Decrease reduction for moves that escape a capture

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 29d71ea9e0cce28078ccf4a715521d85b3f6bbac..30b107ee9565c2254f93065cc5f76438f6f0a3e8 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"
@@ -89,23 +89,15 @@ namespace {
     std::string do_trace(const Position& pos);
   }
 
-  // Evaluation weights, initialized from UCI options
+  // Evaluation weights, indexed by evaluation term
   enum { Mobility, PawnStructure, PassedPawns, Space, KingDangerUs, KingDangerThem };
-  struct Weight { int mg, eg; } Weights[6];
+  const struct Weight { int mg, eg; } Weights[] = {
+    {289, 344}, {233, 201}, {221, 273}, {46, 0}, {271, 0}, {307, 0}
+  };
 
   typedef Value V;
   #define S(mg, eg) make_score(mg, eg)
 
-  // Internal evaluation weights. These are applied on top of the evaluation
-  // weights read from UCI parameters. The purpose is to be able to change
-  // the evaluation weights while keeping the default values of the UCI
-  // parameters at 100, which looks prettier.
-  //
-  // 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)
-  };
-
   // MobilityBonus[PieceType][attacked] contains bonuses for middle and end
   // game, indexed by piece type and number of attacked squares not occupied by
   // friendly pieces.
@@ -169,7 +161,6 @@ 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);
 
@@ -214,17 +205,6 @@ namespace {
   }
 
 
-  // weight_option() computes the value of an evaluation weight, by combining
-  // two UCI-configurable weights (midgame and endgame) with an internal weight.
-
-  Weight weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
-
-    Weight w = { Options[mgOpt] * mg_value(internalWeight) / 100,
-                 Options[egOpt] * eg_value(internalWeight) / 100 };
-    return w;
-  }
-
-
   // init_eval_info() initializes king bitboards for given color adding
   // pawn attacks. To be done at the beginning of the evaluation.
 
@@ -520,16 +500,9 @@ 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 +760,6 @@ 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;
@@ -912,13 +879,6 @@ namespace Eval {
 
   void init() {
 
-    Weights[Mobility]       = weight_option("Mobility (Midgame)", "Mobility (Endgame)", WeightsInternal[Mobility]);
-    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]);
-
     const double MaxSlope = 30;
     const double Peak = 1280;