Symmetric king safety

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 29d71ea9e0cce28078ccf4a715521d85b3f6bbac..a945c5c7f2c29d34b18ac2ccd08ac3c6b97dcc9d 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -17,10 +17,10 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include <algorithm>
 #include <cassert>
 #include <iomanip>
 #include <sstream>
-#include <algorithm>
 
 #include "bitcount.h"
 #include "evaluate.h"
@@ -90,8 +90,8 @@ namespace {
   }
 
   // Evaluation weights, initialized from UCI options
-  enum { Mobility, PawnStructure, PassedPawns, Space, KingDangerUs, KingDangerThem };
-  struct Weight { int mg, eg; } Weights[6];
+  enum { Mobility, PawnStructure, PassedPawns, Space, KingSafety };
+  struct Weight { int mg, eg; } Weights[5];
 
   typedef Value V;
   #define S(mg, eg) make_score(mg, eg)
@@ -103,7 +103,7 @@ namespace {
   //
   // Values modified by Joona Kiiski
   const Score WeightsInternal[] = {
-    S(289, 344), S(233, 201), S(221, 273), S(46, 0), S(271, 0), S(307, 0)
+    S(289, 344), S(233, 201), S(221, 273), S(46, 0), S(289, 0)
   };
 
   // MobilityBonus[PieceType][attacked] contains bonuses for middle and end
@@ -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);
 
@@ -203,9 +202,9 @@ namespace {
   const int BishopCheck       = 2;
   const int KnightCheck       = 3;
 
-  // KingDanger[Color][attackUnits] contains the actual king danger weighted
-  // scores, indexed by color and by a calculated integer number.
-  Score KingDanger[COLOR_NB][128];
+  // KingDanger[attackUnits] contains the actual king danger weighted
+  // scores, indexed by a calculated integer number.
+  Score KingDanger[128];
 
 
   // apply_weight() weighs score 'v' by weight 'w' trying to prevent overflow
@@ -502,7 +501,7 @@ namespace {
 
         // Finally, extract the king danger score from the KingDanger[]
         // array and subtract the score from evaluation.
-        score -= KingDanger[Us == Search::RootColor][attackUnits];
+        score -= KingDanger[attackUnits];
     }
 
     if (Trace)
@@ -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]
@@ -787,12 +779,6 @@ namespace {
              sf = ScaleFactor(50 * sf / SCALE_FACTOR_NORMAL);
     }
 
-    // Stealmate detection
-    Color stm = pos.side_to_move();
-    if (   (ei.attackedBy[stm][ALL_PIECES] == ei.attackedBy[stm][KING])
-        && (!(ei.attackedBy[stm][KING] & ~ei.attackedBy[~stm][ALL_PIECES])))
-        sf = SCALE_FACTOR_DRAW;
-
     // Interpolate between a middlegame and a (scaled by 'sf') endgame score
     Value v =  mg_value(score) * int(ei.mi->game_phase())
              + eg_value(score) * int(PHASE_MIDGAME - ei.mi->game_phase()) * sf / SCALE_FACTOR_NORMAL;
@@ -916,8 +902,7 @@ namespace Eval {
     Weights[PawnStructure]  = weight_option("Pawn Structure (Midgame)", "Pawn Structure (Endgame)", WeightsInternal[PawnStructure]);
     Weights[PassedPawns]    = weight_option("Passed Pawns (Midgame)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
     Weights[Space]          = weight_option("Space", "Space", WeightsInternal[Space]);
-    Weights[KingDangerUs]   = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
-    Weights[KingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
+    Weights[KingSafety]     = weight_option("King Safety", "King Safety", WeightsInternal[KingSafety]);
 
     const double MaxSlope = 30;
     const double Peak = 1280;
@@ -925,9 +910,7 @@ namespace Eval {
     for (int t = 0, i = 1; i < 100; ++i)
     {
         t = int(std::min(Peak, std::min(0.4 * i * i, t + MaxSlope)));
-
-        KingDanger[1][i] = apply_weight(make_score(t, 0), Weights[KingDangerUs]);
-        KingDanger[0][i] = apply_weight(make_score(t, 0), Weights[KingDangerThem]);
+        KingDanger[i] = apply_weight(make_score(t, 0), Weights[KingSafety]);
     }
   }