Dynamic complexity

Instead of computing the initiative bonus on the material score + dynamic score
compute it on (material score/2) + dynamic score,

Passed STC
http://tests.stockfishchess.org/tests/view/5e2c4945ab2d69d58394fa8f
LLR: 2.94 (-2.94,2.94) {-1.00,3.00}
Total: 39387 W: 7594 L: 7386 D: 24407
Ptnml(0-2): 658, 4519, 9165, 4649, 697

Passed LTC
http://tests.stockfishchess.org/tests/view/5e2c85ccab2d69d58394faa7
LLR: 2.95 (-2.94,2.94) {0.00,2.00}
Total: 32588 W: 4206 L: 3986 D: 24396
Ptnml(0-2): 244, 2909, 9738, 3111, 253

closes https://github.com/official-stockfish/Stockfish/pull/2516

Bench: 4765486

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index a1a3b4ed267c6293f135e9fdef1b2c5beea3a82d..be39f8a7b314019333a55cf27175fa2f3ac303a7 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -168,7 +168,7 @@ namespace {
     template<Color Us> Score passed() const;
     template<Color Us> Score space() const;
     ScaleFactor scale_factor(Value eg) const;
     template<Color Us> Score passed() const;
     template<Color Us> Score space() const;
     ScaleFactor scale_factor(Value eg) const;

-    Score initiative(Score score) const;
+    Score initiative(Score score, Score materialScore) const;

 
     const Position& pos;
     Material::Entry* me;
 
     const Position& pos;
     Material::Entry* me;


@@ -696,10 +696,7 @@ namespace {
   // known attacking/defending status of the players.
 
   template<Tracing T>
   // known attacking/defending status of the players.
 
   template<Tracing T>

-  Score Evaluation<T>::initiative(Score score) const {
-
-    Value mg = mg_value(score);
-    Value eg = eg_value(score);
+  Score Evaluation<T>::initiative(Score score, Score materialScore) const {

 
     int outflanking =  distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
                      - distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
 
     int outflanking =  distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
                      - distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));


@@ -724,6 +721,11 @@ namespace {
                     - 43 * almostUnwinnable
                     - 100 ;
 
                     - 43 * almostUnwinnable
                     - 100 ;
 

+    // Give more importance to non-material score
+    score = (score * 2 - materialScore) / 2;
+    Value mg = mg_value(score);
+    Value eg = eg_value(score);
+

     // Now apply the bonus: note that we find the attacking side by extracting the
     // sign of the midgame or endgame values, and that we carefully cap the bonus
     // so that the midgame and endgame scores do not change sign after the bonus.
     // Now apply the bonus: note that we find the attacking side by extracting the
     // sign of the midgame or endgame values, and that we carefully cap the bonus
     // so that the midgame and endgame scores do not change sign after the bonus.


@@ -792,6 +794,9 @@ namespace {
     if (abs(v) > LazyThreshold + pos.non_pawn_material() / 64)
        return pos.side_to_move() == WHITE ? v : -v;
 
     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>();
     // Main evaluation begins here
 
     initialize<WHITE>();


@@ -810,7 +815,7 @@ namespace {
             + passed< WHITE>() - passed< BLACK>()
             + space<  WHITE>() - space<  BLACK>();
 
             + passed< WHITE>() - passed< BLACK>()
             + space<  WHITE>() - space<  BLACK>();
 

-    score += initiative(score);
+    score += initiative(score, materialScore);

 
     // Interpolate between a middlegame and a (scaled by 'sf') endgame score
     ScaleFactor sf = scale_factor(eg_value(score));
 
     // Interpolate between a middlegame and a (scaled by 'sf') endgame score
     ScaleFactor sf = scale_factor(eg_value(score));