abs(v) > LazyThreshold + pos.non_pawn_material() / 64)
        return pos.side_to_move() == WHITE ? v : -v;
 
-    // Remember this score
-    Score materialScore = score;
-
     // Main evaluation begins here
 
     initialize<WHITE>();
@@ -815,7 +807,7 @@ namespace {
             + passed< WHITE>() - passed< BLACK>()
             + space<  WHITE>() - space<  BLACK>();
 
-    score += initiative(score, materialScore);
+    score += initiative(score);
 
     // Interpolate between a middlegame and a (scaled by 'sf') endgame score
     ScaleFactor sf = scale_factor(eg_value(score));